Tesis: "Pests Biological control"

1

Garcia, André Filipe Fidalgo Casquilho. "Enhancing biological control against Eucalyptus pests." Doctoral thesis, ISA, 2020. http://hdl.handle.net/10400.5/21212.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Linkous, Emily Kathryn. "Integrating biological control and chemical control of cabbage caterpillar pests." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366362436.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Solà, Cassi Mireia. "Approaches for the biological control of stored product pests." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/461300.

Texto completo

Resumen

Stored products include all postharvest agricultural foodstuffs that do not require refrigeration and that can be preserved for several months under proper conditions as cereal grain and other raw material or processed food. Regrettably, in the Mediterranean region, the presence of insect pests such as the internal feeders of grain: Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), Sitophilus spp. (S. granarius (L.), S. oryzae (L.) and S. zeamais (Motschulsky)) (Coleoptera: Curculionidae) and Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) as well as the moth usually present in warehouses and grain mills, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae), induce important quantitative and qualitative damage before consumption. Among the integrated pest management strategies for the control of these concerning stored product pests, biological control with the introduction of parasitoids as natural enemies represents a good alternative to the use of pesticides. Unfortunately, for the correct implementation and success of this sustainable approach, higher management knowledge is required. For this reason, the aim of this thesis was to assess different biological control approaches for the control of the most important stored product pests. A major issue for the cereal industry is the early detection of insects during grain storage and processing, especially when immature stages of the pests are hidden inside the grain kernels, such as happens with the internal feeders. Then, the first two chapters of this thesis are dedicated to the development of two Polymerase Chain Reaction (PCR) methodologies for internal feeder’s diagnosis. First, in chapter 1, a realtime PCR (qPCR) protocol for the detection and quantification of R. dominica in rice as a model system to quantify internal feeders in grain with a simple methodology is presented. On the other side, in chapter 2, a multiplex PCR protocol for the simultaneous detection and identification of the five most prevalent internal feeder pest species in different grains and processed food is described and then, also tested with commercial samples. For the effective use of natural enemies it is vital to understand and consider the interactions among physical, chemical and biological factors that take place when the grain is stored. For this reason, the third chapter of the thesis is focused on assessing the effectiveness of the parasitoid Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) released in three different densities (10♀♀, 20♀♀ or 40♀♀ parasitoids) to control high infestations of the weevils R. dominica and S. zeamais in two kilos of rice under two risk temperatures (23ºC and 28ºC). The last chapter of the thesis is devoted to the optimization of an economic and easy to use device called Bankerbox for the control of the moth E. kuehniella by rearing and progressively releasing the parasitoid Habrobracon hebetor (Hüber) (Hymenoptera: Braconidae). In this perfectionated Bankerbox version, to avoid the risk of contamination of the stored products, Galleria mellonella (Lepidoptera: Pyralidae) larvae was chosen as host to rear the parasitoid. Then, three different treatments were tested, one with E. kuehniella 4th instar larvae and two with G. mellonella: one containing 4th instar larvae and the other with mixed larval stages (2nd and 4th instar larvae). The research carried out in this thesis attends to increase the knowledge for the proper use of integrated pest management strategies by providing feasible alternatives to the use of pesticides in the stored product industry for the control stored product pests.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

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.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Begum, Mahmuda. "Habitat manipulation to enhance biological control of lightbrown apple moth (Epiphyas postvittana) /." Connect to full text, 2004. http://hdl.handle.net/2123/690.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Ahmad, Mahmood. "Initial frequencies of alleles for resistance to Bacillus thuringiensis toxins in field populations of Plutella xylostella and Helicoverpa armigera." Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09pha2851.pdf.

Texto completo

Resumen

Leaves 101-104 are misnumbered. Bibliography: leaves 155-215. In this study thirteen populations of P. xylostella from crucifer growing areas of Queensland, Victoria, Tasmania, South Australia and Western Australia were surveyed for resistance to Bt (Bacillus thuringiensis) toxins using a leaf-dip bioassay method.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

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.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Tilly, Gaoh Abdouramane. "Potential of selected natural products as repellents against vertebrate pests of crops." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ50896.pdf.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

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.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

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

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

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.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Neethling, Jacob van der Westhuizen. "Biologiese beheer van plantparasitiese nematodes met die swam Paecilomyces lilacinus by aartappels, sitrus en wingerd." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53311.

Texto completo

Resumen

Thesis (MSc)--Stellenbosch University, 2003. ENGLISH ABSTRACT: Paecilomyces Ii/acinus, ras 251 (geregistreer in terme van wet 36 van 1947 as Suid-Afrika se eerste natuurlike nematisiede en kommersieel beskikbaar as PI Plus) is as biologiese beheer agent getoets by aartappels en in geïntegreerde beheer programme by sitrus en wingerd teen respektiewelik Me/oidogyne species, Ty/enchu/us semipenetrans en verskeie ektoparasitiese nematodes. Die swam toon belofte vir die beheer van hierdie nematodes en het terselfdertyd nie 'n nadelige effek op nie-teiken, voordelige organismes in die grond nie. Veral in kombinasie met chemiese middels, as deel van geïntegreerde programme, kan dit lei tot verminderde gebruik van hoogs toksiese middels en dus meer omgewingsvriendelike landboupraktyke. Biological control of plant parasitic nematodes on potatoes, citrus and grapevine with the fungus, Paecilomyces liIacinus. Paecilomyces liIacinus, race 251 (registered in terms of act 36 of 1947 as South Africa's first natural nematicide, commercially available as PI Plus) was tested as a biological control agent on potatoes and in integrated control programs on citrus and grapevine against Me/oidogyne species, Ty/enchu/us semipenetrans and various ectoparasitic nematodes respectively. The fungus shows promise for the control of these nematodes, without having a harmful effect on non-target, beneficial organisms in the soil. Especially in combination with chemical products, as part of integrated programs, this can lead to less use of highly toxic compounds and thus to more environmentally friendly agricultural practices. AFRIKAANSE OPSOMMING: Sedert die ontdekking van die swam, Paeci/omyces Ii/acinus (Thom.) Samson as 'n effektiewe eierparasiet van Meloidogyne incognita acrita en Globodera pal/ida (Jatala et al., 1979) het verdere veldproewe in Peru tot die effektiewe beheer van M. incognita en Tylenchulus semipenetrans gelei. Na verskeie suksesse in Peru is die swam onder verskillende klimaat- en grondkondisies in verskeie ander lande beproef. Die sukses behaal in die Filippyne het gelei tot die kommersiële produksie van die swam onder die handelsnaam Biocon. Anders as met chemiese middels vind die werking van biologiese agente stadig oor tyd plaas. Biologiese beheer sal nie chemiese beheer sonder meer kan vervang nie. Dit behoort egter deel te vorm van geïntegreerde nematode bestuur. Inkorporering van die natuurlike organismes, die oordeelkundige gebruik van chemiese nematisiedes, moontlik in kombinasie met die biobeheer agente, weerstand, en ander kulturele praktyke moet ernstig oorweeg word as ons hoop om die steeds groeiende wêreldbevolking te voed (Jatala, 1986). Paecilomyces liIacinus, ras 251, Suid-Afrika se eerste geregistreerde natuurlike nematisiede, kommersieel beskikbaar as PI Plus, is in die Olifantsrivier besproeiingsgebied geëvalueer vir die bestuur van ekonomies belangrike plantparasitiese nematodes by aartappels, sitrus en wingerd. Hierdie gewasse is belangrike bedryfstakke van die streek en is onderhewig aan skade deur nematodes wat die opbrengs nadelig beïnvloed. Chemiese beheer bied slegs 'n korttermyn oplossing vir nematode probleme en skadelike getalle word in 'n kort tyd weer opgebou. Boonop lei dié hoogs toksiese middels tot agteruitgang van die omgewing en sy waterbronne. Die toenemende besorgdheid hieroor en die groot potensiaal van biologiese beheer agente (Jatala, 1986) was die hoofrede vir die werk waaroor hier gerapporteer word.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Verleur, Peter Marcel. "Development of biological control strategies against sirex noctilio (Fabricius) on Sappi Forests (Ltd) Landholdings in the summer rainfall regions of South Africa." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/1273.

