Dissertations / Theses: 'Insect pests – Biological control'

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Malek, Robert Nehme. "Novel Monitoring and Biological Control of Invasive Insect Pests." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/257781.

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Invasive species are alien to the ecosystem under consideration and cause economic or environmental damage or harm to human health. Two alien insects that fit this description are the brown marmorated stink bug, Halyomorpha halys and the spotted lanternfly, Lycorma delicatula. Both invaders are polyphagous pests that feed on a myriad of plant species and inflict severe crop losses. As sustainable control methods depend on the accurate monitoring of species’ invasion and involve the use of natural enemies, we addressed these two facets by exploring novel monitoring techniques and deciphering host-parasitoid interactions for improved integrated pest management. Thus, we adopted ‘BugMap’, a citizen science initiative that enables students, farmers and everyday citizens to report sightings of H. halys from Italy, with emphasis on Trentino-Alto Adige. Aside from fostering citizen participation in scientific endeavors and the enhanced literacy that ensues, BugMap helped uncover the invasion dynamics of H. halys and forecast its potential distribution in Trentino, all while coordinating technical monitoring and informing management strategies. The most promising agent currently under study for the classical biological control of H. halys is the Asian egg parasitoid Trissolcus japonicus. To assess the wasp’s potential non-target impacts, we investigated its foraging behavior in response to chemical traces ‘footprints’ deposited by its main host H. halys and by a suboptimal predatory species, the spined soldier bug, Podisus maculiventris. Wasps exhibited a ‘motivated searching’ when in contact with footprints originating from both species. However, T. japonicus arrestment was significantly stronger in response to H. halys footprints, compared with P. maculiventris, implying the presence of underlying chemical cues that shape its natural preferences. A series of GC-MS chemical analyses revealed that n-tridecane and (E)-2-decenal were more abundant in H. halys footprints and are probably the key components utilized by the wasp for short range host location. The function of the aforementioned compounds was studied, n-tridecane acted as an arrestant, prolonging T. japonicus residence time, whereas (E)-2-decenal fulfilled its presumed defensive role and repelled the wasp. These results shed new light on the chemical ecology of T. japonicus and help expand the understanding of parasitoid foraging and its implications for classical biological control. Moving to the other invader L. delicatula, an egg parasitoid Anastatus orientalis was reported attacking it at high rates in its native range in Eastern Asia and may play a key role in reducing its populations there. A series of bioassays revealed that wasps responded to footprints deposited by L. delicatula gravid females by initiating a strong searching behavior. Moreover, A. orientalis preferred to oviposit in egg masses with intact oothecae, suggesting that the host’s egg covering functions as a trigger for A. orientalis probing and oviposition. Thus, A. orientalis not only overcomes, but also reverses an important line of host structural defense for its own fitness gains. This dissertation discusses the benefits of combining citizen science with traditional monitoring, and the usefulness of decoding host-parasitoid interactions to design more efficacious management strategies of invasive insect pests.

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Malek, Robert Nehme. "Novel Monitoring and Biological Control of Invasive Insect Pests." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/257781.

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Abstract:

Invasive species are alien to the ecosystem under consideration and cause economic or environmental damage or harm to human health. Two alien insects that fit this description are the brown marmorated stink bug, Halyomorpha halys and the spotted lanternfly, Lycorma delicatula. Both invaders are polyphagous pests that feed on a myriad of plant species and inflict severe crop losses. As sustainable control methods depend on the accurate monitoring of species’ invasion and involve the use of natural enemies, we addressed these two facets by exploring novel monitoring techniques and deciphering host-parasitoid interactions for improved integrated pest management. Thus, we adopted ‘BugMap’, a citizen science initiative that enables students, farmers and everyday citizens to report sightings of H. halys from Italy, with emphasis on Trentino-Alto Adige. Aside from fostering citizen participation in scientific endeavors and the enhanced literacy that ensues, BugMap helped uncover the invasion dynamics of H. halys and forecast its potential distribution in Trentino, all while coordinating technical monitoring and informing management strategies. The most promising agent currently under study for the classical biological control of H. halys is the Asian egg parasitoid Trissolcus japonicus. To assess the wasp’s potential non-target impacts, we investigated its foraging behavior in response to chemical traces ‘footprints’ deposited by its main host H. halys and by a suboptimal predatory species, the spined soldier bug, Podisus maculiventris. Wasps exhibited a ‘motivated searching’ when in contact with footprints originating from both species. However, T. japonicus arrestment was significantly stronger in response to H. halys footprints, compared with P. maculiventris, implying the presence of underlying chemical cues that shape its natural preferences. A series of GC-MS chemical analyses revealed that n-tridecane and (E)-2-decenal were more abundant in H. halys footprints and are probably the key components utilized by the wasp for short range host location. The function of the aforementioned compounds was studied, n-tridecane acted as an arrestant, prolonging T. japonicus residence time, whereas (E)-2-decenal fulfilled its presumed defensive role and repelled the wasp. These results shed new light on the chemical ecology of T. japonicus and help expand the understanding of parasitoid foraging and its implications for classical biological control. Moving to the other invader L. delicatula, an egg parasitoid Anastatus orientalis was reported attacking it at high rates in its native range in Eastern Asia and may play a key role in reducing its populations there. A series of bioassays revealed that wasps responded to footprints deposited by L. delicatula gravid females by initiating a strong searching behavior. Moreover, A. orientalis preferred to oviposit in egg masses with intact oothecae, suggesting that the host’s egg covering functions as a trigger for A. orientalis probing and oviposition. Thus, A. orientalis not only overcomes, but also reverses an important line of host structural defense for its own fitness gains. This dissertation discusses the benefits of combining citizen science with traditional monitoring, and the usefulness of decoding host-parasitoid interactions to design more efficacious management strategies of invasive insect pests.

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Williams, Elizabeth Catherine. "Entomopathogenic nematodes as control agents of statutory insect pests." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265978.

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Chang, Gary C. "Ecological interaction among natural enemies and its consequences for biological control /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5205.

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Ramos, Olgaly. "Entomopathogenic nematodes for the biological control of stored product insect pests /." Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.

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Mazahery-Laghab, Hojjatollah. "Endogenous resistance to insect pests in alfalfa : engineering for enhanced resistance." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4695/.

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Alfalfa (Medicago sativa) is a valuable forage crop grown throughout the World. While the crop is resistant to attack by many insect pests, it is subject to potentially severe losses through the action of several specific pests, which are adapted to alfalfa as a host. The most economically damaging of these pests is the alfalfa weevil, Hypera postica. This thesis investigates the endogenous defences of alfalfa against insects, which are responsible for its resistance to non-pest species, and develops a strategy for increasing the resistance of alfalfa towards pest species, specifically alfalfa weevil. The role of saponins in the resistance of alfalfa towards non-pest species has been investigated by using successive insect bioassays, carried out with extracts, mixtures of compounds, and purified compounds, to identify which compounds present in alfalfa tissues are responsible for toxicity towards insects. Crude saponin extracts, in 80% methanol, from alfalfa seedling tissues were bioassayed against the cowpea seed weevil, Callosobruchus maculatus. Both extracts from shoot and root tissues caused larval mortality and delayed development when incorporated into an artificial diet at levels comparable to those found in alfalfa, but lower levels of root saponin extracts showed probiotic effects, whereas lower levels of shoot saponins were still toxic. Hydrolysis of the saponins present in these extracts decreased their toxicity. Purified saponin mixtures were prepared by butanol partition and ether precipitation, and were bioassayed against potato aphid (Aulacorthum solani) in a liquid artificial diet, which allowed quantitative effects to be accurately assayed. Shoot saponins showed a concentration-dependent toxic effect, decreasing survival over an initial 5 day period, decreasing growth, and inhibiting fecundity (measured by nymph production) in these insects. Alfalfa root saponins showed no deleterious effects below a threshold level, but caused complete mortality above this level. The alfalfa saponin mixtures were separated into fractions by chromatography on a reverse phase column. Bioassays showed that the toxicity towards potato was associated only with fractions containing saponins, and that fractions containing a component identified as soyasaponin I were more toxic to the aphids than others. Finally, two saponins purified from alfalfa, soyasaponin I and medicoside A, were assayed. These assays showed that soyasaponin was consistently more toxic in effects on mortality, growth and fecundity. It was concluded that alfalfa saponins, and in particular soyasaponin I, were major factors in the resistance of alfalfa towards potato aphid, and other insects. A saponin mixture from another species, sugar beet {Beta vulgaris) was also toxic to aphids, supporting the view that saponins have a general role in resistance to insects. Inhibition of insect digestive proteolysis by expression of a foreign protein protease inhibitor was selected as a strategy to protect transgenic alfalfa against alfalfa weevil. The major protease activity in larvae of this msect was shown to be due to cysteine proteases, which could be inhibited by cystatins. Rice cystatin was produced in large quantity using a recombinant protein expression system in E. coli for use in a "proving" experiment. Incorporation of the rice cystatin into an alfalfa weevil larvae artificial diet decreased survival, showing that this approach was feasible.

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Zhou, Yanmin. "Insect adhesion on rough surfaces and properties of insect repellent surfaces." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709055.

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Greenfield, Bethany Patricia Jane. "Metarhizium pathogenesis of mosquito larvae." Thesis, Swansea University, 2014. https://cronfa.swan.ac.uk/Record/cronfa42819.

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Smith, Ethan A. "Is everything connected? following the predators, pests, and plants within a no-till, western Montana agroecosystem /." CONNECT TO THIS TITLE ONLINE, 2006. http://etd.lib.umt.edu/theses/available/etd-12212006-142245/.

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Adedipe, Folukemi Ebunoluwa. "Investigation of ecological behavior of two Coccinellidae beetle adults for biological control." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10491.

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Thesis (M.S.)--West Virginia University, 2009.
Title from document title page. Document formatted into pages; contains vii, 60 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

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Helvering, Leah M. "Cloning of genes encoding larvicidal proteins from Bacillus thuringiensis subsp. israelensis into the cyanobacterial hybrid vector, pTNTV." Virtual Press, 1989. http://liblink.bsu.edu/uhtbin/catkey/562782.

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Bacillus thuringiensis subsp. isrealensis (B.t.i.) produces a crystalline endotoxin specific for some larvae of mosquitoes that are vectors of the malaria parasite and other infectious diseases. Fragments were obtained from the 108 kb plasmid from B.t.i. strain 4Q2 which encodes several proteins comprising the delta-endotoxin. These DNA fragments were inserted into the hybrid cyanobacterial cloning vector, pTNTV, downstream from its powerful lambda promoter, and the chimaeras were transformed into Escherichia coli. Ampicillin resistant transformants were screened with radioactively labelled oligonucleotides whose sequences were determined from the published sequences of the B.t.i. 130 kDa polypeptide. Clones showing hybridization were used in bioassays to determine their level of toxicity to the fourth instar larvae of the Aedes aegypti mosquito. Twelve clones were found that demonstrated toxicity which was statistically significantly greater than that observed in controls. Plasmid DNA from some of these clones was isolated, cut with restriction endonucleases, and viewed through agarose gel electrophoresis to confirm that B.t.i. fragments had been inserted into the vector. Future work will investigate the expression of these cloned toxin genes in transformable cyanobacteria and will determine their subsequent activity against the fourth instar larvae of Aedes aegypti and Anopheles quadrimaculatus.
Department of Biology

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Er, Mehmet Kubilay. "Studies on the microbial control of pastureland leatherjackets (Tipula spp. Tipulidae: Diptera)." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327215.

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Jenkins, Paul E. "Control of the grape berry moth, Paralobesia viteana, using reduced-risk insecticides, cultural controls, and conservation of natural enemies." Diss., Connect to online resource - MSU authorized users, 2006.

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Haas, Jucelaine. "Toxicidade de extratos vegetais ao percevejo bronzeado do eucalipto Thaumastocoris peregrinus (hemiptera: heteroptera: thaumastocoridae) e organismos não-alvo." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1628.

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CAPES; CNPq
Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae) é um inseto originário da Austrália que está causando sérios danos à cultura do eucalipto ao redor do mundo. Ao alimentar-se da seiva das folhas, causa seu bronzeamento, podendo levar à desfolha. Medidas de controle estão sendo estudadas e a mais promissora é o parasitoide de ovos Cleruchoides noackae (Hymenoptera: Mymaridae). Produtos alternativos a base de compostos provenientes de plantas com potencial inseticida também poderiam ser uma ferramenta importante, e talvez serem utilizados concomitantemente com o parasitoide, visando um controle mais efetivo. Desta forma, o objetivo deste trabalho foi verificar a ação dos extratos aquosos de Matricaria chamomilla, Echinodorus grandiflorus, Punica granatum, Maytenus ilicifolia e Origanum majorana a 5% sobre T. peregrinus. Além disso, estudar sua possível toxicidade contra C. noackae e Gallus domesticus L., tendo em vista que estes compostos podem ter efeito negativo indesejado sobre organismos não alvo. Em uma primeira etapa, cromatografia líquida de alta eficiência (HPLC) foi utilizada para verificar os compostos fenólicos presentes nos extratos. Os extratos, então, foram testados sobre percevejo adultos, em confinamento (para verificar a ação inseticida) e teste de livre escolha (para verificar a ação repelente). Os três extratos que mostraram melhores resultados foram selecionados para os testes com os organismos não alvo. Com relação à C. noackae, testes pré e pós-parasitismo, de confinamento e de livre-escolha foram realizados para verificar se os extratos afetariam a escolha do hospedeiro pelas fêmeas ou o desenvolvimento das fases imaturas do parasitoide. Para verificar se os extratos seriam tóxicos a G. domesticus, estes foram adicionados à dieta de aves juvenis por cinco dias. Parâmetros como peso, consumo de alimento, quantificação de enzimas séricas e análise histopatológica foram realizados. Por meio das análises cromatográficas, foram detectados os ácidos gálico, ferúlico, cafeico, cumárico e vanílico. Os extratos levaram à mortalidade de 100% dos insetos em até 49% do tempo, quando comparados com a testemunha, mas E. grandiflorus, Matricaria chamomilla e Maytenus ilicifolia destacaram-se mostrando efeito repelente, sendo selecionados para a próxima etapa. Nenhum destes afetou a escolha do hospedeiro pela fêmea ou a emergência dos parasitoides, quando comparado com a testemunha. Além disso, os extratos não causaram alterações em G. domesticus, em nenhum dos parâmetros avaliados. Desta forma, verificou-se que E. grandiflorus, Matricaria chamomilla e Maytenus ilicifolia têm potencial para serem utilizados no controle de T. peregrinus, bem como mostraram-se seguros para C. noackae e G. domesticus.
Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae ) is an insect from Australia which is causing severe damage to eucalyptus crops around the world. When feeding from the leaves sap, it causes bronzening, and in extreme cases, may lead to the tree death. Control methods have been studied and the most promising so far is the egg parasitoid Cleruchoides noackae (Hymenoptera: Mymaridae). Alternative products from plants with insecticidal properties could also be a viable option, and they might even be used concomitantly with C. noackae, aiming for a most effective control, but still safe for the environment. Thus, the objective of this work was to verify the action of 5% aqueous plant extracts of Matricaria chamomilla, Echinodorus grandiflorus, Punica granatum, Maytenus ilicifolia a n d Origanum majorana on T. peregrinus. In addition, we aimed to study the extracts potential toxicity to C. noackae and Gallus domesticus L., since the plant compounds might have negative effect upon the non-target organisms. At first, HPLC (High Performance Liquid Chromatography) was used to verify which phenolic compounds would be found in the plant extracts. These were tested on bronze bug adults, in confinement test (to verify the insecticidal action of the extracts) and free-choice test (to verify the repellency). The extracts that showed better results were selected for further tests with non-target organisms. Regarding C. noackae, pre-parasitism and post-parasitism, confinement and free-choice tests were performed to verify if the extracts would affect the host-choosing by the female or the development of the immature stages of the parasitoid. To verify if the extracts would be toxic to G. domesticus, the plant extracts were added to young birds feed for five days. Parameters such as weight gain, food intake, quantification of serum enzymes and histopathological analysis were carried out. HPLC analysis detected gallic, ferulic, vanillic, caffeic and cumaric acid in the extracts samples. All plant extracts tested reduced T. peregrinus survival, but E. grandiflorus, Matricaria chamomilla Maytenus ilicifolia had also a repellent effect, and were tested on the non-target organisms. None of these extracts affected neither the host choice by C. noackae nor adult emergency, when compared to the control group. In addition, the extracts did not cause alterations in any of the studied parameters. Thus, we verified that E. grandiflorus, Matricaria chamomilla and Maytenus ilicifolia have potential to be used to control T. peregrinus and are safe to C. noackae and G. domesticus.

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Tremblay, Annie C. "The role of birds as predators and potential biocontrol agents of insect pests in corn fields." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ50898.pdf.

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Goble, Tarryn Anne. "Investigation of entomopathogenic fungi for control of false codling moth, Thaumatotibia leucotrata, Mediterranean fruit fly, Ceratitis capitata and Natal fruit fly, C. rosa in South African citrus." Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1005409.

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The biology of key citrus pests Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae), Ceratitis capitata Wiedemann (Diptera: Tephritidae) and Ceratitis rosa Karsch (Diptera: Tephritidae) includes their dropping from host plants to pupate in the soil below citrus trees. Since most EP fungi are soil-borne microorganisms, the development and formulation of alternative control strategies using these fungi as subterranean control agents, targeted at larvae and pupae in the soil, can potentially benefit existing IPM management of citrus in South Africa. Thus, a survey of occurrence of entomopathogenic fungi was undertaken on soils from citrus orchards and natural vegetation (refugia) on conventionally and organically managed farms in the Eastern Cape Province in South Africa. A method for baiting soil samples with citrus pest T. leucotreta and C. capitata larvae, as well as with the standard bait insect, Galleria mellonella Linnaeus (Lepidoptera: Pyralidae), was implemented. Sixty-two potentially useful entomopathogenic fungal isolates belonging to four genera were collected from 288 soil samples, an occurrence frequency of 21.53%. The most frequently isolated entomopathogenic fungal species was Beauveria bassiana (Balsamo) Vuillemin (15.63%), followed by Metarhizium anisopliae var. anisopliae (Metschnikoff) Sorokin (3.82%). Galleria mellonella was the most effective insect used to isolate fungal species (χ2=40.13, df=2, P≤ 0.005), with a total of 45 isolates obtained, followed by C. capitata with 11 isolates, and T. leucotreta with six isolates recovered. There was a significantly (χ2=11.65, df=1, P≤ 0.005) higher occurrence of entomopathogenic fungi in soil samples taken from refugia compared to cultivated orchards of both organically and conventionally managed farms. No significant differences were observed in the recovery of fungal isolates when soil samples from both farming systems were compared. The physiological effects and host range of 21 indigenous fungal isolates obtained in the Eastern Cape were investigated in the laboratory to establish whether these isolates could be effectively used as biological control agents against the subterranean life stages of C. rosa, C. capitata and T. leucotreta. When these pests were treated with a fungal concentration of 1 x 10⁷ conidia ml⁻¹, the percentage of T. leucotreta adults which emerged in fungal treated sand ranged from 5 to 60% (F=33.295; df=21; P=0.0001) depending on fungal isolate and the percentage of pupae with visible signs of mycosis ranged from 21 to 93% (F= 96.436; df=21; P=0.0001). Based on fungal isolates, the percentage adult survival in C. rosa and C. capitata ranged from 30 to 90% and 55 to 86% respectively. The percentage of C. rosa and C. capitata puparia with visible signs of mycosis ranged from 1 to 14% and 1 to 11% respectively. Deferred mortality due to mycosis in C. rosa and C. capitata adult flies ranged from 1 to 58% and 1 to 33% respectively, depending on fungal isolate. Entomopathogenic fungal isolates had a significantly greater effect on the adults of C. rosa and C. capitata than they did on the puparia of these two fruit fly species. Further, C. rosa and C. capitata did not differ significantly in their response to entomopathogenic fungi when adult survival or adult and pupal mycosis were considered. The relative potency of the four most virulent Beauveria isolates as well as the commercially available Beauveria bassiana product, Bb Plus® (Biological Control Products, South Africa), were compared against one another as log-probit regressions of mortality against C. rosa, C. capitata and T. leucotreta which all exhibited a dose-dependent response. Against fruit flies the estimated LC50 values of all five Beauveria isolates ranged from 5.5 x 10¹¹ to 2.8 x 10¹² conidia/ml⁻¹. There were no significant differences between the relative potencies of these five fungal isolates. When T. leucotreta was considered, isolates: G Moss R10 and G 14 2 B5 and Bb Plus® were significantly more pathogenic than G B Ar 23 B3 and FCM 10 13 L1. The estimated LC₅₀ values of the three most pathogenic isolates ranged from 6.8 x 10⁵ to 2.1 x 10⁶ conidia/ml⁻¹, while those of the least pathogenic ranged from 1.6 x 10⁷ to 3.7 x 10⁷ conidia/ml⁻¹. Thaumatotibia leucotreta final instar larvae were exposed to two conidial concentrations, at four different exposure times (12, 48, 72 and 96 hrs) and showed an exposure time-dependant relationship (F=5.43; df=3; P=0.001). At 1 x 10⁷conidia/ml⁻¹ two Beauveria isolates: G Moss R10 and G 14 2 B5 were able to elicit a response in 50% of test insects at 72 hrs (3 days) exposure. Although a limited amount of mycosis was observed in the puparia of both fruit fly species, deferred adult mortality due to mycosis was high. The increased incidence of adult mortality suggests that post emergence mycosis in adult fruit flies may play a more significant role in field suppression than the control of fruit flies at the pupal stage. The increased incidence of pupal mortality, as well as the relatively low concentrations of conidia required to elicit meaningful responses in T. leucotreta pupae may suggest that pre-emergent control of false codling moth will play a more significant role in field suppression than the control of adult life stages using indigenous isolates of entomopathogenic fungi. Various entomopathogenic fungal application techniques targeted at key insect pests within integrated pest management (IPM) systems of citrus are discussed.

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Costa, Suzana Regina Silveira [UNESP]. "Caracterização molecular de populações do inseto praga psilídeo de concha (Glycaspis brimblecombei) por meio de marcadores do tipo ITS 1 (Internal Tanscribed Spacer 1)." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/92450.

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Made available in DSpace on 2014-06-11T19:26:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-09-28Bitstream added on 2014-06-13T20:14:32Z : No. of bitstreams: 1 costa_srs_me_botib.pdf: 721918 bytes, checksum: 02872d35ed926393735b601733a62996 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O gênero Eucalyptus é originário da Austrália e está estabelecido no Brasil há mais de um século. Atualmente, o Brasil tem a segunda maior área plantada, formando monoculturas, que favorecem o estabelecimento de insetos praga. No ano de 2003 foi verificada pela primeira vez no país a ocorrência de Glycaspis brimblecombei, espécie descrita por Moore (Hemiptera, Psyllidae). Tal espécie também é conhecida por psilídeo de concha, em plantios de Eucalyptus sp. no estado de São Paulo. Devido sua alta capacidade adaptativa, atualmente se encontra amplamente distribuído por todo território nacional. Os danos causados por sua infestação são inúmeros, resultando em perdas consideráveis para o setor florestal e consequentemente para a economia brasileira. As populações do psilídeo de concha apresentam baixa variação morfológica, dificultando sua identificação; assim, análises moleculares, tais quais o uso de marcadores, podem auxiliar a responder essas questões. Um marcador amplamente utilizado, por sua alta variabilidade, é o espaçador interno transcrito do DNA ribossomal (ITS). Deste modo, o marcador ITS foi utilizado neste trabalho para averiguar a dinâmica populacional do psilídeo de concha de quatro regiões do estado de São Paulo. A sequência do ITS1 apresentou um intervalo de 291 pb em 88,73% das amostras. Os sítios polimórficos foram identificados no intervalo de 80 a 200 pb, sendo que na população de Pedra Bela foi observada a maior distribuição destes. Além disso, observou-se a ocorrência de seis haplótipos distribuídos nas quatro populações. O haplótipo 1 esteve presente em todas as populações, enquanto que o haplótipo 6 foi somente identificado na população de Criação de Laboratório. A diversidade nucleotídica (Pi) das populações foi de 0,00445, sendo que a de Criação de Laboratório...
Eucalyptus genus is derived from Australia and is settled in Brazil for more than a century now. Currently, Brazil has the second largest planted area, forming monocultures that smooth infestation with pest-insects. In 2003, the occurrence of Glycaspis brimblecombei, species described by Moore (Hemiptera, Psyllidae), was detected in Brazil for the first time. The said species is also known as red gum lerp, in Eucalyptus sp plantations in the State of São Paulo. Because of their high capacity of adaptation, nowadays they are found widely distributed all over the domestic territory. Damages caused by their infestation are numerous, resulting in considerable losses for the forestry sector and, consequently, for the Brazilian economy. Red gum lerp populations present a low rate of morphological variation, which makes their identifiction more difficult. Accordingly, molecular tests, such as the use of markers, may help answering such questions. A widely used marker, due to its high variability, is the internal transcribed spacer of ribosomal DNA (ITS). Thus, the ITS marker was used in this paper to investigate the population dynamics of red gum lerps from four regions in the State of São Paulo. ITS1 sequence showed a range of 291 bp in 88.73% of the samples. Polymorphic sites were identified in the range of 80-200 bp, with the population from Pedra Bela showing the highest distribution. Moreover, the occurrence of six haplotypes distributed in the four populations was found. Haplotype 1 was present in all populations, while haplotype 6 was identified in lab-developed population only. The nucleotide diversity (Pi) of populations was 0.00445, while the lab-developed population showed the highest Pi value as between the four populations. In Botucatu, no diversity was found. Specific oligonucleotides flanking the polymorphic regions of the... (Complete abstract click electronic access below)

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Scudeler, Elton Luiz [UNESP]. "Efeito do óleo de nim (Azadirachta indica A. Juss) no intestino médio de Ceraeochrysa claveri (Navás, 1911) (Neuroptera: Chrysopidae): estudo citoquímico, imunocitoquímico e ultraestrutural." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/99436.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Ceraeochrysa claveri, popularmente conhecido como bicho lixeiro, é um inseto predador de ovos e larvas de insetos pragas encontrados em diferentes ecossistemas agrícolas. O bicho lixeiro se destaca por apresentar potencial para ser utilizado em programas de Controle Biológico, uma vez que é predador na fase de larva, apresenta curto tempo de desenvolvimento, fácil criação massal e alto potencial reprodutivo na fase adulta. Com o propósito de aprofundar o conhecimento na morfologia e ultraestrutura do intestino médio de C. claveri, o objetivo deste trabalho foi caracterizar histológica e ultraestruturalmente o intestino médio de C. claveri no terceiro ínstar de larva, pupa e adulto. Objetivamos, ainda, avaliar o efeito da ingestão do óleo de nim (Azadirachta indica A. Juss) (Meliaceae) sobre as células epiteliais do intestino médio de larva de terceiro ínstar, pupa e adulto de C. claveri. Ovos de Diatraea saccharalis foram tratados com óleo de nim em três diferentes concentrações (0,5; 1 e 2%) e oferecidos como alimento a larvas de C. claveri durante todo período larval. Após coleta e fixação do intestino médio de larva, pupa e adulto (grupos controle e tratados com óleo de nim), as regiões do mesêntero (anterior, média e posterior) foram processadas para análise histológica (citoquímica e imunocitoquímica) e para análise ultraestrutural. Nossos resultados mostraram que o intestino médio de C. claveri, para as três fases do ciclo de vida, é do tipo pseudoestratificado, composto por células colunares, regenerativas e endócrinas; diferenças morfológicas e ultraestruturais no epitélio permitem caracterizar duas regiões, anterior e posterior, atuando respectivamente na secreção e absorção; região média apresenta características...
Ceraeochrysa claveri, popularly known as trash-carriers is a predator insect of eggs and larvae of insect pests found in different agroecosystems. The trash-carriers stands out because it has the potential to be used in biological control programs, once it is a predator in the larval stage; it has short developmental times, easy mass-rearing and high reproductive potential in adult stage. In order to deepen the knowledge on the morphology and ultrastructure of the midgut of C. claveri, the aim of this study was to characterize histological and ultrastructurally the midgut of C. claveri in the third instar larva, pupa and adult. We also evaluate the effect of ingestion of neem oil (Azadirachta indica A. Juss) (Meliaceae) on the midgut epithelial cells of third instar larva, pupa and adult of C. claveri. Diatraea saccharalis eggs were treated with neem oil at three different concentrations (0.5, 1 and 2%) and provided as food to larvae of C. claveri throughout the larval period. After collected and fixed the midgut of larva, pupa and adult (control and treated groups with neem oil), the midgut regions (anterior, middle and posterior) were processed for histological (cytochemistry and immunocytochemistry) and for ultrastructural analysis. Our results showed that the midgut of C. claveri for the three phases of the life cycle is of pseudostratified type, consisting of columnar cells, regenerative cells, and endocrine cells, morphological and ultrastructural differences in the epithelium allowed to characterize two regions, the anterior and posterior, they working mainly in the secretion and absorption respectively; the middle region has intermediate characteristics, and it is considered a transitional area. The ingestion of neem oil in the larval stage of C. claveri showed to be toxic to this predator, causing ultrastructural alterations... (Complete abstract click electronic access below)

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19

Scudeler, Elton Luiz. "Efeito do óleo de nim (Azadirachta indica A. Juss) no intestino médio de Ceraeochrysa claveri (Navás, 1911) (Neuroptera: Chrysopidae) : estudo citoquímico, imunocitoquímico e ultraestrutural /." Botucatu, 2012. http://hdl.handle.net/11449/99436.