Texto completo

Resumen

The commercial forest industry in South Africa is predominantly dependent on large tracts of exotic monoculture plantations. While this simplifies management practice, there is always the inherent danger posed by introduced pests and diseases. Classical biological control is usually the most effective control method against introduced exotic pests. Climatic factors and seasonal differences may negatively affect the ability of the natural enemies to establish successfully at the new location. Successful establishment of the natural enemies usually results in control over the pest within four years. Sirex noctilio naturally occurs in the mediterranean countries of Europe and North Africa. It is the only member of the Siricid family capable of killing living pine trees. Sirex noctilio was accidentally introduced into New Zealand from Europe during the early 1900s. It has since been found in Australia, Brazil, Argentina South Africa and Chile. Initial biological control in New Zealand and Tasmania was through the release of Siricid specific parasitoid wasps from Europe and North America. The discovery of the accidental introduction of the entomophagous nematode Beddingia siricidicola and its subsequent artificial culturing for release provided the platform for the biological control methodology, which brought the Sirex woodwasp under control. The methods and natural enemies used in New Zealand and Australia were introduced by the South American countries and in the Western Cape of South Africa. Successful biological control was achieved in the Western Cape within two years after the initial introduction of the nematode B. siricidicola. The migration of S. noctilio into the summer rainfall regions of South Africa occurred in the absence of the associated natural enemies. This resulted in rapid population growth of the pest and substantial damage was caused to plantations of Pinus patula in the Eastern Cape and KwaZulu-Natal. Initial attempts at introducing B. siricidicola during 2004 were not very successful. This study contributes to the understanding and adaptation of the biological control methods to the summer rainfall climate. The key finding was that in the summer rainfall climate, only the bottom third of nematode inoculated S. noctilio infested trees produced parasitized adults during the emergence period. A comparative study was done on log samples from S. noctilio infested trees collected in the Western Cape and KwaZulu-Natal. iv An adapted nematode inoculation technique for pulpwood plantations in the summer rainfall regions was developed and implemented in mass inoculations with B. siricidicola during 2007 and 2008. Locally available herbicides were tested for suitability of use in the establishment of trap trees, which would attract ovipositing S. noctilio females in situations where low numbers of the woodwasp occur. Determination of the levels of natural B. siricidicola parasitism in S. noctilio adults during the 2008 emergence period indicate successful establishment of the nematode in KwaZulu-Natal. Successful introduction of the parasitoid wasp Ibalia leucospoides into the summer rainfall regions has also been achieved.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

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.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

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

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Moore, Sean Douglas. "The biology of a facultative hyperparasitoid, Tetrastichus Howardi Olliff (Hymenoptera : Eulophidae), and its potential as a biocontrol agent of lepidopterous stem borers." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005331.

Texto completo

Resumen

The gregarious pupal endoparasitoid, Tetrastichus howardi Olliff (Hymenoptera: Eulophidae), was introduced into South Africa as a biocontrol agent against the maize and the sorghum stem borers, Busseola fusca Fuller and Chilo partellus Swinhoe. Preovipositional behaviour, ovipositional behaviour, development, fertility, sex-ratio, and longevity were studied in the laboratory. A complex courtship behaviour was observed, however 35.3% of females were mated before emergence from the host pupa. Preoviposition period ranged from 100 mins up to 5 days. Host searching time in Petri dishes was shorter for lepidopteran pupae than for their parasitoid pupae, and shortest when T. howardi had previously experienced the host. Duration of oviposition was significantly longer in the lepidopteran pupae than in the smaller tachinid puparia. T. howardi showed no difference in preference for hosts of different ages. The lepidopteran hosts were preferred to their parasitoids. If T. howardi had previously experienced a certain host its pereference for that host tended to increase, but not significantly. When reared on a certain host, the preference for that host did increase. The parasitoid was able to discriminate between parasitzed and unparasitzed pupae although this ability developed only 2 days after the pupa was parasitized. Cotesia sesamiae Cameron, the main indigenous parasitoid of B. fusca and C. partellus, was not attacked by T howardi. The total duration of development from egg deposition to the adult stage ranged from 18 to 26 days at 24°C and 60% RH. Emergence of adults began after first light, mean emergence time in winter being 09h00. Emergence rate of T. howardi from parasitized hosts, and mortality rate of parasitized hosts, was higher for C. partellus and H. armigera than for Eldana saccharina Walker and Palexorista laxa Curran. This decreased for C. partellus and H. armigera when superparasitized. A strong correlation existed between total parasitoids emerging from a host and percentage of females. When a lepidopteran pupa was parasitized by a single T. howardi female, 55 progeny emerged of which 94% were females. Larger females showed greater fertility and also produced a higher percentage of females. Younger hosts were more suitable for development of T. howardi. Females lived for 5.4 to 52.5 days, and males lived for 3.1 to 28.6 days, depending on presence or absence of food, water and hosts. Reasons for releasing T. howardi in the field are discussed. Only 2 recoveries of parasitized C. partellus pupae were made from the field.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

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.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Ludewig, Michael Hans. "The establishment of a virus free laboratory colony of Cryptophlebia leucotreta (False Codling Moth) and characterisation of Cryptophlebia leucotreta Granulovirus (CrleGV) genes." Thesis, Rhodes University, 2003. http://hdl.handle.net/10962/d1004016.

Texto completo

Resumen

Cryptophlebia leucotreta is an economically important agricultural pest throughout Sub-Saharan Africa. CrleGV has been considered as an alternative to chemical control of this pest due to its host specificity and innocuous nature towards vertebrates. A CrleGV free laboratory colony of C. leucotreta would be useful for the isolation of genotypically pure strains of the CrleGV and for virulence comparisons between isolates. It is preferable to have a full characterisation of CrleGV prior to its registration and release into the environment as a biopesticide. A laboratory colony of C. leucotreta, set up at Rhodes University, containing a low level of infection indicated that CrleGV is vertically transmitted. To establish a virus free laboratory colony of C. leucotreta, a solution of 3.5% sodium hypochlorite and 1% Tween 20 was used to surface decontaminate C. leucotreta eggs for removal of transovum CrleGV from the laboratory colony. No apparent infection by CrleGV was induced by subjecting larvae to stress. PCR of DNA extracted from larvae using CTAB failed to detect virus in the laboratory colony. This detection protocol was able to detect down to 60 fg (480 genome copies of CrleGV). The possibility of low-level virus remaining in the colony requires monitoring of genotypic purity of virus manipulated in the colony. Sequencing of Bam HI/KpnI fragments produced a preliminary sequence of the granulin region of CrleGV. This preliminary sequence supports the trend that the gene organisation of the granulin region of the granuloviruses infecting the family Tortricidae is conserved.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Heunis, J. M. (Juanita Maria). "The influence of synthetic pyrethroids on phytophagous mites and their natural enemies in apple orchards." Thesis, Stellenbosch : Stellenbosch University, 1992. http://hdl.handle.net/10019.1/69805.

Texto completo

Resumen

Thesis (MSc)--Stellenbosch University, 1992. One copy microfiche. ENGLISH ABSTRACT: The effects of synthetic pyrethroids on the spider mite, Tetranychus urticae Koch, and its natural enemies was investigated. The pyrethroid cyfluthrin, sprayed for the control of fruit weevil Phlyctinus callosus, did not cause mite outbreaks and was not harmful to the predators when sprayed before they appeared on the apple trees. This spray also gave good control of thrips, bollworm (Heliothis armigera) and fruit weevil (P. callosus). A late season spray of deltamethrin against codling moth, caused an increase in the phytophagous mite population. This was assosiated with a temporary reduction in the population level of the predatory beetle, Oligota fageli. The plants found on the orchard floor were examined. The plant diversity was low and plants that acted as hosts of phytophagous mites during the winter were scarce. However, Solanum nigum carried high mite populations and infected the adjacent apple trees. The plants were too few to have an effect on the whole orchard. Eight synthetic pyrethroids were tested for repellency in a leafdisk dip and spray bioassay using T. urticae. Deltamethrin and fenvalerate caused no walk-off. Cyfluthrin and fluvalinate caused moderate walk-off and bifenthrin, cyhalothrin and lambda-cyhalothrin caused high walk-off. AFRIKAANSE OPSOMMING: Die invloed van sintetiese piretroIedes op die rooispinmyt, Tetranychus urticae Koch en hul natuurlike vyande is ondersoek. Die piretroIed, cyfluthrin, gespuit vir die beheer van snuitkewer, P4ctinus callosus, het the mytuitbrake veroorsaak the en was ook the skadelik vir predatore nadat dit vroeg in die seisoen, voordat myte in die appelbome verskyn het, gespuit is the. Die bespuiting het ook goeie beheer van blaaspootjies, bolwurm (Heliothis amdgera) en P. callosus gegee. Deltametrien wat later in die seisoen toegedien is vir die beheer van kodlingmot, Cydia pomonella, het 'n mytuitbraak veroorsaak. Dit word geassossieer met die tydelike onderdrukking van die populasievlak van die predatoriese kewer, Oligota fageli. Die plante in die dekgewas is ondersoek. Die plant-verskeidenheid was laag en plante wat kon dien as oorwinterings gashere vir fitofage myte kon dien was skaars. Solanum nigrum het egter groot bevolkings myte gedra wat die appelbome naaste aan hulle eerste besmet het. Daar was egter te min van hierdie plante om 'n invloed op die hele boord te he. Agt piretroIedes is vir afwering van T. urticae in 'n blaarskyf doop en spuit bioessal getoets. Deltamethrin en fenvalerate het geen afwering getoon the. Cyfluthrin en fluvalinate het 'n redelike afwering, terwyl bifenthrin, cyhalothrin en lamda-cyhalothrin het 'n hod mate van afwering getoon

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Mdlangu, Thabisa Lynette Honey. "Influence of mite predation on the efficacy of the gall midge Dasineura sp. as a biocontrol agent of Australian myrtle Leptospermum laevigatum (Myrtaceae) in South Africa." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/272.