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Orientador: Daniela Carvalho dos Santos
Banca: Hélio Conte
Banca: Daniela Oliveira Pinheiro
Resumo: Ceraeochrysa claveri, popularmente conhecido como bicho lixeiro, é um inseto predador de ovos e larvas de insetos pragas encontrados em diferentes ecossistemas agrícolas. O bicho lixeiro se destaca por apresentar potencial para ser utilizado em programas de Controle Biológico, uma vez que é predador na fase de larva, apresenta curto tempo de desenvolvimento, fácil criação massal e alto potencial reprodutivo na fase adulta. Com o propósito de aprofundar o conhecimento na morfologia e ultraestrutura do intestino médio de C. claveri, o objetivo deste trabalho foi caracterizar histológica e ultraestruturalmente o intestino médio de C. claveri no terceiro ínstar de larva, pupa e adulto. Objetivamos, ainda, avaliar o efeito da ingestão do óleo de nim (Azadirachta indica A. Juss) (Meliaceae) sobre as células epiteliais do intestino médio de larva de terceiro ínstar, pupa e adulto de C. claveri. Ovos de Diatraea saccharalis foram tratados com óleo de nim em três diferentes concentrações (0,5; 1 e 2%) e oferecidos como alimento a larvas de C. claveri durante todo período larval. Após coleta e fixação do intestino médio de larva, pupa e adulto (grupos controle e tratados com óleo de nim), as regiões do mesêntero (anterior, média e posterior) foram processadas para análise histológica (citoquímica e imunocitoquímica) e para análise ultraestrutural. Nossos resultados mostraram que o intestino médio de C. claveri, para as três fases do ciclo de vida, é do tipo pseudoestratificado, composto por células colunares, regenerativas e endócrinas; diferenças morfológicas e ultraestruturais no epitélio permitem caracterizar duas regiões, anterior e posterior, atuando respectivamente na secreção e absorção; região média apresenta características... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Ceraeochrysa claveri, popularly known as trash-carriers is a predator insect of eggs and larvae of insect pests found in different agroecosystems. The trash-carriers stands out because it has the potential to be used in biological control programs, once it is a predator in the larval stage; it has short developmental times, easy mass-rearing and high reproductive potential in adult stage. In order to deepen the knowledge on the morphology and ultrastructure of the midgut of C. claveri, the aim of this study was to characterize histological and ultrastructurally the midgut of C. claveri in the third instar larva, pupa and adult. We also evaluate the effect of ingestion of neem oil (Azadirachta indica A. Juss) (Meliaceae) on the midgut epithelial cells of third instar larva, pupa and adult of C. claveri. Diatraea saccharalis eggs were treated with neem oil at three different concentrations (0.5, 1 and 2%) and provided as food to larvae of C. claveri throughout the larval period. After collected and fixed the midgut of larva, pupa and adult (control and treated groups with neem oil), the midgut regions (anterior, middle and posterior) were processed for histological (cytochemistry and immunocytochemistry) and for ultrastructural analysis. Our results showed that the midgut of C. claveri for the three phases of the life cycle is of pseudostratified type, consisting of columnar cells, regenerative cells, and endocrine cells, morphological and ultrastructural differences in the epithelium allowed to characterize two regions, the anterior and posterior, they working mainly in the secretion and absorption respectively; the middle region has intermediate characteristics, and it is considered a transitional area. The ingestion of neem oil in the larval stage of C. claveri showed to be toxic to this predator, causing ultrastructural alterations... (Complete abstract click electronic access below)
Mestre

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Garriga, Oliveras Anna. "Entomopathogenic nematodes and Drosophila suzukii: from biological control to immunology perspective." Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/673764.

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Drosophila suzukii es una plaga invasora que ataca a fruits vermells, maduixes i cireres ja que les larves se’n alimenten abans de la maduració del fruit. En aquesta tesis s’avalua la potencialitat dels nematodes entomopatògens com agents de control biològic per controlar D. suzukii, al mateix temps que es determina el paper del sistema immunològic de l’insecte en front la infecció. En els dos primers capítols, s’analitza la susceptibilitat de les diferents etapes de desenvolupament de la mosca enfront dels nematodes Steinernema feltiae, Steinernema carpocapsae i Heterorhabditis bacteriophora en condicions de laboratori. Les larves són altament susceptibles a totes les espècies de nematodes emprades, en canvi no es va registrar cap infecció durant l’etapa de pupa. En la fase adulta només S. carpocapsae va ser capaç d’infectar aconseguint un percentatge d’infecció molt elevada en adults que acabaven d’emergir en comparació als adults madurs. A més també s’han dut a terme dues proves preliminars d’aplicació de nematodes sobre fruit i a terra en condicions de laboratori. Per tal de combinar l’aplicació de nematodes amb altres agents de control biològic com són insectes depredadors o parasitoids, en el tercer capítol s’han realitzat assajos de compatibilitat en placa de Petri i en planta. Aquests experiments han demostrat que els nematodes no han infectat els insectes beneficiosos en condicions de planta i podrien ser utilitzats conjuntament. El desenvolupament de la resposta immune en el procés infectiu de S. carpocapsae i el bacteri simbiont X. nematophila és desconegut en D. suzukii i per tant s’han enfocat dos capítols per l’estudi a nivell efectiu i regulador. Mitjançant assajos fisiològics i d’expressió gènica s’han avaluat 6 vies immunològiques incloent processos humorals, cel·lulars i d’activació global. Pel que fa la resposta humoral, no s’ha detectat una activació en presència del nematode i només s’han activat els gens de Toll i Imd quan s’ha alliberat el bacteri. A nivell efector va significar un augment de pèptids antimicrobians en l’hemolimfa, tot i que la seva activitat va ser bloquejada per l’acció del bacteri. A nivell cel·lular, el nematode tampoc va ser reconegut pels receptors corresponents i no es van activar ni la via Jak/STAT ni proPO. Per tant els hemòcits no es van activar i no es va detectar ni encapsulació del nematode ni fagocitosi del bacteri. A més sense l’activació de les cèl·lules cristal·lines tampoc s’allibera l’enzim fenol-oxidasa i no es pot desenvolupar la resposta de melanització. Igualment s’ha descrit com en presència de X. nematophila, l’enzim presenta una baixada d’activitat en l’hemolimfa. Finalment, JNK i TGF-β són vies relacionades amb l’activació global en condicions d’estrès que no s’han vist alterades per la infecció nematode-bacteriana. Aquests resultats mostren els mecanismes emprats pel complex S. carpocapsae - X. nematophila per superar les defenses de l’insecte. Aquesta tesis engloba la relació entre nematodes entomopatògens i D. suzukii establint les bases de susceptibilitat amb les quals desenvolupar una estratègia de control biològic, i el coneixement del procés infectiu entre hoste i patogen.
Drososphila suzukii es una plaga invasora que ataca a frutos rojos, fresas y cerezas ya que las larvas se alimentan antes de la maduración del fruto. En esta tesis se evalúa la potencialidad de los nematodos entomopatógenos como agentes de control biológico para controlar D. suzukii, a la vez que se determina el papel del sistema inmunológico del insecto frente a la infección. En los dos primeros capítulos, se analiza la susceptibilidad de las etapas de desarrollo de la mosca frente a los nematodos Steinernema feltiae, Steinernema carpocapsae y Heterorhabditis bacteriophora en condiciones de laboratorio. Las larvas son altamente susceptibles a todas las especies de nematodo usadas, en cambio no se registró ninguna infección durante la etapa de pupa. En la fase adulta solo S. carpocapsae fue capaz de infectar, consiguiendo un porcentaje de infección elevado en adultos que acaban de emerger en comparación con adultos maduros. Además, también se realizaron dos pruebas preliminares de aplicación de nematodos en fruto y tierra en condiciones de laboratorio. Para combinar la aplicación de nematodos con otros agentes de control biológico como son insectos depredadores y parasitoides, en el tercer capítulo se han realizado ensayos de compatibilidad en placa de Petri y en planta. Estos experimentos han demostrado que los nematodos no han infectado los insectos beneficiosos en condiciones de planta y podrían ser usados conjuntamente. El desarrollo de la respuesta inmune en el proceso infectivo de S. carpocapsae y la bacteria simbionte X. nematophila es desconocido en D. suzukii y por lo tanto se ha abordado en dos capítulos el estudio a nivel efectivo y regulador. Mediante ensayos fisiológicos y de expresión génica se han evaluado 6 vías inmunológicas incluyendo procesos humorales, celulares i de activación global. En la respuesta humoral no se detectó una activación en presencia del nematodo y solo se activaron los genes Toll y Imd cuando fue liberada la bacteria. A nivel efector eso significó un aumento de péptidos antimicrobianos en hemolinfa, a pesar de que su actividad fue bloqueada por la acción de la bacteria. A nivel celular, el nematodo tampoco fue reconocido por los receptores correspondientes i no se activó ni la vía Jak/STAT ni proPO. Por lo tanto, los hemocitos no se activaron y no se encapsularon los nematodos ni fagocitó la bacteria. Además, sin la activación de las células cristalinas tampoco se liberó la enzima fenol-oxidasa y no se pudo desarrollar la respuesta de melanización. Igualmente se ha descrito como en presencia de X. nematophila, la enzima presenta una bajada de actividad en hemolinfa. Finalmente, JNK y TGF-β son vías relacionadas con la activación global en condiciones de estrés que no se han alterado por la infección. Estos resultados muestran los mecanismos usados por el complejo S. carpocapsae – X. nematophila para superar las defensas del insecto. Esta tesis engloba la relación entre nematodos entomopatógenos y D. suzukii estableciendo las bases de susceptibilidad con las cuales desarrollar una estrategia de control biológico, y el conocimiento del proceso infectivo entre huésped y patógeno.
Drosophila suzukii is an invasive pest that attacks berries, strawberries, and cherries because larvae feed from ripen fruit causing great losses. In this thesis, the potentiality of entomopathogenic nematodes as biological control agents was evaluated to control D. suzukii, as well as to determine the role of insect’s immune system against infection. In the two first chapters, we studied the susceptibility of the developmental stages of the fly against the nematodes Steinernema feltiae, Steinernema carpocapsae and Heterorhabditis bacteriophora under laboratory conditions. Larvae were highly susceptible to all tested nematodes, although no infection was detected during pupal stage. In the adult stage, only S. carpocapsae managed to infect the fly with a high percentage of infection in teneral adults (newly emerged) compared to mature adults. Moreover, two preliminary tests of nematode application were carried out in fruit and soil under laboratory conditions with promising results. In order to perform combined application of nematodes and other biological control agents such as insect predators and parasitoids, in the third chapter, compatibility experiments were done in Petri dish and plant pot. These assays showed no infection of nematodes to the beneficial insects under plant pot conditions. Thus, these agents could be used together. The development of the immune response to the infective process of S. carpocapsae and the symbiont bacteria X. nematophila was unknown in D. suzukii. For this reason, two chapters were focused on the immune study at effective and regulatory level. Through physiological and gene expression assays, 6 immune pathways were studied including humoral and cellular processes, and global activation. Regarding the humoral response, there was no activation under nematode presence and the upregulation of Toll and Imd genes happened only after bacterial release. At the effector level these resulted in an increase of antimicrobial peptides in haemolymph, although the activity was supressed by the bacteria. At cellular level, nematodes were not recognised by the receptors and Jak/STAT and proPO were not activated in response. In consequence, haemocytes were unactive and neither encapsulation of nematodes nor phagocytosis of bacteria was detected. Moreover, without the activation of crystal cells, there was no release of phenol-oxidase enzyme and the fly was unable to develop the melanization response. With the presence of X. nematophila, the enzyme presented a reduced activity in haemolymph too. Finally, JNK and TGF-β are pathways related to global activation under stress conditions, but these presented no variations under nematode-bacterial infection. These results showed the mechanisms used by the complex S. carpocapsae – X. nematophila to overcome the insect defences. This thesis encompasses the relation between entomopathogenic nematodes and D. suzukii establishing the susceptibility baseline to develop a biological control strategy and the knowledge of the infective process between host and pathogen.
Universitat Autònoma de Barcelona. Programa de Doctorat en Biodiversitat

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Potgieter, Linke. "A mathematical model for the control of Eldana saccharina Walker using the sterile insect technique." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85865.

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Thesis (PhD)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Two mathematical models are formulated in this dissertation for the population growth of an Eldana saccharina Walker infestation of sugarcane under the influence of partially sterile released insects. The first model describes the population growth of and interaction between normal and sterile E. saccharina moths in a temporally variable, but spatially homogeneous environment. The model consists of a deterministic system of difference equations subject to strictly positive initial data. The primary objective of this model is to determine suitable parameters in terms of which the above population growth and interaction may be quantified and according to which E. saccharina infestation levels and the associated sugarcane damage may be measured. The second model describes this growth and interaction under the influence of partially sterile insects which are released in a temporally variable and spatially heterogeneous environment. The model consists of a discretized reaction-diffusion system with variable diffusion coefficients, subject to strictly positive initial data and zero-flux Neumann boundary conditions on a bounded spatial domain. The primary objectives in this case are to establish a model which may be used within an area-wide integrated pest management programme for E. saccharina in order to investigate the efficiency of different sterile moth release strategies in various scenarios without having to conduct formal field experiments, and to present guidelines by which release ratios, frequencies and distributions may be estimated that are expected to lead to suppression of the pest. In addition to the mathematical models formulated, two practical applications of the models are described. The first application is the development of a user-friendly simulation tool for simulating E. saccharina infestation under the influence of sterile insect releases over differently shaped spatial domains. This tool provides the reader with a deeper understanding as to what is involved in applying mathematical models, such as the two described in this dissertation, to real-life scenarios. In the second application, an optimal diversification of sugarcane habitats is considered as an option for minimising average E. saccharina infestation levels, and as a further consequence, improving the cost-efficiency of sterile insect releases. Although many special cases of the above model classes have been used to model the sterile insect technique in the past, few of these models describe the technique for Lepidopteran species with more than one life stage and where F1-sterility is relevant. In addition, none of these models consider the technique when fully sterile females and partially sterile males are being released. The models formulated in this dissertation are also the first to describe the technique applied specifically to E. saccharina, and to consider the economic viability of applying the technique to this species. Furthermore, very few examples exist of such models which go beyond a theoretical description and analysis towards practical, real-life applications as illustrated in this dissertation.
AFRIKAANSE OPSOMMING: Twee wiskundige modelle word in hierdie proefskrif vir die populasiegroei van ’n Eldana saccha- rina Walker infestasie van suikerriet onder die invloed van gedeeltelik steriele, vrygelate insekte daargestel. Die eerste model beskryf die populasiegroei van en -interaksie tussen normale en steriele E. saccharina motte in ’n dinamiese, maar ruimtelik-homogene omgewing. Die model is ’n stelsel deterministiese verskilvergelykings onderhewig aan streng positiewe aanvangswaardes. Die primˆere doelstelling met hierdie model is om geskikte parameters te bepaal in terme waarvan die bogenoemde groei en interaksie gekwantifiseer kan word, en waarvolgens E. saccharina infestasievlakke en die gepaardgaande suikerrietskade gemeet kan word. Die tweede model beskryf hierdie groei en interaksie onder die invloed van gedeeltelik steriele insekte wat in ’n dinamiese en ruimtelik-heterogene omgewing vrygelaat word. Die model is ’n gediskretiseerde stelsel reaksie-diffusievergelykings met veranderlike diffusieko¨effisi¨ente onderhewig aan streng positiewe aanvangswaardes en zero-vloei Neumann-randwaardes op ’n begrensde ruimtelike gebied. Die primˆere doelstellings in hierdie geval is om ’n model tot stand te bring wat in ’n area-wye, ge¨ıntegreerde pesbestrydingsprogram vir E. saccharina gebruik kan word om die doeltreffendheid van verskillende steriele motvrylatingstrategie¨e te bepaal sonder om daadwerklik veldeksperimente uit te voer, en om riglyne daar te stel waarvolgens vrylatingsverhoudings, -frekwensies en -verspreidings bepaal kan word wat na verwagting na ’n onderdrukking van die pes sal lei. Bykomend tot die wiskundige modelle in hierdie proefskrif, word twee praktiese toepassings van die modelle ook beskryf. In die eerste toepassing word ’n gebruikersvriendelike simulasie hulpmiddel ontwikkel om E. saccharina infestasie onder die invloed van steriele insekvrylatings in verskillende ruimtelike gebiede te simuleer. Hierdie toepassing fasiliteer ’n dieper begrip van wat ter sprake is in die toepassing van wiskundige modelle, soos die twee modelle in hierdie tesis, tot werklike scenario’s. In die tweede toepassing word ’n optimale diversifisering van suikerriet habitats as ’n opsie vir die vermindering van die gemiddelde E. saccharina infestasie vlakke beskou, en gevolglik word die verbetering van die koste-doeltreffendheid van steriele insekvrylatings afgeskat. Alhoewel verskeie spesiale gevalle van die bogenoemde twee klasse van modelle reeds in die verlede gebruik is om die doeltreffendheid van die steriele-insektegniek te modelleer, beskryf weinig van hierdie modelle die tegniek vir Lepidopteriese spesies met meer as een lewensfase en waar F1-steriliteit ter sprake is. Verder beskryf geen van hierdie modelle die tegniek waar algeheel steriele wyfies en gedeeltelik steriele mannetjies vrygelaat word nie. Die modelle in hierdie tesis is ook die eerste waar die tegniek spesifiek op E.saccharina toegepas word, en waar die ekonomiese lewensvatbaarheid van die tegniek vir hierdie spesie oorweeg word. Verder bestaan daar min voorbeelde van soortgelyke modelle wat verder gaan as ’n teoretiese beskrywing en wiskundige ontleding na praktiese, werklike toepassings, soos in hierdie proefskrif ge¨ıllustreer.

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22

Martel, John W. "Development of Semiochemical-Based Strategies for Management of Colorado Potato Beetle, Leptinotarsa decemlineata (Say)." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/MartelJW2004.pdf.

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23

Magalhães, Gustavo Oliveira de. "Aspectos biológicos de Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae) e estratégias para o manejo da praga /." Jaboticabal, 2016. http://hdl.handle.net/11449/142829.

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Orientador: Sergio Antonio De Bortoli
Banca: Fernando Hercos Valicente
Banca: Roberto Marchi Goulart
Banca: Ricardo Antonio Polanczyk
Banca: Nilza Maria Martinelli
Resumo: O objetivo deste trabalho foi avaliar a biologia de linhagens de P. xylostella em criações para fins de pesquisa e verificar o efeito de B. thuringiensis sobre P. nigrispinus em associação de métodos para o manejo da praga em ambiente protegido. As larvas de P. xylostella foram coletadas em Brassica oleracea var. italica - brócolis Piracicaba, e mantidas em Brassica oleracea var. acephala - couve Manteiga híbrida HS-20. A cada geração aspectos biológicos dos insetos foram avaliados em ensaios de laboratório. As características biológicas analisadas foram: período larval, viabilidade de larvas, período pupal, viabilidade de pupas, peso pupal, razão sexual, número de ovos por fêmea, fertilidade de ovos, longevidade de machos e longevidade de fêmeas. Também, com os dados obtidos foi construída a tabela de vida de fertilidade. Já com predador, P. nigrispinus, foi avaliada a história de vida, o consumo de lagartas de P. xylostella em plantas de couve tratadas com bioinseticidas à base de Bacillus thuringiensis e também sua atividade de fitofagia nestas plantas, em casa de vegetação. Nas avaliações de P. xylostella, indivíduos coletados no campo apresentaram duração larval (8,2 dias) e pupal (3,8 dias) maiores, diminuindo ao longo de gerações. A viabilidade pupal (86,9%) e a fertilidade (93,0%) também foram maiores para essa população, com menor peso de pupa (4,7 mg). Além disso, apresentaram menor taxa líquida de aumento populacional (Ro), com 39 fêmeas/fêmea/dia, enquanto que, na... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This study aimed to evaluate the biology of P. xylostella strains in mass rearing for research and verify the effects of B. thuringiensis on P. nigrispinus in association methods for the management of this pest in protected environment. Larvae collected from Brassica oleracea var. italica - broccoli Piracicaba, were kept in Brassica oleracea var. acephala - kale Manteiga hibrida HS-20. The biological aspects of insects generations were evaluated in laboratory bioassays. The biological parameters evaluated were: larval period, larval viability, pupal period, pupal viability, pupal weight, sex ratio, number of eggs per female, eggs fertility, longevity of males and females. The data were used to construc of a life table fertility. The predator consuming P. xylostella larvae in kale plants treated with bionsecticides based on Bacillus thuringiensis and also their phytophagy activity in these plants, in green house was evaluated. The individuals collected in the field presented larval period (8.2 days) and pupal (3.8 days) longer, decreasing over generations. 86.9% of pupal viability and 93.0% of fertility were also high in this population, however prepal weight was significanthy low (4.7 mg). In addition, the lower net rate of population increase (Ro) with 39 females / female / day, whereas in P. xylostella population from the laboratory was 47.8 females / female / day. In general, the biological characteristics of predators did not change when the predators consumed prey direct... (Complete abstract click electronic access below)
Doutor

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Coombes, Candice Anne. "Entomopathogenic fungi for control of soil-borne life stages of false codling moth, Thaumatotibia leucotreta (Meyrick) (1912) (Lepidoptera: Tortricidae)." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1002057.

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False codling moth (FCM), Thaumatotibia leucotreta is an extremely important pest of citrus in South Africa and with the shift away from the use of chemicals, alternate control options are needed. One avenue of control which has only recently been investigated against the soil-borne life stages of FCM is the use of entomopathogenic fungi (EPF). In 2009, 12 entomopathogenic fungal isolates collected from South African citrus orchards showed good control potential during laboratory conducted bioassays. The aim of this study was to further analyse the potential of these isolates through concentration-dose and exposure-time response bioassays. After initial re-screening, concentration-dose response and exposure-time response sandconidial bioassays, three isolates were identified as exhibiting the greatest control potential against FCM in soil, Metarhizium anisopliae var. anisopliae (G 11 3 L6 and FCM Ar 23 B3) and Beauveria bassiana (G Ar 17 B3). Percentage mycosis was found to be directly related to fungal concentration as well as the amount of time FCM 5th instar larvae were exposed to the fungal conidia. LC50 values for the three isolates were not greater than 1.92 x 10⁶ conidia.ml⁻ₑ and at the LC₅₀, FCM 5th instar larvae would need to be exposed to the fungus for a maximum of 13 days to ensure a high mortality level. These isolates along with two commercially available EPF products were subjected to field persistence trials whereby net bags filled with a mixture of autoclaved sand and formulated fungal product were buried in an Eastern Cape citrus orchard. The viability of each isolate was measured on a monthly basis for a period of six months. All isolates were capable of persisting in the soil for six months with the collected isolates persisting far better than the commercially used isolates. Two of the isolates, G 11 3 L6 and G Ar 17 B3, were subjected to small scale laboratory application trials. Two formulations were investigated at two concentrations. For each isolate, each formulation and each concentration, FCM 5th instar larvae were applied and allowed to burrow into the soil to pupate before fungal application or after fungal application. Contact between fungi and FCM host is essential as, in contrast to pre-larval treatments, percentage mortality in post-larval treatments was low for both formulations and both isolates. For isolate G Ar 17 B3, a conidial suspension applied as a spray at a concentration of 1 x 10⁷ conidia.ml⁻ₑ obtained the highest percentage mortality (80 %). For isolate G 11 3 L6 however, both formulations performed equally well at a high, 1 x10⁷ conidia.ml⁻ₑ concentration (conidial suspension: 60 %; granular: 65 %) The results obtained thus far are promising for the control of FCM in citrus, but if these EPFs are to successfully integrate into current FCM control practices more research, some of which is discussed, is essential

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Barnewall, Emily C., and University of Lethbridge Faculty of Arts and Science. "Plant-insect interactions between yellow toadflax, Linaria vulgaris, and a potential biocontrol agent, the gall-forming weevil, Rhinusa pilosa." Thesis, Lethbridge, Alta. : University of Lethbridge, Department of Biological Sciences, c2011, 2011. http://hdl.handle.net/10133/2618.

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Yellow toadflax, Linaria vulgaris (L.) Mill. (Plantaginaceae), is a non-native invasive plant. Rhinusa pilosa Germar (Coleoptera: Curculionidae) is a proposed biocontrol agent. Gall development by R. pilosa was described using histological methods and compared between plant populations from native and introduced ranges. Key stages of oviposition were isolated histologically to determine their importance in gall induction. Rhinusa pilosa galled and developed on four geographically distinct Canadian populations in a pre-release quarantine study. Low agent densities only negatively affected one population. High densities of R. pilosa reduced potential reproductive output and plant biomass. Conducting detailed investigations into the biology, impact, and development of R. pilosa on populations from invasive and native ranges may help predict the efficacy of R. pilosa in the field if approved for release and.goes beyond current pre-release testing requirements.
ix, 168 leaves : ill. (chiefly col.) ; 29 cm

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Weyl, Philip Sebastian Richard. ""Is more, less?" : insect-insect interactions in a biological control context using water hyacinth as a model." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1005410.

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Interactions between insects have been shown to be important regulators of population abundances and dynamics as well as drivers of spatial segregation and distribution. These are important aspects of the ecology of insects used in biological control and may have implications for the overall success of a particular programme. In the history of biological control there has been a tendency to release a suite of agents against a weed, which in some cases has increased the level of success, while in others little change has been observed. In most of these cases the implications of increasing the level of complexity of the system is not taken into account and there is little research on the effect of releasing another agent into the system. A brief meta-analysis was done on all the biological control programmes initiated in South Africa. Emphasis was placed on multi-species releases and the effects that overlapping niches were having on the number of agents responsible for the success of a programme. Where overlapping niches were present among agents released the number of agents responsible for success was lower than the number established. Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach in South Africa has more arthropod agents released against it than anywhere else in the world, yet control has been variable. If the biology and host utilisation of all the agents against water hyacinth is considered, a definite overlap of niches is apparent in at least one life stage of all the agents. Therefore the probability of these insects interacting is high, especially if they are established at the same site in the field. Three of the insects released in South Africa have been selected to investigate possible interactions. They are Neochetina eichhorniae Warner, Neochetina bruchi Hustache and Eccritotarsus catarinensis (Carvalho). Y-tube olfactometer bioassays were used to measure responses of these insects to water hyacinth with prior feeding damage by either conspecifics or heterospecifics. This was done to determine whether olfactory cues played a role in host acceptability and avoidance of conspecifics or heterospecifics. The insects were given a choice between damaged and undamaged plants in various combinations. There was a significant preference for the undamaged plants when given a choice between undamaged and damaged plants. However when the insects were given a choice between two damaged plants there was no discrimination between heterospecific or conspecific damaged plants. This may indicate that there is little or no ecological cost for the insect to share a plant with other insects utilising a similar resource. Insect – insect interactions were investigated in a common garden plot experiment to measure the impact that pairwise combinations of the insect may have on their performance. There was a significant interaction between the mirid E. catarinensis and the weevil N. eichhorniae, with the weevil not performing as well when in combination with the mirid than when alone. Interestingly there was a negative interaction between the two weevil species when in combination, however it was impossible to determine which species was being affected if not both. None of the insects performed significantly better when in combination with another insect. A field study on Wriggleswade Dam in the Eastern Cape, South Africa was initiated to determine whether the relationship between the mirid E. catarinensis and the weevil N. eichhorniae could be determined in the field. The performance of the insects at the different sites in the field suggests that there was an interaction between the agents. This interaction did not limit the establishment of either insect at a site, but it did result in one insect dominating at a site over another. Interactions between the three species of insect tested in this thesis suggest that there are both negative and neutral relationships between them. A basic comparison between the insect performances from 15 sites around the country was done to determine if the spatial segregation observed in the field could be extrapolated to the natural South African situation. The interaction observed between N. eichhorniae and E. catarinensis does seem to extrapolate to the general South African situation where there is definite spatial segregation on a landscape level. The co–occurrence of the two Neochetina weevils at these sites suggests that the negative relationship observed between them in the common garden experiment does not extrapolate to the field. The results from this thesis suggest that the interactions between the agents tested would not limit establishment or have significant ramifications on performance. However, there may be spatial and temporal segregation of these species in the introduced range.

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Cattaneo, Alberto Maria. "Unveiling sensory mechanisms for the control of two insect pests: from behaviour to molecular interactions." Doctoral thesis, country:IT, 2015. http://hdl.handle.net/10449/29924.

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Pest control strategies targeting insect olfaction represent a promising venue for control of tortricid insects (Lepidoptera: Tortricidae). Among tortricids, the grapevine moth Lobesia botrana (Denis and Schiffermüller) and the codling moth Cydia pomonella (L.) are serious pests for worldwide production of fruit crops. We employed several approaches to the olfactory system, from electrophysiological and behavioral studies in the grapevine moth, to bioinformatic and molecular studies of olfactory sensory proteins in the codling moth. At the receptor level, we studied both the Olfactory Receptors (ORs), the most common class of sensory proteins mediating detection of odors in insect antennae, and the Transient Receptor Potential (TRP) channels, a novel family of receptor, that recently were also found in the antennae of lepidopterous species. We demonstrated electrophysiological and behavioral responses of the grapevine moth to volatiles emitted by a non-host, Perilla frutescens, previously known to activate TRPs in the rat, Rattus norvegicus. In the codling moth, we characterized a novel TRP channel (TRPA pyrexia-like) and we confirmed activation of its human orthologue to the same non-host compounds active on the olfactory system of the grapevine moth. ORs were heterologously expressed in vivo and in vitro, for identification of their ligands among host and non-host plant volatiles and pheromones (deorphanization). Among several ORs of codling moth, we deorphanized a candidate pheromone receptor (PR) to plant synergists, an OR to non-host volatiles and another PR candidate to a pheromone antagonist of the insect. Our study thus opens for refinement of existing pest control, or novel applications. The behavioral response of the grapevine moth to volatiles from a nonhost plant, and the identification of a novel TRP channel in the codling moth may have perspectives for application in agriculture, targeting the somatosensory system of these tortricids. The evolutionary implications of the responses of the human orthologue of TRPA pyrexia-like to volatiles active on the grapevine moth olfactory system could imply a large degree of conservation of the receptor function. In the codling moth, identification of synergist and antagonist ligands for candidate PRs and deorphanization of an OR to non-host plant volatiles suggest a possible role of these receptors in reproductive and ecological isolation. This could lead to further refinement of existing semiochemicalbased control techniques, by enabling a better understanding of mate- and host-finding in this species.

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Cattaneo, A. M. "UNVEILING SENSORY MECHANISMS FOR THE CONTROL OF TWO INSECT PESTS: FROM BEHAVIOR TO MOLECULAR INTERACTIONS." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/347230.

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Pest control strategies targeting insect olfaction represent a promising venue for control of tortricid insects (Lepidoptera: Tortricidae). Among tortricids, the grapevine moth Lobesia botrana (Denis and Schiffermüller) and the codling moth Cydia pomonella (L.) are serious pests for worldwide production of fruit crops. We employed several approaches to the olfactory system, from electrophysiological and behavioral studies in the grapevine moth, to bioinformatic and molecular studies of olfactory sensory proteins in the codling moth. At the receptor level, we studied both the Olfactory Receptors (ORs), the most common class of sensory proteins mediating detection of odors in insect antennae, and the Transient Receptor Potential (TRP) channels, a novel family of receptor, that recently were also found in the antennae of lepidopterous species. We demonstrated electrophysiological and behavioral responses of the grapevine moth to volatiles emitted by a non-host, Perilla frutescens, previously known to activate TRPs in the rat, Rattus norvegicus. In the codling moth, we characterized a novel TRP channel (TRPA pyrexia-like) and we confirmed activation of its human orthologue to the same non-host compounds active on the olfactory system of the grapevine moth. ORs were heterologously expressed in vivo and in vitro, for identification of their ligands among host and non-host plant volatiles and pheromones (deorphanization). Among several ORs of codling moth, we deorphanized a candidate pheromone receptor (PR) to plant synergists, an OR to non-host volatiles and another PR candidate to a pheromone antagonist of the insect. Our study thus opens for refinement of existing pest control, or novel applications. The behavioral response of the grapevine moth to volatiles from a nonhost plant, and the identification of a novel TRP channel in the codling moth may have perspectives for application in agriculture, targeting the somatosensory system of these tortricids. The evolutionary implications of the responses of the human orthologue of TRPA pyrexia-like to volatiles active on the grapevine moth olfactory system could imply a large degree of conservation of the receptor function. In the codling moth, identification of synergist and antagonist ligands for candidate PRs and deorphanization of an OR to non-host plant volatiles suggest a possible role of these receptors in reproductive and ecological isolation. This could lead to further refinement of existing semiochemicalbased control techniques, by enabling a better understanding of mate- and host-finding in this species.