Texto completo

Resumen

Dasineura sp. is a gall forming midge that was introduced into South Africa for the biocontrol of the Australian myrtle, Leptospermum laevigatum. It causes galls on both the vegetative and reproductive buds of the plant. Although Dasineura sp. was initially regarded as a potentially successful agent, galling up to 99 percent of the buds of the host plant, it has been preyed on by native opportunistic mites, which caused a decline in the performance of the midge as a biocontrol agent of L. laevigatum. This raised a concern about whether this fly will be able to perform effectively in the presence of its new natural enemies. Therefore, the objectives of this study were to: 1) ascertain whether mite abundance has seasonal variations; 2) determine if plant density and plant size have an effect on midge predation by the mites; and 3) determine if midge predation varies in different locations. The study was conducted at three sites in the Hermanus area, Western Cape Province. Every three weeks for thirteen months, galls were collected and dissected so as to count and record the numbers of midge larvae, pupae, adults and mites that were found. Data collected showed that predation varied with season, and the mites were scarce during the flowering season. Predation also varied among the study sites and plant density had an effect on midge predation. Midges in smaller plants (saplings) were more vulnerable to predation than those in the bigger plants (plants from isolates and thickets). It was concluded that although mites have an effect on midge populations, they do not prevent their establishment on the plant. Therefore, a survey should be done in two to three years time to check if the midges are still persisting on the plant, vi and recommendations are that a new agent should be released to supplement the midges.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Moore, Gareth Ryan. "The role of nutrients in the biological control of water lettuce, Pistia stratiotes lamarck (Araceae) by the leaf-feeding weevil, Neohydronomus affinis Hustache (Coleoptera: Curculionidae) with particular reference to eutrophic conditions." Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1005447.

Texto completo

Resumen

Water lettuce, Pistia stratiotes Lamarck (Araceae) is a South American plant that has the potential to be a very damaging and important aquatic weed in many tropical countries, including South Africa. It has the potential to rapidly multiply vegetatively and completely cover watercourses in a very short space of time outside of its natural range under ideal conditions and without its natural enemies. In such instances, the weed may cause hindrances to water transport and fishing, increasing chances of malaria, as well as affecting the natural ecology of the system. Water lettuce can also set seed, which may lay dormant for long periods, germinating when conditions are favourable. It is therefore very necessary to adopt control methods against the weed where it is a problem. However, water lettuce has also been effectively and completely controlled in many countries by the leaf-feeding weevil, Neohydronomus affinis Hustache. High nutrient levels in the form of nitrates and phosphates have been shown to have largely negative effects on biological control in several studies, with control being incomplete or taking longer than in similar areas with lower nutrient levels. The effectiveness of N. affinis on the biological control of water lettuce was investigated in a laboratory study, growing P. stratiotes plants with and without insects at different nutrient concentrations. In these studies biological control of water lettuce with N. affinis was found to be complete under eutrophic nutrient conditions, although control took longer when higher nutrient levels were tested. A field site study was conducted at a sewage settlement pond in Cape Recife Nature Reserve near Port Elizabeth, South Africa. This highly eutrophic system was used as a field example for the effectiveness of biocontrol of P. stratiotes by N. affinis under eutrophic conditions. The weevils at Cape Recife caused a massive and rapid crash in the percentage coverage of the weed, from 100% in May 2003, to approximately 0.5 % in September 2003. Plant growth parameters were also found to decrease considerably in size correspondingly with this crash from May 2003 until spring 2003. Plant size only again started to increase gradually but steadily through spring 2003 and into summer. In the laboratory studies, the fecundity of weevils was shown to be much higher on plants grown under higher nutrient concentrations than on plants grown in lower nutrient concentrations. The results from the wing-muscle analysis under different nutrient concentrations were not easy to interpret, and there were few differences in wing muscle state between most of the concentrations. From these findings it is suggested that nutrient concentration, particularly high levels of nitrates and phosphates is not a limiting factor in terms of effective biological control of P. stratiotes with N. affinis, but that under high nutrient conditions biological control might take longer.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

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.

Texto completo

Resumen

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

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

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.

Buscar texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Godin, Claude 1970. "Seasonal occurrence and parasitism of lepidopterous pests of crucifers, and host age selection by a potential control agent: Trichogramma." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27327.

Texto completo

Resumen

During a two years study (1993-1994) in southwestern Quebec, Artogeia rapae and Plutella xylostella were found to be the most important lepidopterous pests of cruciferous crops, followed by Trichoplusia ni and four minor species. The relationship between plant sampling and the use of degree-days, pheromone traps (P. xylostella) or butterflies counts (A. rapae) was assessed for A. rapae and P. xylostella. Three generations of A. rapae were observed annually, with a duration of 319.7 degree-days above $ rm 10 sp circ C (DD sb{10}),$ while P. xylostella had three to four generations with a duration of 277.7 $ rm DD sb{10}.$ Captures of P. xylostella were not linked to the level of infestations. By the end of summer, A. rapae was the most abundant species, especially on broccoli, while P. xylostella was often abundant early in the season. The complex of lepidopterous pests' natural enemies was identified, and the data were analyzed using an illustrated parasitoid web. Fourteen parasitoid and three hyperparasitoid species (12 Hymenoptera, 2 Diptera) were identified. The most important parasitoid, Cotesia rubecula, is a larval parasitoid of A. rapae that is newly established in Quebec. Overall, parasitism of lepidopterous eggs is almost not existent, whereas parasitism and infection of larvae and pupae by pathogens are important, but not significant to reduce butterfly populations. In order to evaluate the potential of oophagous parasitoids, the parasitism of up to 42 species/strains of Trichogramma was studied with different development stages of P. xylostella, A. rapae and T. ni eggs. Generally, Trichogramma females attacked preferably young eggs of a given host species. Females modified the number of offspring according to host size and host age, as fewer offspring emerged from the smallest or the oldest hosts. Host age had no impact on sex allocation. (Abstract shortened by UMI.)

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Bueno, Nádia Maebara [UNESP]. "Bases biológicas para utilização de Trichospilus diatraeae (Hymenoptera: Eulophidae) para controle de Helicoverpa armigera (Lepidoptera: Noctuidae)." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/131920.

Texto completo

Resumen

Made available in DSpace on 2015-12-10T14:22:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-07-23. Added 1 bitstream(s) on 2015-12-10T14:28:41Z : No. of bitstreams: 1 000853174.pdf: 327916 bytes, checksum: 8b80e5d10c5f87704a801b1cac7b55a1 (MD5) A espécie Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) é um inseto polífago, com ampla distribuição geográfica e considerada uma importante praga nas regiões do mundo em que ocorre. Na safra 2013/2014, a presença desse lepidóptero foi registrada pela primeira vez no Brasil, acarretando em perdas de produtividade. Essa espécie possui diversas características que a tornam de indiscutível importância, como o fato de dispersarse a longas distâncias, alimentar-se na fase jovem de estruturas reprodutivas das plantas, alta fertilidade e diapausa facultativa das pupas. Além disso, é uma espécie que apresenta resistência a um grande número de inseticidas. Diante desse cenário, outras táticas de controle, que englobem técnicas inter e multidisciplinares, devem ser adotadas, de acordo com a proposta do Manejo Integrado de Pragas. Uma delas, o controle biológico, apresenta grande potencial, pois não causa desequilíbrio ambiental e pode manter a população de pragas abaixo do nível de dano econômico. Nesse sentido, o parasitoide de pupas Trichospilus diatraeae Cherian & Margabandhu (Hymenoptera: Eulophidae) apresenta potencial de utilização no controle dessa praga. T. diatraeae é uma espécie amplamente distribuída no território brasileiro e foi registrado em diversas famílias de Lepidoptera, o que o caracteriza como altamente polífago. Para tanto, é necessário conhecer previamente as interações entre parasitoide e hospedeiro alvo, tornando importante estudar essas características. Sendo assim, o objetivo deste trabalho foi estudar as características biológicas do parasitoide em diferentes hospedeiros, a influência do sexo e idade da pupa, idade e densidade de parasitoides e tempo de parasitismo, além do estudo do desenvolvimento em diferentes temperaturas de T. diatraeae em pupas de H. armigera. Concluiu-se que T. diatraeae desenvolveu-se melhor a 25ºC, em pupas ... Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a polyphagous insect, with wild geographic distribution and considered the most important pest in the regions where it occurs. Recently, in the 2013/2014 growing season, its presence was first registered in Brazil, bringing yield loss and therefore economic damages. This species has several characteristics that make it of considerable interest, such as the fact of its capacity in disperse over long distances, caterpillars that feeds of reproductive structures, high fertility and optional diapause pupae. Furthermore, it is a species that is resistant to a large number of insecticides. In this scenario, other control tactics, covering inter and multidisciplinary techniques should be adopted in accordance with the proposal of Integrated Pest Management (IPM). One of them, biological control, has great potential because it does not cause environmental imbalance and can keep the pest population below economic injury level. In this sense, the pupae parasitoid Trichospilus diatraeae Cherian & Margabandhu (Hymenoptera: Eulophidae) presents potential to be utilizated in biological control. T. diatraeae is a widely distributed species in Brazil, and have already been recorded in several Lepidopteran families, which characterizes this insect as highly polyphagous. Therefore, it is necessary to know the interactions between parasitoid and host, making it important to study these characteristics. Thus, the objective of this work was to study the ...