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Costa, Suzana Regina Silveira. "Caracterização molecular de populações do inseto praga psilídeo de concha (Glycaspis brimblecombei) por meio de marcadores do tipo ITS 1 (Internal Tanscribed Spacer 1) /." Botucatu : [s.n.], 2011. http://hdl.handle.net/11449/92450.

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Orientador: Celso Luis Marino
Banca: Denise Selivon
Banca: Carlos Frederico Wilcken
Resumo: O gênero Eucalyptus é originário da Austrália e está estabelecido no Brasil há mais de um século. Atualmente, o Brasil tem a segunda maior área plantada, formando monoculturas, que favorecem o estabelecimento de insetos praga. No ano de 2003 foi verificada pela primeira vez no país a ocorrência de Glycaspis brimblecombei, espécie descrita por Moore (Hemiptera, Psyllidae). Tal espécie também é conhecida por psilídeo de concha, em plantios de Eucalyptus sp. no estado de São Paulo. Devido sua alta capacidade adaptativa, atualmente se encontra amplamente distribuído por todo território nacional. Os danos causados por sua infestação são inúmeros, resultando em perdas consideráveis para o setor florestal e consequentemente para a economia brasileira. As populações do psilídeo de concha apresentam baixa variação morfológica, dificultando sua identificação; assim, análises moleculares, tais quais o uso de marcadores, podem auxiliar a responder essas questões. Um marcador amplamente utilizado, por sua alta variabilidade, é o espaçador interno transcrito do DNA ribossomal (ITS). Deste modo, o marcador ITS foi utilizado neste trabalho para averiguar a dinâmica populacional do psilídeo de concha de quatro regiões do estado de São Paulo. A sequência do ITS1 apresentou um intervalo de 291 pb em 88,73% das amostras. Os sítios polimórficos foram identificados no intervalo de 80 a 200 pb, sendo que na população de Pedra Bela foi observada a maior distribuição destes. Além disso, observou-se a ocorrência de seis haplótipos distribuídos nas quatro populações. O haplótipo 1 esteve presente em todas as populações, enquanto que o haplótipo 6 foi somente identificado na população de Criação de Laboratório. A diversidade nucleotídica (Pi) das populações foi de 0,00445, sendo que a de Criação de Laboratório... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Eucalyptus genus is derived from Australia and is settled in Brazil for more than a century now. Currently, Brazil has the second largest planted area, forming monocultures that smooth infestation with pest-insects. In 2003, the occurrence of Glycaspis brimblecombei, species described by Moore (Hemiptera, Psyllidae), was detected in Brazil for the first time. The said species is also known as red gum lerp, in Eucalyptus sp plantations in the State of São Paulo. Because of their high capacity of adaptation, nowadays they are found widely distributed all over the domestic territory. Damages caused by their infestation are numerous, resulting in considerable losses for the forestry sector and, consequently, for the Brazilian economy. Red gum lerp populations present a low rate of morphological variation, which makes their identifiction more difficult. Accordingly, molecular tests, such as the use of markers, may help answering such questions. A widely used marker, due to its high variability, is the internal transcribed spacer of ribosomal DNA (ITS). Thus, the ITS marker was used in this paper to investigate the population dynamics of red gum lerps from four regions in the State of São Paulo. ITS1 sequence showed a range of 291 bp in 88.73% of the samples. Polymorphic sites were identified in the range of 80-200 bp, with the population from Pedra Bela showing the highest distribution. Moreover, the occurrence of six haplotypes distributed in the four populations was found. Haplotype 1 was present in all populations, while haplotype 6 was identified in lab-developed population only. The nucleotide diversity (Pi) of populations was 0.00445, while the lab-developed population showed the highest Pi value as between the four populations. In Botucatu, no diversity was found. Specific oligonucleotides flanking the polymorphic regions of the... (Complete abstract click electronic access below)
Mestre

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Robinson, Peter. "Physiological studies on the aphid pathogen Erynia neoaphidis with a view to its use as a biological control agent in the field." Thesis, King's College London (University of London), 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283833.

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31

Wallage, Helena Rachelle. "The effects of Plagiorchis elegans (Trematoda : Plagiorchiidae) infection on the carbohydrate metabolism of fourth instar Aedes aegypti (Diptera : Culicidae) larvae." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30763.

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Glucose was present in substantially greater concentrations in whole body extracts of fourth instar Aedes aegypti L. larvae than was trehalose; in contrast, trehalose was more abundant than glucose in haemolymph extracts. Preliminary studies suggested that infection of Ae. aegypti by the entomopathogenic digenean Plagiorchis elegans Rudolphi alters the carbohydrate metabolism of fourth instar larvae. Within 24 hours of cercarial penetration, total body extracts of infected fourth instar larvae exhibited decreased trehalase activity, increased trehalose-6-phosphatase activity, and an accumulation of trehalose in comparison to uninfected larvae. Concentrations of glucose, glycogen and lipids, and the activity of glycogen phosphorylase a were similar in extracts of infected and control larvae. The predominant fatty acids, in both control and infected larvae, were C 18:0, C 18:1 and C 18:3. There were no significant differences in the types and proportions of fatty acids found in control and infected larvae. Parasitic infection is discussed in terms of impaired trehalose metabolism.

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Smith, Tamara Jane. "The diamondback moth, Plutella xylostella (L.), (Lepidoptera: Plutellidae) and its biological control in the Eastern Cape Province, South Africa." Thesis, Rhodes University, 2003. http://hdl.handle.net/10962/d1004742.

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The diamondback moth, Plutella xylostella (L.), is a pest on crucifer crops worldwide, damaging the leaves, florets and seed pods of many crucifers including cabbage, cauliflower, broccoli and canola. It has been controlled using broad-spectrum insecticides, but this has led to a rapid build-up of insecticide resistance. In the Grahamstown area of the Eastern Cape Province, South Africa, diamondback moth showed resistance to cypermethrin (a pyrethroid) on commercially grown cabbages. Therefore it is imperative that other methods of control be adopted, including both cultural control and biological control using parasitoids, and that these are incorporated into an Integrated Pest Management (IPM) programme. The diamondback moth and its parasitoids were monitored weekly from April 1997 to November 1999 at three sites near Grahamstown. One site was a commercial farm with an active insecticide spraying program; the others were unsprayed. Infestation levels were highest during spring (September to November) and autumn (March to May). Nine species of parasitoids were associated with the diamondback moth, with abundances being highest over spring and early summer (September to December). Cotesia plutellae (Kurdjumov) dominated the sprayed site, while the unsprayed sites yielded a complex of parasitoids, including C. plutellae, Diadegma mollipla (Holmgren), Diadromus collaris Gravenhorst and Oomyzus sokolowsldi (Kurdjumov). Parasitism levels ranged between 10 and 90%. There was a large amount of site-to-site and year-to-year variation. Parasitoids were an effective mortality factor against the diamondback moth. The effects of temperature on development and mortality, and of field size and non-crop plants on the distribution of diamondback moth and its parasitoids, were investigated. The results show that high temperatures can depress pest populations, and that the size and surroundings of fields can be manipulated to improve cultural control of the diamondback moth. Suggestions for effective rPM in the Eastern Cape Province include a reduction in insecticide applications, the use of bioinsecticides, for example Bacillus thuringiensis Berliner (Bt) and the encouragement of indigenous parasitoids by planting suitable nectar sources. Cultural control methods are also important and involve removal of cabbage refuse after harvest, management of wild crucifers around cabbage fields, scouting and monitoring the moth population and determining the optimal field size to assist with control by parasitoids.

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Fairbairn, Jonathan Paul. "Spatial and temporal dynamics of entomopathogenic nematodes." Thesis, University of Stirling, 2001. http://hdl.handle.net/1893/26685.

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The life-history and infection parameters of the entomopathogenic nematodes Steinernema feltiae (Filipjev)(Nematoda:Rhabditida) and Heterorhahditis megidis (Poinar, Jackson & Klein)(Nematoda:Rhabditida) were examined to provide specific details for the construction of mathematical SI models for biological control of soil insect pests. Laboratory experiments using the Greater Waxmoth, Galleria mellonella as the model host were undertaken to specifically examine the transmission behaviour of infective juvenile nematodes. The proportion of infective juveniles of S. feltiae which infected hosts was dependent on time. Previous studies declared that the proportion of infective juveniles which can infect is static, however, over a period of 5 days most of the infective juveniles infected hosts, demonstrating that the proportion infecting is dynamic. Infection of hosts by both species of nematode was compared using two mathematical representations of the transmission rate. Whereas the most parsimonious form of transmission for H. megidis was the linear Mass Action function, it was evident that, when measured at the individual nematode scale, S. feltiae transmission was non-linear. I postulated that this functional difference is due to the biology of the two species of nematodes. The subsequent effect of including the non-linear response on model predictions were investigated and it was demonstrated that the dynamics of the host nematode interaction became less stable. Spatial models of S. feltiae infection were parameterised from laboratory experiments, and control prediction of these models examined. The horizontal rate of dispersal through sand columns was determined in the presence and absence of hosts. Infective juveniles were found to disperse preferentially towards hosts. The predicted dynamics of pest control using the spatial moqel were highly dependent on the degree of nematode dispersal, host dispersal and the attraction of nematode infective juveniles towards hosts. The overall findings of this thesis have been placed in the context of epidemiological models created elsewhere, and predict that entomopathogenic nematodes may be targeted to specific pest systems with a high degree of success. An understanding of the infection biology of these nematode species is crucial in determining how and when pests may be controlled, and equally importantly, which systems successful control is not predicted.

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Love, Claire Natalie. "The biology, behaviour and survival of pupating false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a citrus pest in South Africa." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1018907.

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Control of the citrus pest, false codling moth (FCM), Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae) is crucial for the South African citrus industry. The economic losses and phytosanitary status of this pest, coupled with increased consumer awareness and demands, has created a need for effective, IPM-compatible control measures for use against the soil-dwelling life stages of FCM. Promising developments in the field of microbial control through the use of entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPNs) have highlighted the need for research regarding pupation biology, behaviour and survival of FCM, as a good understanding of biology of the target organism is an important component of any biological control programme. The aim of this study was to improve the current understanding of FCM pupation habits through the manipulation of soil texture class, ground cover, shading, soil compaction, air temperature, and soil moisture in the laboratory. These findings would then be used to aid the biological control programmes using EPF and EPNs against FCM in the soil. Three soil texture classes (sandy loam, silt loam and silty clay loam) were obtained from orchards for use in the study. FCM larvae were allowed to drop into the soil of their own accord and the pupation behaviour that followed was then captured on film with pupae formed in the soil being kept in order to measure adult eclosion. In general, very few abiotic factors had a clear influence on FCM pupation. Larval wandering time and distance was short, but also variable between individuals. Distance did increase when soils were moist. Pupation depth was shallow, with pupal cocoons generally being formed on the soil surface. Depth of pupation was less than one centimetre for all abiotic conditions, with little burrowing into soil. Eclosion success was higher for sandier soils when these were dry and uncompacted, but the addition of both moisture and soil compaction increased FCM eclosion success. FCM was sensitive to desiccation when the soils were dry and temperature limits of 15 °C and 32 °C had a strongly negative impact on eclosion success. Preferences for particular abiotic conditions were limited to only certain moisture conditions when interacting with soil texture class and a preference for pupating in soil when it is available. Limited preference was found for particular soil textures despite this having a strong influence on eclosion success, but individuals did appear to pupate in close proximity to one another. Viable direct habitat manipulation for FCM control could not be identified. These results and all of the abiotic variables measured have important implications for EPF and EPN application, survival and persistence in the soil in order to improve the ability of these biological control agents to control FCM. These are discussed in each chapter.

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Odorizzi, dos santos Luan alberto. "Contribution of marginal non-crop vegetation and semi-natural habitats to the regulation of insect pests populationsby their natural enemies." Thesis, Avignon, 2017. http://www.theses.fr/2017AVIG0693/document.

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L'expansion des zones agricoles a conduit à la perte de biodiversité due à la réduction des habitats naturels et semi-naturels dans les paysages agricoles. Avec l'augmentation de la production agricole dans le monde, des techniques écologiquement rationnelles sont de plus en plus discutées qui permettent une gestion durable des habitats environnants. Les effets de ces habitats sur la population des insectes nuisibles et de leurs ennemis naturels sont encore mal connus. L'objectif de cette thèse était de comprendre les effets des environnements naturels et semi-naturels sur la population des insectes nuisibles et des ennemis naturels dans les régions tropicales (Brésil) et tempérées (France). Au Brésil (chapitre II), on a évalué l'effet de la distance des fragments sur la population de fourmis prédatrices et omnivores dans la canne à sucre. Les résultats montrent que la richesse en espèces diminue avec la distance des fragments forestiers et que la prédominance des espèces Dorymyrmex bruneus et Pheidole oxyops augmente. Des espèces de fourmis colonisant les champs de canne à sucre ont également été trouvées dans des fragments forestiers, ce qui suggère que ces derniers habitats sont des refuges pour les espèces de fourmis prédatrices pendant les périodes de perturbation comme la récolte de la canne à sucre ou le travail du sol. Cela a été confirmé par des différences plus fortes dans les communautés de fourmis après la récolte de la canne à sucre (saison sèche) que quatre mois plus tard / (saison des pluies) quand l'absence de perturbation a permis la re-lonosiation par les fourmis. Il y avait aussi une différence dans la richesse des espèces de fourmis entre les différents types de fragments (vallées fluviales et plaines). En France, on a évalué l'effet des bandes de fleurs sauvages, de la végétation spontanée et des bandes d'herbe sur la communauté des ennemis naturels et la régulation du puceron de la pomme rosâtre Dysaphis plantaginaea (chapitre III). En ce qui concerne les principaux ennemis naturels, nos résultats ont montré une densité plus élevée de hoverflies par rapport à d'autres types de bande, mais aucune différence pour les coccinelles (coccinelidae). Cependant, aucune différence de densité naturelle de l'ennemi n'a été observée à l'intérieur des vergers. Le nombre de pucerons était plus élevé près des marges, ce qui suggère que la colonisation à partir des bandes marginales peut contrecarrer les effets régulateurs positifs des ennemis naturels. Les effets positifs de la végétation de la marge de bande sur la régulation des ravageurs de la pomme nécessitent un mouvement d'ennemis naturels dans le verger. Nous avons testé les mouvements des prédateurs généralistes en étiquetant les bandes de marge avec des protéines d'oeufs et nous avons vérifié si elles se nourrissaient d'insectes nuisibles en utilisant l'analyse de marqueurs génétiques des gènes de papillon (Cydia pomonella) à l'intérieur des prédateurs (chapitre IV). Les résultats ont montré que peu de personnes se déplaçaient des marges de champ dans le verger. Cependant, 25% des prédateurs capturés se nourrissaient de C. pomonella indiquant encore un haut niveau de régulation naturelle. En conclusion, le mouvement limité des prédateurs à partir des bandes de marges dans les vergers peut expliquer l'absence de différences entre les traitements de bandes dans la régulation des ravageurs du verger (pucerons). Les habitats naturels et semi-naturels peuvent contribuer à la lutte contre les ravageurs en marge des cultures, mais dans les vergers de pommiers cet effet a fortement diminué avec la distance
The expansion of agricultural areas has led to the loss of biodiversity due to the reduction of natural and semi-natural habitats in agricultural landscapes. With the increase of agricultural production in the world, environmentally sound techniques are increasingly discussed that allow a sustainable management of surrounding habitats. The effects of these habitats on the population of insect pests and their natural enemies are still poorly understood. The objective of this thesis was to understand the effects of natural and semi-natural environments on the population of insect pests and natural enemies in tropical (Brazil) and temperate (France) regions. In Brazil (Chapter II) the effect of the distance of fragments on the population of predatory and omnivorous ants in sugarcane was evaluated. The results showed that the species richness decrease with distance from forest fragments and that the dominance of the species Dorymyrmex bruneus and Pheidole oxyops increase. Ant species colonizing sugarcane fields were also found in forest fragments suggesting that the latter habitats are shelters for predatory ant species during periods of disturbance such as sugarcane harvest or soil tillage. This was confirmed by stronger differences in ant communities after sugarcane harvest (dry season) than four months later /(rainy season) when absence of disturbance allowed re-colonization by ants. There was also a difference in the richness of ant species between different fragment types (river valleys and plateaus). In France, the effect of wildflower strips, spontaneous vegetation and grass strips on the community of natural enemies and the regulation of the rosy apple aphid Dysaphis plantaginaea (Chapter III) were evaluated. Concerning major natural enemies, our results showed a higher density of hoverflies compared with other strip types but no difference for ladybirds (coccinelidae). No differences in natural enemy densities were observed inside orchards. Aphid number was higher close to the margins suggesting that colonization from margin strips may counteract positive regulatory effects of natural enemies. Positive effects of strip margin vegetation on regulation of apple pests require a movement of natural enemies into the orchard. We tested the movements of generalist predators by labelling margin strips with egg protein and we checked whether they fed on pest insects using genetic marker analysis of codling (Cydia pomonella) moth genes inside predators (chapter IV). The results showed that few individuals were moving from the field margins into the orchard. However, 25% of the captured predators fed on C. pomonella still indicating a high level of natural regulation. In conclusion, the limited movement of predators from margin strips into orchards may explain the absence of differences between strip treatments in orchard pest regulation (aphids). Natural and semi-natural habitats can contribute to pest control at the margins of crops, but in apple orchards this effect strongly decreased with distance

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36

Koller, Lorraine Marie. "Laboratory rearing, toxicity of cyromazine and the effect of temperature and manure moisture on Ophyra aenescens (Wiedemann) (Diptera: Muscidae)." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/71345.

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The effect of protein in adult and larval diets for Ophyra aenescens (Wiedemann) (Diptera: Muscidae ), a facultative predator of the house fly, Musca domestica L., was examined. A larval diet of coarse wheat bran, vermiculite and dried meat powder was found adequate for rearing O. aenescens larvae. Protein content was important for maximum larval emergence and for F1 adult longevity and fecundity. Adult diet of powdered milk, sugar and dried meat powder was sufficient for maintenance of adult O. aenescens flies. Protein was needed in adult diet for optimal fecundity. Cyromazine was toxic to O. aenescens at high levels (1.0 ppm), but at 0.75 ppm O. aenescens tolerated cyromazine better than a susceptible strain of house flies. At these cyromazine levels, mass release of O. aenescens into poultry houses is possible one to two days after cyromazine has been removed from the chicken feed. The effect of temperature and manure moisture on O. aenescens was studied. At temperatures of 18°C, emergence of Ophyra aenescens was significantly lower than at temperatures of 21 and 27°C. Predation by O. aenescens at 27°C on house fly larvae was significant at ratios of 3:1, 2:1 and 1:1 (house fly to O. aenescens). A constant manure moisture was important in the development of O. aenescens larvae and its ability to prey on house fly larvae. At constant levels of 50, 60, and 70% manure moisture, O. aenescens substantially reduced house fly larval numbers at ratios of 3:1, 2:1 and 1:1.
Master of Science

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Tobin, Michael. "The characterisation of a nucleopolyhedrovirus infecting the insect Trichoplusia ni." Thesis, Cape Peninsula University of Technology, 2019. http://hdl.handle.net/20.500.11838/2979.

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Thesis (MSc (Biomedical Sciences))--Cape Peninsula University of Technology, 2019
Background: Baculoviruses have great potential as alternatives to conventional chemical insecticides. The large scale adoption of such agents has however been hampered by the slow killing times exhibited by these bio-insecticides, limitation to single target insect and difficulty of large scale production of these preparations. Trichoplusia ni single nucleopolyhedrovirus (TnSNPV), initially identified in the Eastern Cape region of South Africa, has potential as a biocontrol agent as it possesses a higher speed of kill compared to other baculoviruses. Aims and methods: The main objective of this study was the identification, molecular characterisation and cloning of a structural core gene (polyhedrin) and three auxiliary genes, the inhibitor of apoptosis (iap2 and iap3) and the ecdysteroid UDP-glucosyltransferase (egt) genes, from TnSNPV in order to delineate its phylogenetic relationship to a Canadian isolate of the same virus and to other baculoviruses. In addition, the genes were expressed in an Escherichia coli (E. coli) based system as a prelude to genetic modification to increase the pesticidal property of the virus. Results: The genome size of the South African strain of TnSNPV was estimated at 160 kb and is significantly larger than the Canadian isolate of TnSNPV and may reflect genetic variation as the two strains have adapted to varying environmental conditions. Occlusion bodies of the South African strain of TnSNPV were visualised by Transmission Electron Microscopy and consisted of rod shaped single virions composed of a single enveloped nucleocapsid. Insect bioassays showed that the median lethal time (LT50) of the virus strain averaged 1.8 days which is significantly faster than other baculoviruses. The South African and Canadian strains of TnSNPV share nucleotide similarities greater than 95% for the genes analysed in this study, which indicates that they are closely related. From this analysis, the South African strain of TnSNPV identifies as a Group II NPV with the closest relatives being the Canadian strain of TnSNPV and ChchNPV. The topology of the tree for the polyhedrin protein was better resolved than that of the IAP2, IAP3 and EGT proteins and was comparable to the tree inferred from a concatenated data set consisting of complete polyhedrin/granulin, LEF8, and LEF9 proteins of 48 completely sequenced genomes. For the IAP2, IAP3 and EGT proteins, the separation of the lepidopteran and hymenopteran specific baculoviruses was not evident while the separation of Group I and II Alphabaculoviruses diverged from that observed from the baculovirus core gene polyhedrin as well as the tree inferred from complete polyhedrin/granulin, LEF8, and LEF9 proteins. Five distinct groups relating to IAP-1, 2, 3, 4 and 5 could be distinguished from the tree inferred from all IAP proteins from 48 fully sequenced baculoviruses. From this analysis, the IAP protein from the South African isolate of TnSNPV can be designated as an IAP3 due to sequence homology to other IAP3 proteins. Similarly, the IAP2 can be confirmed as an IAP2 protein as it clusters with other IAP2 proteins. RNA transcripts of the four genes were detected by RT-PCR at one hr after induction with Larabinose in BL21-A1 E. coli and persisted until four hrs post induction. Antisera directed against the C-terminal 6X His tag was able to detect the recombinant proteins at two hours after induction confirming the rapid rise in expression of the proteins which persisted at high levels until four hrs after induction. The discrepancy observed with the predicted molecular mass of the EGT protein and the migration on SDS-PAGE may be due to the absence of posttranslational modification in the E. coli expression system and the hydrophobic residues present in the N-terminal signal sequence. Conclusion: Sequence and phylogenetic analysis suggest that the two isolates of TnSNPV have been exposed to similar evolutionary pressures and evolved at similar rates and represent closely related but distinct variants of the same virus. The difference in genome size between the two strains is likely to reflect actual genetic differences as the strains have adapted to their local environments and hosts and the extent of the differences will only be apparent as more sequencing results become available. Phylogenetic analysis of the IAP and EGT proteins yields a tree that varies from the phylogenetic reconstruction observed for the polyhedrin gene as well as the concatenated data set consisting of complete polh/gran, LEF8, and LEF9 proteins and highlights the risks inherent in inferring phylogenetic relationships based on single gene sequences. The tree inferred from the concatenated data set of polh/gran, LEF8, and LEF9 proteins was a quick and reliable method of identification particularly, when whole genome data is unavailable and mirrors the accepted lineage of baculoviruses. Expression of the recombinant IAP2, IAP3, EGT and polyhedrin was confirmed by RT-PCR and immunoblot analysis and rose rapidly after induction and persisted at high levels. It is as yet unclear if the expressed proteins are functional particularly as post translation modifications are lacking in this system.

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38

Abonaem, Mokhtar [Verfasser], Johannes A. [Akademischer Betreuer] Jehle, and Jörg [Akademischer Betreuer] Simon. "Selection, Optimization and Technical Application of Entomopathogenic Nematodes for the Biological Control of Major Insect Pests on Tomato / Mokhtar Abonaem ; Johannes A. Jehle, Jörg Simon." Darmstadt : Universitäts- und Landesbibliothek, 2021. http://d-nb.info/123741492X/34.

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Santos, Laís da Conceição dos. "Uso de coentro e sorgo granífero em cultivo de tomate orgânico visando ao aumento de insetos predadores e polinizadores /." Jaboticabal, 2016. http://hdl.handle.net/11449/139504.

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Orientador: Francisco Jorge Cividanes
Coorientador: Terezinha Monteiro dos Santos Cividanes
Banca: Melissa Vieira Leite
Banca: Roberto Botelho Ferraz Branco
Banca: José Carlos Barbosa
Banca: Guilherme Duarte Rossi
Abstract: The objective of this study was to evaluate the effects of the strategy "push-pull" using sorghum plants (Sorghum bicolor L.) and coriander (Coriandrum sativum L.) on pests insect and predators and evaluate the abundance and species richness of Coleoptera, Hemiptera and bees in organic tomato. The experiment consisted of two treatments: a) polyculture; b) tomato monoculture. The polyculture was formed by tomato plants, Solanum lycopersicum L., coriander and sorghum. The evaluations were carried out fortnightly, from planting to end of crop cycle. In each plot the insects were sampled visually examining the whole plant, considering randomly 10 tomato plants, 10 plants of C. sativum and 10 plants of S. bicolor. The design was a randomized block with split plot in the time (Split-Plot) with 12 repetitions, the main treatments (plots) were represented by mono and tomato polyculture and secondary treatments (subplots) represented by the collection dates, having been evaluated eight dates in each crop cycle. The presence of sorghum and coriander did not significantly reduce the population density of Tuta absoluta (Meirick) (Lepidoptera: Gelechiidae), Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), Caliothrips phaseoli Hood (Thysanoptera: Thripidae) and Aphis gossypii Glover (Hemiptera: Aphididade) in tomato in greenhouse. The tomato-coriander-sorghum polyculture favors the occurrence of insect predators, especially after flowering coriander. Coriander provides greater diversit... (Complete abstract click electronic access below)
Resumo: O objetivo do presente estudo foi avaliar os efeitos da estratégia "pushpull" utilizando plantas de sorgo (Sorghum bicolor L.) e coentro (Coriandrum sativum L.) sobre insetos-praga e predadores e avaliar a abundância e riqueza de espécies de Coleoptera, Hemiptera e abelhas, em tomateiro orgânico cultivado em casa-devegetação. O experimento foi composto de dois tratamentos: a) policultivo e b) monocultivo de tomateiro. O policulivo compreendeu plantas de tomate, Solanum lycopersicum L., de coentro e sorgo. As avaliações foram quinzenais e realizadas desde o plantio até o fim do ciclo da cultura. Em cada parcela os insetos foram amostrados visualmente examinando-se toda a planta, considerando-se aleatoriamente 10 plantas de tomateiro, 10 plantas de C. sativum e 10 plantas de S. bicolor. O delineamento utilizado foi o de blocos casualizados com parcelas subdivididas no tempo (Split-Plot), com 12 repetições, sendo os tratamentos principais (parcelas) representados pelo mono e policultivo de tomateiro e os tratamentos secundários (subparcelas) representados pelas datas de coleta, sendo oito datas de coleta para cada safra. A presença de sorgo e coentro não reduz significativamente a densidade populacional de Tuta absoluta (Meirick) (Lepidoptera: Gelechiidae), Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), Caliothrips phaseoli Hood (Thysanoptera: Thripidae) e Aphis gossypii Glover (Hemiptera: Aphididade) no tomateiro em casa-de-vegetação. O policultivo tomateiro-coentrosorgo ... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor

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Silva, Alexandre Cândido da [UNESP]. "Potencial de nematóides entomopatogênicos para o controle da mosca-do-mediterrâneo Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) e do gorgulho-da¬goiaba Conotrachelus psidii (Marshal) (Coleoptera: Curculionidae)." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/97220.

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Made available in DSpace on 2014-06-11T19:28:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-26Bitstream added on 2014-06-13T19:58:12Z : No. of bitstreams: 1 silva_ac_me_botfca.pdf: 1497139 bytes, checksum: 1ec5c66837f996b2bf5ed59ec09974f8 (MD5)
Fundação de Apoio à Pesquisa Agrícola (FUNDAG)
Dentre os insetos pragas mais freqüentes e limitantes à produção de frutas, incluem-se a mosca-do-mediterrâneo, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), e o gorgulho-da-goiaba, Conotrachelus psidii (Marshal) (Coleoptera: Curculionidae). As larvas desses insetos se alimentam da polpa das frutas, sendo que no final dessa fase, os insetos descem para o solo onde se enterram e atravessam a fase de pupa. O objetivo do trabalho foi avaliar a virulência de 7 nematóides dos gêneros Steinernema e Heterorhabditis contra a mosca-do-mediterrâneo, e o potencial de Heterorhabditis indica Poinar, Karunakar & David 1992 no controle desse inseto e do gorgulho-da-goiaba. Foram realizados cinco experimentos, sendo um experimento em laboratório, três em casa de vegetação e um em campo. De acordo com os resultados, a mosca-do-mediterrâneo é suscetível aos nematóides quando exposta no estágio de pré-pupa e fase de pupa com 1 dia de desenvolvimento; O nematóide H. indica IBCB n5 mostrou-se como o mais virulento contra C. capitata. No teste de campo procurando avaliar H. indica IBCB n5 contra C. capitata e contra C. psidii, todos os tratamentos diferenciaram significativamente da testemunha. O nematóide apresentou-se bem mais eficiente contra a mosca-do¬mediterrâneo, com mortalidade do inseto de 66% e 93% para as dosagens de 1 e 10 JI/cm², respectivamente, do que contra o gorgulho-da-goiaba, com mortalidade de 33% e 50%, respectivamente, tendo todos esses tratamentos diferidos significativamente da testemunha
The fruit fly, Ceratitis capitata, and the guava weevil, Conotrachelus psidii, are among the most frequent and injurious pest of fruit crops. The insects larva feed on the fruit pulp and, at the end of this phase, the insects reach the soil where they spent their pupa phase. This research aimed to evaluate the virulence of 7 strains of entomopathogenic nematodes against the fruit fly in laboratory and green house conditions, and the efficiency of Heterorhabditis indica IBCB n5 against this insect and the guava weevil on field conditions. Five trials were done, being one trial done in laboratory, 3 in green house, and one at field condition. According to the results, the fruit fly is susceptible to the nematodes when exposed at the phases of pre-pupa and one day aged pupa. H. indica IBCB n5 was the most virulent nematode against C. capitata. At the field trial aiming to evaluate the efficiency of H. indica IBCB n5 against C. capitata and C. psidii, all the treatments with the nematode differed significantly from the control. H. indica IBCB n5 showed being much more virulent to the fruit fly, with insect mortality ranging from 66% to 93% at the dosages from 1 to 10 IJ/cm2, respective than to the guava weevil, with mortality ranging from 33 to 50%, respectively

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Dantzger, Miriam 1981. "Inibidor de proteinase do tipo Bowman-Birk isolado de sementes de Clitoria fairchildiana (Fabaceae) : caracterização e atividade biológica sobre Anagasta kuehniella e Corcyra cephalonica." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314532.