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Bueno, Nádia Maebara 1988. "Bases biológicas para utilização de Trichospilus diatraeae (Hymenoptera: Eulophidae) para controle de Helicoverpa armigera (Lepidoptera: Noctuidae) /." Botucatu, 2015. http://hdl.handle.net/11449/131920.

Texto completo

Resumen

Orientador: Regiane Cristina Oliveira de Freitas Bueno Coorientador: Carlos Frederico Wilcken Banca:Everton Pires Soliman Banca: Valmir Antonio Costa Resumo: A espécie Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) é um inseto polífago, com ampla distribuição geográfica e considerada uma importante praga nas regiões do mundo em que ocorre. Na safra 2013/2014, a presença desse lepidóptero foi registrada pela primeira vez no Brasil, acarretando em perdas de produtividade. Essa espécie possui diversas características que a tornam de indiscutível importância, como o fato de dispersarse a longas distâncias, alimentar-se na fase jovem de estruturas reprodutivas das plantas, alta fertilidade e diapausa facultativa das pupas. Além disso, é uma espécie que apresenta resistência a um grande número de inseticidas. Diante desse cenário, outras táticas de controle, que englobem técnicas inter e multidisciplinares, devem ser adotadas, de acordo com a proposta do Manejo Integrado de Pragas. Uma delas, o controle biológico, apresenta grande potencial, pois não causa desequilíbrio ambiental e pode manter a população de pragas abaixo do nível de dano econômico. Nesse sentido, o parasitoide de pupas Trichospilus diatraeae Cherian & Margabandhu (Hymenoptera: Eulophidae) apresenta potencial de utilização no controle dessa praga. T. diatraeae é uma espécie amplamente distribuída no território brasileiro e foi registrado em diversas famílias de Lepidoptera, o que o caracteriza como altamente polífago. Para tanto, é necessário conhecer previamente as interações entre parasitoide e hospedeiro alvo, tornando importante estudar essas características. Sendo assim, o objetivo deste trabalho foi estudar as características biológicas do parasitoide em diferentes hospedeiros, a influência do sexo e idade da pupa, idade e densidade de parasitoides e tempo de parasitismo, além do estudo do desenvolvimento em diferentes temperaturas de T. diatraeae em pupas de H. armigera. Concluiu-se que T. diatraeae desenvolveu-se melhor a 25ºC, em pupas ... Abstract: Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a polyphagous insect, with wild geographic distribution and considered the most important pest in the regions where it occurs. Recently, in the 2013/2014 growing season, its presence was first registered in Brazil, bringing yield loss and therefore economic damages. This species has several characteristics that make it of considerable interest, such as the fact of its capacity in disperse over long distances, caterpillars that feeds of reproductive structures, high fertility and optional diapause pupae. Furthermore, it is a species that is resistant to a large number of insecticides. In this scenario, other control tactics, covering inter and multidisciplinary techniques should be adopted in accordance with the proposal of Integrated Pest Management (IPM). One of them, biological control, has great potential because it does not cause environmental imbalance and can keep the pest population below economic injury level. In this sense, the pupae parasitoid Trichospilus diatraeae Cherian & Margabandhu (Hymenoptera: Eulophidae) presents potential to be utilizated in biological control. T. diatraeae is a widely distributed species in Brazil, and have already been recorded in several Lepidopteran families, which characterizes this insect as highly polyphagous. Therefore, it is necessary to know the interactions between parasitoid and host, making it important to study these characteristics. Thus, the objective of this work was to study the ... Mestre

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

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.

Texto completo

Resumen

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

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Calabuig, Gomar Altea. "Ants, pests and natural enemies in Mediterranean citrus. Ecological interactions and practical implications for biological control." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/54122.

Texto completo

Resumen

[EN] Ants constitute an important component of the citrus agroecosystem fauna acting simultaneously as predators and as hemipteran mutualists. Thus, ants in citrus are in the center of a complex food web affecting the composition and the population dynamics of a wide arthropod community including honeydew and non-honeydew producing herbivores as well as their natural enemies. In eastern Spain the most abundant and widespread ant species are the natives Lasius grandis Forel and Pheidole pallidula (Nylander), whereas the invasive Linepithema humile (Mayr) is also present but not widespread. We have conducted ant-exclusion experiments in three commercial citrus orchards, each one dominated by one ant species (Pheidole pallidula, Lasius grandis or Linepithema humile) with the aim to disentangle the ecological interactions with honeydew and non-honeydew producing pests and with natural enemies at the community-level. We quantified the effect of the ant-exclusion on the infestation levels and parasitism of three of the most important citrus pests in the area, the honeydew producer Aleurothrixus floccosus (Maskell) and the non-honeydew producers Aonidiella aurantii (Maskell) and Phyllocnistis citrella (Stainton). California red scale densities on fruits were significantly lower in the two seasons and in the three orchards in the ant-excluded treatment. Similarly, the percentage of shoots occupied by A. floccosus was significantly lower in the ant-excluded plots in the orchards dominated by P. pallidula and L. humile. Interestingly, no significant differences were found in the percent parasitism between ant-allowed and ant-excluded treatments. These results suggest that factors other than parasitoid disruption might explain the increased pest populations observed in the presence of ants. Thus, in the same orchards we compared the abundance, species richness, diversity and community structure of predators and parasitoids between the ant-allowed and ant excluded treatments. A total of 176,000 arthropods belonging to 81 taxa were captured and identified. Regarding abundance, the response of natural enemies to ant-exclusion was species specific. When examining functional groups, parasitoids showed higher abundances in the ant-allowed treatment whereas most generalist predators were less abundant. Similarly, the species richness and the Shannon diversity index of parasitoids were higher in the ant-allowed treatment, whereas the species richness of predators was significantly lower. The community structure of predators and parasitoids was not significantly different between treatments. Thus, ants were not associated with a dramatic and/or general decrease in natural enemy abundance or biodiversity. On the other hand, the negative impact of ants on generalist predators may have important implications for the regulation of pest populations. Finally we tested a novel hypothesis examining the potential competition between ants and natural enemies for honeydew produced by Hemiptera. Through the use of high performance liquid chromatography (HPLC) we related the level of ant activity with the energy reserves and feeding history of individual specimens collected in the field. A significant negative correlation between ant activity and the total sugar content and honeydew feeding incidence by A. chrysomphali was found in summer, when ant activity peaked. Ant activity was negatively correlated with the sugar feeding incidence by C. carnea in spring. This is a previously undocumented indirect interaction in food webs in which ants interfere with the physiological state of the natural enemies. Given that the absence of sugar feeding is detrimental for the fitness of many species of predators and parasitoids, this interaction may have important consequences for the arthropod community composition and practical implications for biological control. [ES] Las hormigas constituyen un elemento importante del agroecosistema de los cítricos, en el que actúan simultáneamente como insectos depredadores y como mutualistas de hemípteros. Como consecuencia, las hormigas pueden afectar a la composición y a la dinámica poblacional de un amplio grupo de artrópodos, en los que se incluye herbívoros productores y no productores de melaza, así como a sus enemigos naturales. Se han llevado a cabo estudios de exclusión de hormigas en tres parcelas comerciales de cítricos en las que, en cada una de ellas, predominaba una especie de hormiga (Lasius grandis Forel, Pheidole pallidula (Nylander) y Linepithema humile (Mayr)). El principal objetivo ha sido el de esclarecer las interacciones ecológicas existentes entre las hormigas y los artrópodos productores y no productores de melaza, así como con los enemigos naturales a nivel de comunidad. Se ha cuantificado el efecto de la exclusión de hormigas sobre los niveles de infestación y el parasitismo de tres de las plagas más importantes de los cítricos de la zona, la plaga productora de melaza Aleurothrixus floccosus (Maskell) y las plagas que no producen melaza Aonidiella aurantii (Maskell) y Phyllocnistis citrella (Stainton). Las densidades poblacionales de A. aurantii en frutos i de A. floccosus fueron significativamente menores en el tratamiento de exclusión de hormigas. Curiosamente, no se encontraron diferencias en el porcentaje de parasitismo entre los dos tratamientos. Estos resultados sugieren que otros factores, más allá de la interferencia con los parasitoides, podrían explicar los incrementos poblacionales de plagas observados en presencia de hormigas. Por ello, se comparó la abundancia, riqueza de especies, diversidad y estructura de la comunidad de depredadores y parasitoides entre los tratamientos de exclusión y presencia de hormigas. Se capturaron e identificaron un total de 176,000 artrópodos pertenecientes a 81 taxones distintos. En cuanto a la abundancia, la respuesta de los enemigos naturales a la exclusión de hormigas fue específica para cada especie. Los parasitoides mostraron mayores abundancias en presencia de hormigas, mientras que la mayoría de los depredadores generalistas fueron menos abundantes. De igual modo, la riqueza de especies y el Índice de diversidad de Shannon de los parasitoides fueron mayores en presencia de hormigas, mientras que la riqueza de especies de los depredadores fue menor. La estructura de la comunidad de depredadores y parasitoides no difirió entre tratamientos. El impacto negativo de las hormigas sobre los depredadores generalistas puede tener importantes implicaciones sobre la regulación de las poblaciones de plagas. Finalmente, se estudió una novedosa hipótesis en la que se planteó la existencia de competencia por la melaza que producen los hemípteros, entre las hormigas y los enemigos naturales. Mediante el uso de cromatografía líquida de alta resolución (HPLC) se relacionó la actividad de las hormigas con las reservas energéticas y las fuentes alimenticias utilizadas por especímenes de enemigos naturales colectados en el campo. Se encontró una correlación significativamente negativa entre la actividad de las hormigas y el contenido total de azúcares y la alimentación a base de melaza del parasitoide Aphytis chrysomphali (Mercet) en verano. La actividad de las hormigas se correlacionó negativamente con la alimentación a base de azúcares del depredador Chrysoperla carnea s.l en primavera. Esta interacción indirecta en la que las hormigas interfieren con el estado fisiológico de los enemigos naturales no ha sido documentada previamente. Dado que la ausencia de azúcares en la alimentación de muchas especies de depredadores y parasitoides es perjudicial para su estado físico, esta interacción puede tener importantes consecuencias para la composición de la comunidad de artrópodos e implicaciones prácticas sobre el control biológico de plagas. [CAT] Les formigues són un element important de l'agroecosistema dels cítrics, en el que poden actuar simultàniament com a insectes depredadors i com a mutualistes d'hemípters. Com a conseqüència, poden afectar a la composició i la dinàmica poblacional d'un ampli grup d'artròpodes, incloent herbívors productors i no productors de melassa així com els seus enemics naturals. Les espècies de formigues més abundants i esteses als cítrics de l'est de la Península Ibèrica són les espècies natives Lasius grandis Forel i Pheidole pallidula (Nylander) mentre que l'espècie invasora Linepithema humile (Mayr) es troba també present però no de forma estesa. S'han dut a terme estudis d'exclusió de formigues en tres parcel·les comercials de cítrics en les que, en cada una d'elles, predominava una de les tres espècies de formigues. El principal objectiu ha estat el d'esclarir les interaccions ecològiques existents entre les formigues i els artròpodes productors i no productors de melassa així com els enemics naturals a nivell de comunitat. S'ha quantificat l'efecte de l'exclusió de formigues sobre els nivells d'infestació i el parasitisme de tres de les plagues més importants dels cítrics de la zona, la plaga productora de melassa Aleurothrixus floccosus (Maskell) i les plagues no productores de melassa Aonidiella aurantii (Maskell) i Phyllocnistis citrella (Stainton). Les densitats poblacionals d' A. aurantii en fruits i d'A. floccosus foren significativament menors en el tractament d'exclusió de formigues. Curiosament, no es trobaren diferències en el percentatge de parasitisme entre els dos tractaments per a ninguna de les plagues estudiades. Aquests resultats suggereixen que altres factors, més enllà de la interferència amb els parasitoides, podrien explicar els increments poblacionals de plagues observats en presència de formigues. Davant aquests resultats, es va comparar l'abundància, riquesa d'espècies, diversitat i estructura de la comunitat de depredadors i parasitoides entre els tractaments d'exclusió i presència de formigues. Es capturaren i identificaren un total de 176,000 artròpodes pertanyents a 81 taxons distints. En quant a l'abundància, la resposta dels enemics naturals a l'exclusió de formigues fou específica per a cada espècie. Els parasitoides mostraren majors abundàncies en presència de formigues mentre que la majoria de depredadors generalistes foren menys abundants. La riquesa d'espècies i l'Índex de diversitat de Shannon dels parasitoides foren majors en presència de formigues mentre que la riquesa d'espècies dels depredadors fou menor. L'estructura de la comunitat de depredadors i parasitoides fou similar entre tractaments. L'impacte negatiu de les formigues sobre els depredadors generalistes pot tenir importants implicacions per a la regulació de les poblacions de plagues. Finalment s'estudià una novedosa hipòtesi en la que es va plantejar l'existència de competència per la melassa que produeixen els hemípters entre les formigues i els enemics naturals. Mitjançant l'ús de cromatografia líquida d'alta resolució (HPLC) es va relacionar l'activitat de les formigues amb les reserves energètiques i les fonts alimentàries utilitzades per espècimens d'enemics naturals recol·lectats al camp. Es va trobar una correlació significativament negativa entre l'activitat de les formigues i el contingut total de sucres i l'alimentació a base de melassa del parasitoide Aphytis chrysomphali (Mercet) en estiu. L'activitat de les formigues es va correlacionar negativament amb l'alimentació a base de sucres del depredador Chrysoperla carnea s.l. en primavera. Aquesta interacció indirecta en la que les formigues interfereixen en l'estat fisiològic dels enemics naturals no ha sigut documentada prèviament. Donat que l'absència de sucres en l'alimentació de moltes espècies de depredadors i parasitoides és perjudicial per al seu estat físic, aquesta interacció pot ten Calabuig Gomar, A. (2015). Ants, pests and natural enemies in Mediterranean citrus. Ecological interactions and practical implications for biological control [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/54122 TESIS

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Opoku-Debrah, John Kwadwo. "Geographic variation in the susceptibility of false colding Moth, Thaumatotibia Leucotreta, populations to a granulovirus (CrleGV-SA)." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/984.

Texto completo

Resumen

The false codling moth (FCM), Thaumatotibia (=Cryptophlebia) leucotreta (Meyrick) (Lepidoptera: Tortricidae) is a serious pest of citrus and other crops in Sub-Saharan Africa. The introduction of the Cryptophlebia leucotreta granulovirus (CrleGV-SA) Cryptogran and Cryptex (biopesticides) has proven to be very effective in the control of FCM. However, markedly lower susceptibility of some codling moth (CM), Cydia pomonella (L.) populations to Cydia pomonella granulovirus (CpGV-M), another granulovirus product used in the control of CM’s in Europe have been reported. Genetic differences between FCM populations in South Africa have also been established. It is therefore possible that differences in the susceptibility of these geographically distinct FCM populations to CrleGV-SA might also exist. To investigate this phenomenon, a benchmark for pathogenecity was established. In continuation of previous work with Cryptogran against the 1st and 5th instar FCM larvae, dose-response relationships were established for all five larval instars of FCM. In surface dose-response bioassays, the LC50 values for the 2nd, 3rd and 4th instars were calculated to be 4.516 x 104, 1.662 x 105 and 2.205 x 106 occlusion bodies (OBs)/ml, respectively. The LC90 values for the 2nd, 3rd and 4th instars were calculated to be 4.287 x 106, 9.992 x 106 and 1.661 x 108 OBs/ml, respectively. Susceptibility to CrleGV-SA was found to decline with larval stage and increase with time of exposure. The protocol was used in guiding bioassays with field collected FCM larvae. Laboratory assays conducted with Cryptogran (at 1.661 x 108 OBs/ml) against field collected FCM larvae from Addo, Kirkwood, Citrusdal and Clanwilliam as well as a standard laboratory colony, showed a significant difference in pathogenecity in only one case. This significant difference was observed between 5th instars from the Addo colony and 5th instars from the other populations. Four geographically distinct FCM colonies from Addo, Citrusdal, Marble Hall and Nelspruit were also established. Since Cryptogran and Cryptex are always targeted against 1st instar FCM larvae in the field, further comparative laboratory assays were conducted with the Addo colony and an old laboratory colony. Cryptogran was significantly more pathogenic than Cryptex against both the Addo and the old colony. However, a high level of heterogeneity was observed in responses within each population.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Kirkman, Wayne. "Understanding and improving the residual efficacy of the cryptophlebia leucotreta granulovirus (Cryptogran)." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1005482.