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Orientador: Maria Lígia Rodrigues Macedo
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-26T06:33:25Z (GMT). No. of bitstreams: 1 Dantzger_Miriam_D.pdf: 2351280 bytes, checksum: b2da4015dedd7611bbce146ad9143d6f (MD5) Previous issue date: 2014
Resumo: Os inibidores de proteinases extraídos de plantas têm se mostrado promissores como um método alternativo no combate aos insetos-pragas. Neste estudo, um inibidor de peptidase foi isolado de sementes de Clitoria fairchildiana (Papilionoideae), denominado CFPI, caracterizado funcional e estruturalmente e sua atividade inseticida foi avaliada. CFPI foi purificado por exclusão molecular, seguido por coluna de interação hidrofóbica e apresentou um pico majoritário com atividade inibitória após ter sido submetido à filtração com alta resolução. Estudos cinéticos realizados com CFPI purificado mostraram uma atividade inibitória do tipo competitiva contra tripsina e quimotripsina bovinas, com uma estequiometria de inibição de 1:1 para ambas as enzimas. A constante de inibição de CFPI contra tripsina e quimotripsina bovinas foram 3,3 x 10-10 e 1,5 x 10-10 M, respectivamente, revelando uma forte capacidade de ligação. Eletroforese em SDS-Page mostrou que CFPI possui uma única cadeia polipeptídica, com uma massa molecular aparente de 15 kDa, sob condições não redutoras. Entretanto, o inibidor apresentou uma massa acurada de 7973 Daltons determinada por MALDI-TOF, sugerindo que CFPI forme dímeros em solução. Essa característica, aliada à estequiometria de inibição para tripsina e quimotripsina, à constante de inibição (Ki) para ambas as enzimas e ao sequenciamento e alinhamento N-terminal, permitiram classificar CFPI como membro da família Bowman-Birk de inibidores. O inibidor manteve-se estável ao aquecimento progressivo por 30 min a cada temperatura, variando de 37 até 100 ?C e a análise de dicroísmo não mostrou mudanças no espectro a 207 nm após aquecimento à 90 ?C e subsequente resfriamento. Além disso, CFPI mostrou atividade sobre uma ampla faixa de pH (2-10). Em contraste, a redução de CFPI com DTT resultou em perda de atividade inibitória contra tripsina e quimotripsina. CFPI exibiu atividade inibitória considerável contra enzimas tripsinas de Anagasta kuehniella (76%), Diatraea saccharalis (59%) e Heliothis virescens (49%). Suas propriedades inseticidas foram confirmadas a partir do impacto negativo causado no crescimento de A. kuehniella e C. cephalonica. O inibidor exerceu efeito antinutricional sobre A. kuehniella tanto na geração F0 como em F1
Abstract: Proteinase inhibitors isolated from plants have shown a promising alternative method against insect pests. In this study, a proteinase inhibitor was isolated from Clitoria fairchildiana seeds (CFPI). CFPI was functional and structurally characterized and its insecticidal activity was evaluated. CFPI was purified by molecular exclusion, following by hydrophobic interaction column and showed a majoritarian peak with inhibitory activity after high resolution filtration gel column. Kinetic studies of the purified inhibitor showed a competitive¿type inhibitory activity against bovine trypsin and chymotrypsin, with an inhibition stoichiometry of 1:1 for both enzymes. The inhibition constants against trypsin and chymotrypsin were 3.3 ×10?10 and 1.5 × 10?10 M, respectively, displaying a tight binding property. SDS¿PAGE showed that CFPI has a single polypeptide chain with an apparent molecular mass of 15 kDa under non¿reducing conditions. However, MALDI¿TOF analysis demonstrated a molecular mass of 7.973 Da, suggesting that CFPI forms dimers in solution. This feature, combined with the stoichiometry of inhibition for trypsin and chymotrypsin, the inhibition constant (Ki) for both enzymes and the N-terminal sequencing, allowed classifying CFPI as a member of Bowman-Birk family inhibitors. CFPI remained stable to progressive heating for 30 min to each temperature range of 37 up to 100 °C and CD analysis exhibited no changes in spectra at 207 nm after heating at 90 °C and subsequent cooling. Moreover, CFPI was active over a wide pH range (2¿10). In contrast, reduction with DTT resulted in a loss of inhibitory activity against trypsin and chymotrypsin. CFPI also exhibited remarkable inhibitory activity against larval midgut trypsin enzymes from Anagasta kuehniella (76%), Diatraea saccharalis (59%) and Heliothis virescens (49%). Its insecticidal properties were further analysed by bioassays and confirmed by negative impact on growth of A. kuehniella and C. cephalonica. The inhibitor exhibited antinutritional effect on A. kuehniella in the F0 and F1 generations
Doutorado
Bioquimica
Doutora em Biologia Funcional e Molecular

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42

Alfaro, Lemus Ana Lilia. "Factors influencing the control of citrophilous mealybug Pseudococcus calceolarie (Maskell) by Coccophagus gurneyi Compere in the Riverland of South Australia." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09IM/09iml562.pdf.

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Includes bibliographical references (leaves 102-114) The highly successful biological control of the citrophilous mealybug Pseudococcus calceolarie (Maskell) (CM) by the parasitic wasp Coccophagus gurneyi Compere in several countries led to the release of this parasitoid in the Riverland of South Australia as part of an integrated pest management program. However CM has not been successfully controlled in this region. The results of this study may help to explain the lack of effective biological control of CM in Riverland citrus.

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Hepburn, Colleen. "Composition and phenology of insect pests of Capsicum (Solanaceae) cultivated in the Makana District, Eastern Cape Province, South Africa." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1005339.

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Capsicum baccatum var. pendulum was first grown in the Makana District in 2005. Extremely little was known about best practices for cultivation or the insects and diseases associated with the crop in this area. The study was conducted during the second year of production, November 2005 and November 2006, in an attempt to identify the composition and phenology of insects occurring on C. baccatum. In the more rural parts of the Eastern Cape, and more particularly in Grahamstown, there are very few industries. With the advent of this new agricultural venture, a processing factory has been opened in Grahamstown creating more than 600 seasonal jobs in the factory and 1000 seasonal jobs on farms for local people. This business enterprise has not only brought about the creation of jobs, but also training and skills development and empowerment, generating much-needed income in this area. An extensive literature review yielded limited information on insect pests associated with Capsicum. Data from a pilot sampling trial undertaken were statistically analyzed to establish the number of plants to be scouted per site and the most effective scouting techniques to use. Based on the data available and insects collected during the pilot sampling trial, a surveillance programme was designed. Five different types of monitoring traps were placed in each of the eight study sites. Collection of trap catches and scouting of fifteen individual plants per site was undertaken on a weekly basis over the 52-week study period. The most commonly occurring potential insect pests were African Bollworm Helicoverpa armigera (Hübner), False Codling Moth Thaumatotibia leucotreta (= Cryptophlebia leucotreta) (Meyrick), Mediterranean Fruit Fly Ceratitis capitata (Wiedemann) and several species of thrips. Population densities of these pests and their phenology on Capsicum were determined. Statistical analyses established the efficacy of the monitoring traps for each pest, tested for differences among and between study sites, calculated an estimate of the number of pods damaged and a measure of plant damage.The results show that the majority of damage caused to the Capsicum baccatum cropping system was due to Mediterranean Fruit Fly populations. It was established that, although African Bollworm and False Codling Moth were present during the study period, their numbers were negligible and only nominal damage was caused by these pests. Damage caused by thrips species was apparent but not quantifiable. Intervention strategies using an Integrated Pest Management approach, are discussed.

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Chambers, Craig Brian. "Production of Cydia pomonella granulovirus (CpGV) in a heteralogous host, Thaumatotibia Leucotreta (Meyrick) (False codling moth)." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1017906.

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Cydia pomonella (Linnaeus) (Family: Tortricidae), the codling moth, is considered one of the most significant pests of apples and pears worldwide, causing up to 80% crop loss in orchards if no control measures are applied. Cydia pomonella is oligophagous feeding on a number of alternate hosts including quince, walnuts, apricots, peaches, plums and nectarines. Historically the control of this pest has been achieved with the use of various chemical control strategies which have maintained pest levels below the economic threshold at a relatively low cost to the grower. However, there are serious concerns surrounding the use of chemical insecticides including the development of resistance in insect populations, the banning of various insecticides, regulations for lowering of the maximum residue level and employee and consumer safety. For this reason, alternate measures of control are slowly being adopted by growers such as mating disruption, cultural methods and the use of baculovirus biopesticides as part of integrated pest management programmes. The reluctance of growers to accept baculovirus or other biological control products in the past has been due to questionable product quality and inconsistencies in their field performance. Moreover, the development and application of biological control products is more costly than the use of chemical alternatives. Baculoviruses are arthropod specific viruses that are highly virulent to a number of lepidopteran species. Due to the virulence and host specificity of baculoviruses, Cydia pomonella granulovirus has been extensively and successfully used as part of integrated pest management systems for the control of C. pomonella in Europe and around the world, including South Africa. Commercial formulations have been typically based on the Mexican strain of CpGV. However due to long-term multiple applications of CpGV and the reliance on CpGV in organic farming practices in Europe, resistance to the CpGV-M strain has developed in a number of field populations of C. pomonella. This study aimed to identify and characterize novel isolates of CpGV in South Africa and compare their virulence with the commercial standard CpGV-M. Secondly, since C. pomonella is difficult to culture on a large scale, an alternate method of CpGV production was investigated in order to determine if CpGV could be produced more efficiently and at a reduced cost without negatively impacting the quality of the product. Several isolates of CpGV were recovered either from field collected larvae or from a laboratory-reared C. pomonella colony. Characterisation of DNA profiles using a variety of restriction enzymes revealed that only a single isolate, CpGV-SA, was genetically different from the Mexican strain of the virus used in the commercially available CpGV based products in South Africa. In dose-response bioassays using CpGV-SA, LC₅₀ and LC₉₀ values for neonate C. pomonella larvae were 3.18 x 10³ OBs/ml and 7.33 x 10⁴ respectively. A comparison of these values with those of CpGV-M indicated no significant difference in the virulence of the two isolates under laboratory conditions. This is a first report of a genetically distinct CpGV isolate in South Africa. The biological activity and novelty of CpGV-SA makes this isolate a potentially important tool for CpGV resistance management in South Africa. In order to justify production of CpGV in an alternative host, studies on the comparative biological performance of C. pomonella and T. leucotreta based on oviposition, time to hatch, larval developmental times and rearing efficiency as well as production costs were performed. Thaumatotibia leucotreta was found to be more fecund and to have significantly shorter egg and larval developmental times. In addition, larval production per unit of artificial diet was significantly higher than for C. pomonella. This resulted in T. leucotreta being more cost effective to produce with implications for reduced insectary space, sanitation practices as well as the labour component of production. Virus yield data generated by inoculation both C. pomonella and T. leucotreta with nine concentrations of CpGV resulted in comparable virus yields, justifying the continuation of the research into production of CpGV in T. leucotreta. It was important to determine the LC and LT values required for mass production of CpGV in late instar T. leucotreta larvae. Dose- and time-response bioassays with CpGV-M were conducted on artificial diet to determine these values. Fourth instar LC₅₀ and LC₉₀ values were 5.96 x 10³ OBs/ml and 1.64 x 10⁵ OBs/ml respectively. LT50 and LT90 values were 81.10 hours and 88.58 hours respectively. Fifth instar LC₅₀ and LC₉₀ values were 6.88 x 10⁴ OBs/ml and 9.78 x 10⁶ OBs/ml respectively. LT₅₀ and LT₉₀ values were 111.56 hours and 137.57 hours respectively. Virus produced in fourth instar T. leucotreta larvae was bioassayed against C. pomonella neonate larvae and compared to CpGV-M to establish if production in the heterologous host negatively affected the virulence of the isolate. No significant difference in virulence was observed between virus produced in T. leucotreta and that produced in C. pomonella. The data generated in the bioassays was used in CpGV mass production trials to evaluate production. All production methods tested produced acceptable virus yields. To examine the quality of the virus product, genomic DNA was extracted from larval cadavers and subjected to REN analysis with HindIII. The resulting DNA profiles indicated that the virus product was contaminated with the homologous virus, CrleGV. Based on the above results, the use of T. leucotreta as an alternate host for the in vivo production of CpGV on a commercial basis is not at this stage viable and requires further investigation before this production methodology can be reliable used to produce CpGV. However, this study has shown that CpGV can be produced in a homologous host, T. leucotreta and significant strides have been made towards developing a set of quality control standards that are essential for further development of successful production methodology. Finally a novel isolate of CpGV has been identified with comparable virulence to the CpGV-M. This is an important finding as it has broad reaching implications for resistance management of CpGV products in South Africa.

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45

Östman, Örjan. "Landscape and farm management influence generalist predators : effects on condition, abundance, and biological control /." Uppsala : Swedish University of Agricultural Sciences, 2002. http://diss-epsilon.slu.se/archive/00000207/.

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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2002.
Thesis documentation sheet inserted. Appendix reprints five published papers and manuscripts, three co-authored with others. Includes bibliographical references. Also available electronically via World Wide Web in PDF format; online version lacks appendix.

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46

Silva, Alexandre Cândido da 1976. "Potencial de nematóides entomopatogênicos para o controle da mosca-do-mediterrâneo Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) e do gorgulho-da¬goiaba Conotrachelus psidii (Marshal) (Coleoptera: Curculionidae)." Botucatu : [s.n.], 2009. http://hdl.handle.net/11449/97220.

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Orientador: Antonio Batista Filho
Banca: Silvia Renata Siciliano Wilcken
Banca: Luis Garrigós Leite
Resumo: Dentre os insetos pragas mais freqüentes e limitantes à produção de frutas, incluem-se a mosca-do-mediterrâneo, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), e o gorgulho-da-goiaba, Conotrachelus psidii (Marshal) (Coleoptera: Curculionidae). As larvas desses insetos se alimentam da polpa das frutas, sendo que no final dessa fase, os insetos descem para o solo onde se enterram e atravessam a fase de pupa. O objetivo do trabalho foi avaliar a virulência de 7 nematóides dos gêneros Steinernema e Heterorhabditis contra a mosca-do-mediterrâneo, e o potencial de Heterorhabditis indica Poinar, Karunakar & David 1992 no controle desse inseto e do gorgulho-da-goiaba. Foram realizados cinco experimentos, sendo um experimento em laboratório, três em casa de vegetação e um em campo. De acordo com os resultados, a mosca-do-mediterrâneo é suscetível aos nematóides quando exposta no estágio de pré-pupa e fase de pupa com 1 dia de desenvolvimento; O nematóide H. indica IBCB n5 mostrou-se como o mais virulento contra C. capitata. No teste de campo procurando avaliar H. indica IBCB n5 contra C. capitata e contra C. psidii, todos os tratamentos diferenciaram significativamente da testemunha. O nematóide apresentou-se bem mais eficiente contra a mosca-do¬mediterrâneo, com mortalidade do inseto de 66% e 93% para as dosagens de 1 e 10 JI/cm², respectivamente, do que contra o gorgulho-da-goiaba, com mortalidade de 33% e 50%, respectivamente, tendo todos esses tratamentos diferidos significativamente da testemunha
Abstract: The fruit fly, Ceratitis capitata, and the guava weevil, Conotrachelus psidii, are among the most frequent and injurious pest of fruit crops. The insects larva feed on the fruit pulp and, at the end of this phase, the insects reach the soil where they spent their pupa phase. This research aimed to evaluate the virulence of 7 strains of entomopathogenic nematodes against the fruit fly in laboratory and green house conditions, and the efficiency of Heterorhabditis indica IBCB n5 against this insect and the guava weevil on field conditions. Five trials were done, being one trial done in laboratory, 3 in green house, and one at field condition. According to the results, the fruit fly is susceptible to the nematodes when exposed at the phases of pre-pupa and one day aged pupa. H. indica IBCB n5 was the most virulent nematode against C. capitata. At the field trial aiming to evaluate the efficiency of H. indica IBCB n5 against C. capitata and C. psidii, all the treatments with the nematode differed significantly from the control. H. indica IBCB n5 showed being much more virulent to the fruit fly, with insect mortality ranging from 66% to 93% at the dosages from 1 to 10 IJ/cm2, respective than to the guava weevil, with mortality ranging from 33 to 50%, respectively
Mestre

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47

Tourle, Robyn. "Effects of ant predation on the efficacy of biological control agents Hypena Laceratalis Walker (Lepidoptera : noctuirdae) ; Falconia intermedia Distant (Hemiptera : Miridae and Teleonemia scrupulosa Stål (Hemiptera: Tingidae) on Lantana Camara (Verbenaceae) in South Africa." Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1005362.