Texto completo

Resumen

False codling moth (FCM), Thaumatotibia (=Cryptophlebia) leucotreta (Meyr) (Lepidoptera: Tortricidae), is one of the most important pests on citrus. The Cryptophlebia leucotreta granulovirus (CrleGV) has been developed into a successful biological control agent, registered under the name Cryptogran, and is currently the preferred product for the control of FCM on citrus in South Africa. A prerequisite to the continued success of Cryptogran as a means of controlling false codling moth is to understand the factors affecting field persistence of the virus, and to find ways to improve it. The aim of this study was to gain a clearer understanding of the product and the abiotic and biotic factors affecting its persistence in the field, and to investigate methods to improve this persistence. The effect of UV-irradiation on the virus was determined, and various products were tested as UV protectants in laboratory bioassays. Lignin was the most effective additive, and was tested in several field trials, where it also enhanced the efficacy of Cryptogran. Laboratory trials indicated that Cryptogran is rainfast. Cryptogran applications early in the season had a longer period of residual activity than sprays applied closer to harvest. Daytime applications were less effective that evening sprays. Sprays applied coinciding with peaks in pheromone moth trap catches were more effective than those applied between peaks. Biotic factors influencing persistence were investigated. Residual efficacy was longer when treatments were applied to blocks than as single tree treatments. Attempts were made to quantify the effect of the navel end of a navel orange on the field persistence of Cryptogran. Cryptogran was shown to be compatible with many agricultural chemicals used on citrus. Economic thresholds and various cost-benefit analyses are discussed. A list of practical recommendations to growers was drawn up, and possibilities for future research are presented.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Moore, Sean Douglas. "The development and evaluation of Cryptophlebia Leucotreta granulovirus (CrleGV) as a biological control agent for the management of false codling moth, Cryptophlebia Leucotreta, on citrus." Thesis, Rhodes University, 2003. http://hdl.handle.net/10962/d1004001.

Texto completo

Resumen

A granulovirus isolated from Cryptophlebia leucotreta larvae was shown through restriction endonuclease analysis to be a novel strain (CrleGV-SA). No more than one isolate could be identified from a laboratory culture of C. leucotreta. However, a preliminary examination of restricted DNA profiles of isolates from different geographical regions indicated some minor differences. In surface dose bioassays on artificial diet, LC50 and LC90 values with neonate larvae were estimated to be 4.095 x 103 OBs/ml and 1.185 x 105 OBs/ml respectively. LT50 and LT90 values with neonate larvae were estimated to be 4 days 22 h and 7 days 8 h, respectively. Detached fruit (navel orange) bioassays with neonate larvae indicated that virus concentrations that are likely to be effective in the field range from 1.08 x 107 to 3.819 x 1010 OBs/ml. In surface dose bioassays with fifth instar larvae LC50 and LC90 values were estimated to be 2.678 x 107 OBs/ml and 9.118 x 109 OBs/ml respectively. LT50 and LT90 values were estimated to be 7 days 17 h and 9 days 8 h, respectively. A new artificial diet for mass rearing the host was developed. Microbial contamination of diet was significantly reduced by adding nipagin and sorbic acid to the diet and by surface sterilising C. leucotreta eggs with Sporekill. Almost 20 % more eggs were produced from moths reared on the new diet compared to moths reared on the old diet. A further 9 % improvement in egg production and a reduction in the labour required to produce eggs, was made with the development of a new oviposition cage attached to the moth eclosion box. Virus was mass produced in fifth instar C. leucotreta larvae by surface inoculating diet with the LC90. When 300 individuals were placed onto inoculated diet, 56 % of them were recovered six to 11 days later as infected larvae. Mean larval equivalents was 1.158 x 1011 OBs/larva. When larvae and diet were harvested together, highest yields of virus were achieved at eight days after inoculation. Microbial contamination in semi-purified preparations of CrleGV ranged from 176211 to 433594 (OB:CFU ratio). Half-life of CrleGV in the field was estimated to be less than 1 day on the northern aspect of trees and between 3 - 6 days on the southern aspect. Original activity remaining (OAR) of the virus dropped below 50 % after 5 days on the northern aspect of trees and was still at 69 % on the southern aspect of trees after 3 weeks. In field trials, CrleGV reduced C. leucotreta infestation of navel oranges by up to 60 % for a period of 39 days. CrleGV in combination with augmentation of the C. leucotreta egg parasitoid, Trichogrammatoidea cryptophlebiae, reduced infestation by 70 %. The integration of CrleGV into an integrated pest management (IPM) system for the management of C. leucotreta on citrus is proposed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Cormier, Daniel. "Seasonal and chemical ecology of Anaphes listronoti and A. victus (Hymenoptera:Mymaridae), egg parasitoids of the carrot weevil, Listronotus oregonensis (Coleoptera:Curculionidae), in central Ontario." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34935.

Texto completo

Resumen

The carrot weevil, Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae), is an insect pest in carrot production in Ontario. The aim of this study was to survey the egg parasitoids attacking the carrot weevil in carrot fields in Ontario, and elucidate the seasonal and chemical ecology of these natural enemies. Field surveys were conducted during three years in commercial carrot fields in the Holland Marsh and district marshes to detect the presence of carrot weevil egg parasitoids, to determine their geographical distribution and to evaluate the effect of insecticides on the rate of emergence and the activity of parasitoid adults. Two egg parasitoids, Anaphes listronoti Huber and A. victus Huber were found. The dominant species Anaphes listronoti is gregarious, was recovered from most of the sampled fields and was distributed in all sampled marshes whereas the solitary parasitoid A. victus was only sporadically found in the Holland Marsh. These Anaphes species occurred in carrot fields from the end of April to the beginning of September and seasonal parasitism averaged 33% in commercial carrot fields and up to 79% in an untreated plot. The insecticides phosmet, diazinon and cypermethrin used in carrot production, did not affect emergence rate of parasitoid adults indicating that immature stages are protected against insecticide penetration in the host egg. However, insecticide applications decreased parasitism rates and suggest a lethal effect on parasitoid adults by direct contact and insecticide residues, although no difference was observed between treatments. Laboratory studies were performed to determine the existence of a sexual pheromone produced by female A. listronoti using a four-arm olfactometer. An automated system of insect tracking was developed to quantify male behavior in the olfactometer. The response of males to odor emitted by virgin females less than two days of age was measured. Virgin females less than one-day-old released a long-range pheromone from 4 hours until 16 hours after the onset of the photophase. Females of one and two days of age started to emit the sexual pheromone earlier than younger females.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

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.

Texto completo

Resumen

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

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

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.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

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/.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Passerini, Julien. "Field and laboratory trials in Mali to determine the effects of neem extracts on three millet pests, Heliocheilus albipunctella De Joannis (Lepidoptera: Noctuidae), Coniesta ignefusalis Hampson (Lepidoptera: Pyralidae) and Kraussaria angulifera Krauss (Orthoptera: Acrididae)." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60451.

Texto completo

Resumen

Formulations of aqueous neem extracts were sprayed in field experiments. Results showed that a 0.5% and 1% concentrations were effective in reducing grasshopper feeding and diminishing damage caused by the millet stemborer, C. ignefusalis. In 1988, neem diminished egg-laying and mine damage by the headminer, H. albipunctella, but no data were available for 1989 because of the low infestation levels of this pest. Neem exhibited some systemic activity. Soil applied neem kernel powder partially protected millet against K. angulifera and C. ignefusalis. Neem treated plots yielded more grain and suffered less damage by insect pests than four different cultural practices. Only the addition of fertilizer was superior to neem in reducing yield losses but it was inferior in limiting pest losses. Experiments to test the residual activity of neem showed that this botanical insecticide can effectively protect millet against K. angulifera for at least seven days, and possibly longer if ultra-violet rays and rainfall are not prevalent. Analysis of plant selection behavior of K. angulifera showed that neem is an antifeedant rather than a repellent. On first to third instar nymphs, growth regulating activity expressed as a difficulty in molting or an absence of sclerotization may occur. Topical applications of neem to the stemborer, C. ignefusalis, also caused growth abnormalities, mostly molting disturbances. Treated larvae that reached the adult stage were malformed. This research indicates that neem based insecticides offer considerable promise for Sahelian farmers for protecting millet crops. It is effective against K. angulifera, but less effective against the stemborer, C. ignefusalis. Although the data obtained for H. albipunctella in 1988 was promising, it was insufficient to reach any conclusions regarding neem's efficacy with respect to this pest.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

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.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Mekonnen, Tadele Tefera, and Tadele Tefera. "Biological control potential of the spotted stem borer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) with the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/16063.

Texto completo

Resumen

Thesis (PhD (Agric))--University of Stellenbosch, 2004. ENGLISH ABSTRACT: Biological control studies were conducted with isolates of entomopathogenic fungi Beauveria bassiana and Metarrhizium anisopliae from Ethiopia and South Africa against the spotted stem borer Chilo partellus. The study was conducted from April 2002 to April 2003, at the department of Entomology and Nematology, University of Stellenbosch, South Africa. The objectives were to screen these isolates for pathogenicity and to determine the susceptibility of different larval instars; to study the effect of temperature on fungal development and virulence; to investigate food consumption of fungus treated larvae; to determine compatibility of fungal isolates with insecticides; to study the effect of exposure methods and diets on larval mortality; and to evaluate promising isolates under greenhouse conditions using artificially infested maize plants. Four isolates of B. bassiana and six isolates of M. anisopliae were tested against second instar larvae. Of these isolates, B. bassiana (BB-01) and M. anisopliae (PPRC-4, PPRC-19, PPRC-61 and EE-01) were found to be highly pathogenic inducing 90 to 100 % mortality seven days after treatment. In subsequent assays, the fungal isolates were tested against third, fourth, fifth and sixth instar larvae. Second and sixth instar larvae were more susceptible to these isolates than third, fourth and fifth instar larvae. Conidial germination, radial growth and sporulation of the isolates PPRC-4, PPRC-19, PPRC-61, EE-01 and BB-01 were retarded at 15 and 35 0C. A suitable temperature range for the isolates was from 20 - 30 0C. At 25 and 30 0C the isolates induced 100 % mortality to second instar larvae within four to six days. Second and third instar C. partellus larvae were treated with the isolates PPRC-4 and BB-01, and daily consumption of maize leaf was measured. Treatment with the fungi was associated with a reduction in mean daily food consumption. In in-vitro studies, five concentrations (0.1 ppm, 1 ppm, 5 ppm, 10 ppm, and 100 ppm active ingredients) of the insecticides benfuracarb and endosulfan were tested with the isolates PPRC-4, PPRC-19, PPRC-16, EE-01 and BB-01. Increasing the concentration of the insecticides adversely affected germination, radial growth and sporulation of the isolates. In in-vivo studies combining the fungi, PPRC-4 and BB-01,with low concentrations (1 and 5 ppm a.i.), of the insecticides increased the mortality of third instar larvae from 65 to 100 %. Larvae sprayed directly with conidia, exposed to conidia treated leaves and dipped into conidial suspensions suffered high mortality of 98 to 100 %. Larvae exposed to treated leaves and larvae sprayed directly with conidia produced high numbers mycoses in cadavers. Exposure of larvae to treated leaves yielded high sporulation. At a low conidial concentration (1.25x107 conidia/ml), mycosis and sporulation were high. The optimum temperature was 20 0C for mycosis and 15 0C for sporulation. In greenhouse trails, a conidial suspension of 2 x 108 conidia/ml of the pathogenic isolates was sprayed on 3 to 4 week-old maize plants infested with 20 second instar larvae per plant. This resulted in suppression of foliar damage. Treatment with the fungi also reduced stem tunneling and deadheart. In addition, fungal treatment increased mean plant fresh and dry biomass compared to untreated control plants. In general, results from laboratory and greenhouse studies indicated that there was good potential for the use of these fungal isolates for controlling C. partellus larvae. AFRIKAANSE OPSOMMING: Biologiese beheerstudies is uitgevoer met isolate van die insekpatogeniese swamme, Beauvaria bassiana en Metarrhizium anisopliae teen die gespikkelde stamboorder, Chilo partellus. Die doelwitte was om hierdie isolate te evalueer vir patogenesiteit; die vatbaarheid van verskillende larvale instars teenoor hulle te bepaal; die invloed van temperatuur op swamontwikkeling en virulensie te bepaal; die voedsel inname van swambehandelde larwes te ondersoek; die verenigbaarheid van die swamisolate met insektedoders te bepaal; die invloed van blootstellingsmetodes en diëte op larvale mortaliteit; en om belowende isolate in glashuisproewe te evalueer met gebruik van kunsmatig besmette mielieplante. Vier isolate van B. bassiana en ses isolate van M. anisopliae is teen tweede instar larwes getoets. Uit dié isolate is B. bassiana (BB-01) en M. anisopliae (PPRC-4, PPRC- 19, PPRC-16 en EE-01) as hoogs patogenies bevind. Hulle het 90 tot 100 % mortaliteit na sewe dae veroorsaak. In daaropvolgende essays, is die swamisolate teen derde, vierde, vyfde en sesde instar larwes getoets. Tweede en sesde instar larwes was gevoeliger vir die isolate as die derde, vierde en vyfde instar larwes. Spoorkeming, radiale groei en sporulasie van die isolate PPRC-4, PPRC-19, PPRC-61, EE-01 en BB-01, is by 15 en 35 0C vertraag. ‘n Aanvaarbare temperatuurreeks vir die isolate is vanaf 20 tot 30 0C. By 25 en 30 0C het die isolate 100 % mortaliteit teen tweede instar larwes binne vier tot ses dae geïndusseer. Tweede en derde instar C. partellus larwes is met die isolate PPRC-4 en BB-01 behandel en die daaglikse inname van mielieblare gemeet. Behandeling met die swamme is met ‘n afname in die gemiddelde voedselinname geassosieer In in-vitro studies is vyf konsentrasies (0.1 dpm, 1 dpm, 5 dpm, 10 dpm en 100 dpm aktiewe bestandele) van die insekdoders, benfuracarb en endosulfan getoets saam met die isolate PPRC-4, PPRC-19, PPRC-16, EE-01 en BB-01. ‘n Toename in die konsentrasie van die insekdoders het ontkieming, radiale groei en sporulasie van die isolate benadeel. In in-vitro studies het die kombinering van die die swamme, PPRC-4 en BB-01, met lae konsentrasies (1 en 5 dpm a.b.) van die insekdoders mortaliteit van derde instar larwes vanaf 65 tot 100 % laat toeneem. Larwes wat direk met spore gespuit is, aan behandelde blare blootgestel is en in spoorsuspensies gedoop is het tot hoë mortaliteit gelei, (98 tot 100 %). Blootstelling aan behandelde blare saam met ‘n lae konidiakonsentrasie, 1.25x106 spore/ml) en ‘n temperatuur van 15 tot 20 0C het tot hoë swammikose en sporulasie in kadawers gelei. In glashuisproewe, is ‘n spoorsuspensies van 2 x 108 spores/ml van die patogeniese isolate op 3 tot 4 weekoud mielieplante wat met 20 tweede instar larwes per plant besmet is gespuit. Dit het blaarskade onderdruk. Behandeling met die swamme het ook stamtonnels en dooiehart verminder. Boonop het swambehandeling die vars- en droë plantbiomassa laat toeneem in vergelyking met die onbehandelde kontrole plante. Oor die algemeen het resultate van laboratorium- en glashuisproewe getoon dat daar goeie potensiaal is vir die gebruik van hierdie swamisolate vir die beheer van C. partellus larwes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

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.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Ceballo, Flor Angel Aquino. "An investigation into why coccidoxenoides peregrinus (timberlake) (hymenoptera:encyrtidae) is an effective biological control agent in Queensland citrus /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16498.pdf.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Madire, Lulama Gracious. "Suitability of the leaf-mining fly, Pseudonapomyza sp. (Diptera: Agromyzidae), for biological control of Tecoma stans L. (Bignoniaceae) in South Africa." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/255.