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Lantana camara L. (Verbenaceae) remains a highly invasive and ecologically damaging weed in South Africa, despite some 50 years of biological control efforts. Lack of success has been ascribed to varietal differences, climate and predation of agents but these have not been tested. In this study, the effects of ant predation were tested on populations of three biological control agents for L. camara. Colonies of two species, Crematogaster sp. 1 and 2 were investigated. Crematogaster sp. 1 colonies were offered no choice between immature stages of the agents Hypena laceratalis Walker (Lepidoptera: Noctuidae), Falconia intermedia Distant (Hemiptera: Miridae) or Teleonemia scrupulosa Stål (Hemiptera: Tingidae) on lantana shoots. Density-dependent predation on F. intermedia and T. scrupulosa nymphs on lantana shoots was tested using Crematogaster sp. 2 colonies. In choice experiments Crematogaster sp. 2 colonies were offered F. intermedia or T. scrupulosa nymphs on potted lantana plants. Preliminary food trials confirmed that colonies foraged for protein, thereby validating results of no-choice experiments. Crematogaster sp.1 foragers removed 50% of F. intermedia nymphs, followed by 45% of H. laceratalis larvae and only 9% of T. scrupulosa nymphs. Foragers recruited most actively to H. laceratalis larvae and significantly more H. laceratalis biomass was removed than either F. intermedia or T. scrupulosa. A trade-off existed in prey size selection because larger larvae provided considerably more biomass but required forager cooperation and a longer time to subdue than did smaller prey. This increases both forager energy expense and mortality risk by other predators. This study showed that all Crematogaster sp. 1 colonies removed small (≤10mm) H. laceratalis larvae more frequently than larvae larger than 10mm. Thus, of these biological control agents, predators probably prefer small H. laceratalis larvae. Significantly more F. intermedia than T. scrupulosa nymphs were removed by Crematogaster sp. 1, while Crematogaster sp. 2 colonies removed comparable numbers of both agent species. Falconia intermedia nymphs' fast movement triggered a predatory response by these ant species. In contrast, the relatively immobile behaviour of T. scrupulosa nymphs was identified as a highly effective predator avoidance strategy. Since T. scrupulosa nymphs are unable to escape predators by moving, they appear to depend on the presence of alternative prey attracting predator attention. At high agent and/or forager density, T. scrupulosa nymphs attempted escape, but foragers identified them as prey once they moved and caught them. Predation on F. intermedia was also density dependent in that at high nymph and/or forager densities, escape routes were congested and nymphs were more easily caught. Survival of F. intermedia and T. scrupulosa nymphs in particular was low on ant-accessed shrubs in choice experiments and high on ant-excluded shrubs. It is likely that ants significantly depress F. intermedia populations in the field since besides predation, ant foragers probably interrupt F. intermedia feeding and ovipositioning. The combination of parasitism and predation on early instar larvae may explain why H. laceratalis occurs across lantana's range in South Africa but populations remain low. It is unlikely that T. scrupulosa nymphs are habitually preyed on by ant species unless they attract attention by being mobile. Although biological control of L. camara is influenced by climate and physiological defence mechanisms, this study has shown that predation by two ant species severely impacts leaf-feeding agents for L. camara. Thus, it is recommended that future selection of additional agents to control lantana should exclude leaf-feeding .

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Stenekamp, Daleen. "Optimization of a mass-rearing system to produce codling moth, Cydia pomonella, for a Sterile Insect Release programme in South Africa." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6658.

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Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: Codling moth, Cydia pomonella, is a worldwide pest and of major economic importance to the South African pome fruit industry. Sterile insect release is applied as a component of area-wide integrated pest management and includes the mass-rearing, sterilization and the release of the sterile insects. For sterile insect release, the improvements of rearing methods in terms of the quality of the diet ingredients and the economical aspect of the rearing method are examined. The effect of genetically modified maize meal, containing the Bacillus thuringiensis gene, in an artificial medium for codling moth rearing, is determined. The use of even a small amount of Bacillus thuringiensis resulted in larval mortality and prolonged development. These results are detrimental to a mass-rearing facility and must be considered by any rearing facility that uses genetically modified maize meal if the insect is sensitive to the gene. An alternative to maize meal in the artificial medium was tested and whole wheat flour was considered to be a suitable replacement. Agar agar is an expensive gelling agent used in the artificial medium. An alternative for agar agar (Kelcogel, Elastigel and carrageenen) is tested and the biological effect on codling moth is determined. Factors such as mortality, pupal and moth weight, longevity, fecundity and development time were used as quality parameters. Results showed that Elastigel was a suitable replacement for agar agar, with bigger pupae and moths, higher fecundity and increased longevity. The economical advantage of the replacement is a 40.91% reduction of the diet cost. The other gelling agents tested also gave acceptable results and can be considered if shortages of agar agar or Elastigel occur. A new method of mass-rearing codling moth larvae in a closed rearing system using large trays placed in a ventilated box is designed. This method is more cost and space effective as a smaller area is needed to rear a large number of moths. The risk of diet contamination is less because of the closed environment and more economical and effective air handling. This is the first report of its kind to describe the mass-rearing of codling moth in a closed environment and the risks involved in using genetically modified maize meal in an artificial diet for the codling moth. These results should be incorporated into existing mass-rearing facilities or taking into consideration when designing new mass-rearing facilities.
AFRIKAANSE OPSOMMING: Die kodlingmot, Cydia pomonella, is van ekonomiese belang vir die Suid-Afrikaanse kernvrugte bedryf. Die steriele insek tegniek word gebruik as ‘n komponent in area-wye geïntegreerde plaagbeheer en sluit in die massa-aanteel, sterilisering en vrylaat van steriele insekte. Vir die steriele insek tegniek is die verbetering van die massa-aanteel van die kodlingmot in terme van kwaliteit van die dieet en die ekonomiese aspek van die aanteel metode ondersoek. Die effek van genetiese gemanipuleerde mieliemeel wat die Bacillus thuringiensis geen bevat, in ‘n kunsmatige voedselmedium vir die aanteel van kodlingmot, is bepaal. Daar is gevind dat die gebruik van selfs ‘n klein persentasie Bacillus thuringiensis in die mieliemeel, mortaliteit en ‘n verlengde lewenssiklus in kodlingmot veroorsaak. Die gevolge is nadelig vir ‘n massa-aanteel fasiliteit en behoort in ag geneem te word vir enige insek wat op ‘n kunsmatige medium, wat mieliemeel bevat, geteel word, mits die insek sensitief is vir Bacillus thuringiensis. ‘n Alternatiewe bestanddeel vir mieliemeel, volkoringmeel, word aanbeveel. Agar agar is ‘n duur verdikkingsagent wat in kunsmatige mediums gebruik word. ‘n Alternatief vir agar agar (Kelcogel, Elastigel en carrageenen) is getoets en die biologiese effek op die kodlingmot is bepaal. Faktore soos mortaliteit, papie en mot gewig, langlewendheid, vrugbaarheid en lengte van lewenssiklus was gebruik as kwaliteit parameters. Resultate het getoon dat Elastigel ‘n geskikte plaasvevanger is van agar agar, met groter papies en motte, groter vrugbaarheid en langlewendheid. Die ekonomiese gevolg van die plaasvervanger, is ‘n vermindering van 40.91% van die dieetkoste. Die ander verdikkingagente wat is getoets is, het aanvaarbare resultate gelewer wat noodsaaklik is indien daar ‘n tekort van Elastigel of agar agar ontwikkel. ‘n Nuwe metode van massa-aanteel van kodlingmot larwes is bepaal. Die metode behels ‘n geslote sisteem, waar groter aanteel bakke in ‘n geslote, geventileerde boks geplaas word. Die metode is koste en spasie effektief en ‘n kleiner area word benodig om ‘n groter aantal motte te lewer. Die risiko van kontaminasie van die dieet word verminder as gevolg van die geslote sisteem wat gebruik word en meer ekonomiese en effektiewe lugversorging word gebruik. Hierdie is die eerste verslag van sy soort wat die massa-aanteel van kodlingmot in ‘n geslote sisteem beskryf en wat die risiko aandui van geneties gemanipuleerde mieliemeel in ‘n kunsmatige medium vir die kodlingmot. Hierdie resultate behoort in ag geneem te word vir reeds bestaande massa-aanteel fasiliteite of met die ontwerp van nuwe massa-aanteel fasiliteite.

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Crowe, Michael, and University of Lethbridge Faculty of Arts and Science. "Ecological interactions between insect herbivores and their host plant in a weed biocontrol system." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2003, 2003. http://hdl.handle.net/10133/637.

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The role of interspecific competition as a regulating force in natural populations has been controversial, especially for phytophagous insect communities. A series of manipulative experiments using enclosure cages were conducted to evaluate the role of interspecific competition between a weevil and a fly, two seed feeding agents released against spotted knapweed in North America. The fly, an inferior biological control agent, was the superior competitor. Consequences of the antagonistic interaction included reduced seed destruction compared to if just the weevil was released on its own. The role of plant phenology on insect herbivore density was also assessed. The implications of phenologyinduced variation in insect density were evaluated with respect to competition between the fly and the weevil and were found to be important. Hypotheses of four plantmediated mechanisms of interspecific competition were also tested. Results support resource preemption as a competitive mechanism.
vii, 97 leaves ; 29 cm

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Yamoah, Emmanuel. "A model system using insects to vector Fusarium tumidum for biological control of gorse (Ulex europaeus)." Phd thesis, Lincoln University. Bio-Protection and Ecology Division, 2007. http://theses.lincoln.ac.nz/public/adt-NZLIU20080131.114607/.

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The overall objective of this study was to test the hypothesis that insects can vector F. tumidum conidia to infect gorse plants with the aim of developing an alternative approach to mycoherbicide delivery to control weeds. Four potential insect species (Apion ulicis, Cydia ulicetana, Epiphyas postvittana and Sericothrips staphylinus) were assessed for their ability to vector F. tumidum conidia. To achieve this, the external microflora (bacteria and fungi) and the size and location of fungal spores on the cuticle of these insect species were determined. In addition, the ability of the insects to pick up and deposit F. tumidum conidia on agar was studied. Based on the results from these experiments, E. postvittana was selected for more detailed experiments to determine transmission of F. tumidum to infect potted gorse plants. The factors promoting pathogenicity of F. tumidum against gorse and the pathogen loading required to infect and kill the weed were also determined. The external microflora of the four insect species were recovered by washing and plating techniques and identified by morphology and polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and sequencing of internally transcribed spacer (ITS) and 16S rDNA. A culture-independent technique (direct PCR) was also used to assess fungal diversity by direct amplification of ITS sequences from the washings of the insects. All insect species carried Alternaria, Cladosporium, Nectria, Penicillium, Phoma, Pseudozyma spp. and entomopathogens. Ninety four per cent of the 178 cloned amplicons had ITS sequences similarity to Nectria mauritiicola. E. postvittana carried the largest fungal spores (mean surface area of 125.9 ìm2) and the most fungal CFU/insect. About 70% of the fungi isolated from the insects were also present on the host plant (gorse) and the understorey grass. The mean size of fungal spores recovered from the insect species correlated strongly with their body length (R² = 85%). Methylobacterium aquaticum and Pseudomonas lutea were common on all four insect species. Pseudomonas fluorescens was the most abundant bacterial species. In the pathogenicity trials, the effectiveness of F. tumidum in reducing root and shoot biomass of 16 and 8 wk old gorse plants was significantly increased with wounding of the plants. Older plants (32 wk old) which were wounded and inoculated were significantly shorter, more infected and developed more tip dieback (80%) than plants which were not wounded (32%). This indicates that damage caused by phytophagous insect species present on gorse through feeding and oviposition may enhance infection by F. tumidum. Wounding may release nutrients (e.g. Mg and Zn) essential for conidia germination and germ tube elongation and also provide easier access for germ tube penetration. Conidial germination and germ tube length were increased by 50 and 877%, respectively when incubated in 0.2% of gorse extract solution for 24 h compared with incubation in water. Inoculum suspensions amended with 0.2% of gorse extract caused more infection and significantly reduced biomass production of 24 wk old gorse plants than suspensions without gorse extract. A minimum number of about 900 viable conidia/infection site of F. tumidum were required to infect gorse leaves. However, incorporation of amendments (which can injure the leaf cuticle) or provision of nutrients (i.e. gorse extract or glucose) in the formulation might decrease the number of conidia required for lesion formation. Scanning electron micrographs showed that germ tube penetration of gorse tissue was limited to open stomata which partly explain the large number of conidia required for infection. The flowers and leaves were more susceptible to F. tumidum infection than the spines, stems and pods. An experiment to determine the number of infection sites required to cause plant mortality showed that the entire plant needs to be inoculated in order for the pathogen to kill 10 wk old plants as F. tumidum is a non systemic pathogen. The number of infection sites correlated strongly with disease severity (R² = 99.3%). At least 50% of the plant was required to be inoculated to cause a significant reduction in shoot dry weight. F. tumidum, applied as soil inoculant using inoculated wheat grains in three separate experiments, significantly suppressed gorse seedling emergence and biomass production. In experiments to determine the loading capacity of the insect species, E. postvittana, the largest insect species studied, carried significantly more (68) and deposited significantly more (29) F. tumidum conidia than the other species. Each E. postvittana, loaded with 5,000 conidia of F. tumidum, transmitted approximately 310 conidia onto gorse plants but this did not cause any infection or affect plant growth as determined by shoot fresh weight and shoot height. E. postvittana on its own did not cause any significant damage to gorse and did not enhance F. tumidum infection. It also failed to spread the pathogen from infected plants to the healthy ones. There was no evidence of synergism between the two agents and damage caused by the combination of both E. postvittana and F. tumidum was equivalent to that caused by F. tumidum alone. This study has shown that E. postvittana has the greatest capacity to vector F. tumidum since it naturally carried the largest and the most fungal spores (429 CFU/insect). Moreover, it naturally carried Fusarium spp. such as F. lateritium, F. tricinctum and Gibberella pulicaris (anamorph Fusarium sambucinum) and was capable of carrying and depositing most F. tumidum conidia on agar. Coupled with the availability of pheromone for attracting the male insects, E. postvittana may be a suitable insect vector for delivering F. tumidum conidia on gorse using this novel biocontrol strategy. Although it is a polyphagous insect, and may visit non-target plants, F. tumidum is a very specific pathogen of gorse, broom and a few closely related plant species. Hence, using this insect species to vector F. tumidum in a biological control programme, should not pose a significant threat to plants of economic importance. However, successful control of gorse using this "lure-load-infect" concept would depend, to a large extent on the virulence of the pathogen as insects, due to the large size of F. tumidum macroconidia, can carry only a small number of it.

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Dissertations / Theses on the topic 'Insect pests – Biological control'

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