Texto completo

Resumen

Tecoma stans (L.) Juss. Ex Kunth (Bignoniaceae) also known as yellow bells, has a native distribution from Northern Argentina, central America, Mexico and the Southern USA. In many warm climatic regions of the world, T. stans is commonly planted as an ornamental plant because of its yellow flowers, hence the name yellow bells, and pinnate foliage. As a result, this evergreen shrub has wide distribution in the tropical and subtropical parts of the western hemisphere. As is the case in many other parts of the world, T. stans was introduced into South Africa as an ornamental plant, but escaped cultivation and now invades roadsides, urban open spaces, watercourses, rocky sites in subtropical and tropical areas of five South African provinces; Gauteng, Mpumalanga, Limpopo, KwaZulu-Natal, Eastern Cape and neighboring countries. Tecoma stans has the potential of extending its range because its seeds are easily dispersed by wind. The purpose of this work was to carry out pre-release efficacy studies to determine the host specificity and suitability of Pseudonapomyza sp. (Diptera: Agromyzidae), a leaf-mining fly, as a biological control agent of T. stans. Available information suggests that the fly was brought to South Africa (SA) from Argentina in 2005. In that year a worker collected adult root feeding fleabeetles from T. stans and their eggs by collecting soil around the plants in the Argentinian Province of Jujuy, at San Pedro (24°12’592”S, 64°51’328”W). The soil was brought to the SA quarantine laboratory of the Agricultural Research Council, Plant Protection Research Institute (Weeds Division), Pretoria, and placed in a cage containing T. stans plants for flea-beetle larvae to emerge from the eggs. The Pseudonapomyza sp. flies which emerged from that soil were reared to produce a colony of flies used in the study reported here. The feeding behavior of Pseudonapomyza sp. adults is initiated by females which use their ovipositor to puncture holes in the leaf mesophyll and then they feed on the sap oozing from the holes. Since males have no means of puncturing the leaves, they feed from holes made by females. Eggs are laid singly into the tubular leaf punctures. Soon after hatching, the larva feeds on the leaf mesophyll tissue. As the larva feeds within the leaf it creates mines which eventually coalesce to form large blotches. The damaged leaf area reduces the photosynthetic potential of the plant especially when damaged leaves dry and fall off the plants. The potential of Pseudonapomyza sp. as a biocontrol agent is enhanced by the fact that it has a high level of fecundity and a short life cycle. As a result, its populations can build up rapidly to exert a significant impact on T. stans. Host-specificity tests undertaken on 35 plant species in 12 plant families showed that out of the 35 plant species tested, the fly was able to develop on T. stans only. Although Pseudonapomyza sp. adults fed on T. capensis, a South African indigenous ornamental shrub, no larval mines were observed on this plant. This suggests two possibilities; either females of Pseudonapomyza sp. do not oviposit on T. capensis or oviposition takes place but larvae cannot feed and develop on this plant. These studies indicate that this fly is sufficiently host-specific, and can be released against T. stans without posing any threat to either commercial or indigenous plant species grown in South Africa. Experimental designs simulating high populations of Pseudonapomyza sp. showed that the impact of leaf mining fly on T. stans can cause approximately 56 percent aboveground biomass reduction. Other concurrent studies have also showed that low and high density fly infestations can cause 23 percent and 48 percent belowground biomass reductions, respectively. Based on the available information, it appears that Pseudonapomyza sp. may have the potential to reduce the invasive capacity of T. stans in the affected areas. In order to exert more herbivore pressure on T. stans, it is suggested that agents belonging to other feeding guilds, such as root-, stem- and seed-feeding insects, be considered for release to complement the leaf-feeding of Pseudonapomyza sp. An application to release this fly in SA has been submitted to one of the two regulatory authorities.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Kabir, Nasreen Zahan. "Selection of effective antagonists against Rhizoctonia solani (AG-3), the causal agent of Rhizoctonia disease of potato." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27351.

Texto completo

Resumen

Rhizoctonia solani (AG-3), the causal agent of Rhizoctonia disease of potato, overwinters as sclerotia on potato tubers. To develop a biocontrol strategy based on the prevention of the sclerotial germination, an isolation of microorganisms colonizing sclerotia of infected potato tubers (cultivars Norland, Atlantic and Souris), was conducted. In vitro screening was used to select effective antagonistic fungi against Rhizoctonia solani. Fifty fungal isolates were selected in order to cover all identified genera and potato variety and examined for their ability to inhibit germination of sclerotia which were incubated with the test fungus for 14 days. Twenty-four (24) fungal isolates were retained based on their ability to reduce sclerotial viability by more than 50% as compared with 100% viability of untreated sclerotia. These 24 isolates were further examined for their ability to protect Table beet seedlings against the pathogen in greenhouse soils. Based on their ability to protect Table beet seedlings from Rhizoctonia infections and to increase the number of secondary roots and root length isolates, F2, F11, F132, F158, and F258 were screened and test their efficacy to increase beet seed germination in field soils. (Abstract shortened by UMI.)

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Ordon, Violetta. "Field evaluation of fungal antagonists for the reduction of inoculum of Venturia inaequalis (Cke.) Wint." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21616.

Texto completo

Resumen

The use of a biofungicide on the perfect stage of V. inaequalis on leaf litter is one potential way to reduce the number of fungicides used to control apple scab. The previous in vitro screenings of Quebec mycoflora have shown that several isolates are able to significantly reduce the primary inoculum of the pathogen. Among the screened fungi, P176A and P130A, reduced over 98% of the ascospore production and were as effective as Athelia bombacina. However, because in vitro tests are generally poor predictors of in vivo assays a re-evaluation of the antagonists was done under field conditions. Eight fungal isolates, leaf shredding, and two comparative treatments (A. bombacina, 5% urea) were applied to intact scabbed leaves in October 1994 and 1995. After the treatments, the leaves overwintered on the orchard ground until the next spring. In April, samples of treated leaves were randomly selected and placed in spore traps to collect the ejected ascospores during rainfall. Since the primary inoculum was ejected during a four-month period, antagonism was based upon ratings taken throughout the whole ejection season. To evaluate the effect of incubation conditions on the antagonistic performance we incubated separately, in vitro and in vivo, sterile leaf disks which were artificially inoculated with V. inaequalis and fungal isolates. (Abstract shortened by UMI.)

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Saade, Fabienne Eugenie Joseph. "Evaluation of strains of Bacillus thuringiensis as biological control agents of the adult stages of the carrot weevil, Listronotus oregonensis (Coleoptera:Curculionidae)." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=67541.

Texto completo

Resumen

Strains of Bacillus thuringiensis active against Coleoptera were evaluated for toxicity against the adult stage of the carrot weevil, Listronotus oregonensis. Mortality and frass bioassays using a suitable semi-artificial diet showed strains A30, A429 and BTT to be highly toxic. Mortality persisted after initial exposure to the bacteria with the survivors not resuming normal feeding. Attempts to reisolate B. thuringiensis from the insects revealed B. thuringiensis-like organisms in the gut and in/on other structures. At the midgut pH of the insect (pH 8.0), the crystals of the toxic strains were significantly more soluble in vitro than were crystals of the less toxic strain A311. Proteolytic activation of the crystals with gut extracts yielded a protein band (66-67 kDa) for strains A30 and A429 which was similar to he apparent molecular weight of the toxin protein for BTT. Evidence suggests that the low toxicity of strain A311 might be due, in part, to the absence of the toxic moiety of the $ delta$-endotoxin.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Cournoyer, Michel 1976. "Host selection behavior of the adult parasitoid Microctonus hyperodae Loan (Hymenoptera:Braconidae:Euphorinae) and the egg parasitoid Anaphes victus Huber (Hymenoptera:Mymaridae), parasitoids of the carrot weevil, Listronotus oregonensis LeConte (Coleoptera:Curculionidae)." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80244.

Texto completo

Resumen

The carrot weevil, Listronotus oregonensis LeConte (Coleoptera: Curculionidae), is an important pest of carrot in northeastern North America. The objective of this study was to determine the host selection stimuli used by two L. oregonensis parasitoids: the adult parasitoid Microctonus hyperodae Loan and the egg parasitoid Anaphes victus Huber. In the first chapter, the response of M. hyperodae females to various odor components from potential hosts and host plants was tested with a Y-olfactometer. In the second chapter, the effect of L. oregonensis adult sex, feces and movement on host selection behavior of M. hyperodae females was evaluated by quantifying L. oregonensis adult movement and various M. hyperodae female behaviors in an arena. In the third chapter, the response of A. victus females to different L. oregonensis related odor components was evaluated using a filter paper of which half was moistened with odor components and the other half with water.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Philion, Vincent. "The screening of potential fungal antagonists of pseudothecial formation by the apple scab pathogen : Venturia inaequalis." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22791.

Texto completo

Resumen

In 1992, a research program was initiated to select suitable antagonists against the saprophytic (or winter) phase of the apple scab pathogen, Venturia inaequalis. An improved method for the mass screening of a vast collection of fungi was developed for this purpose. Some of the previously reported criteria such as leaf rheology and overwintering structure production proved unreliable or fastidious and cannot be used for in vitro antagonist selection. The main antagonism selection criterium retained was the in vitro inhibition of ascospore formation. To measure ascospore production, a simplified method of in vitro pseudothecia production was devised. This new method eliminates the need for prior conidia production by using a mycelial suspension and greatly reduces the risks of sterile mating by using a cocktail of Venturia inaequalis strains of different origins. Finally, the production cycle duration was reduced by varying the incubation temperature during the simulated winter. Moreover, a quick and efficient method of ascospore collection was developed. Ascospores were forcibly ejected in a large scale bubbler type apparatus in only one hour. This bubbler can be used for other studies including axenically produced ascospores. This new method compared favourably to the previously reported method and was used to screen a collection of about forty-two fungi. Six proved to significantly reduce the ascospore production of Venturia inaequalis. Two were as effective as Athelia bombacina, a previously reported antagonist of pseudothecia formation and inhibited over 98% of the ascospore production. These new organisms are now available for future field tests. Future selections from a large collection of saprophytes can now be based on a reliable and simple in vitro screening methodology.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Sartini. "The effect of inoculum density, virulency, and carrier systems of phoma sp. on biological control of giant foxtail (setaria faberi hermm.)." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/955092.

Texto completo

Resumen

The effect of spore titer, virulency, and carrier systems on biological control of giant foxtail (Setaria faberi hermm.) with a species of Phoma isolated from this weed wereinvestigated. The lowest concentration of Phoma conidia which significantly affected (lowered) growth of giant foxtail was 1x106 conidia/ml. In conducting Koch's postulates, all but one (FF2) of the Phoma, isolates tested infected giant foxtail. Isolates FF1 and FF9 were the most virulent against giant foxtail. No correlation was apparent between virulency and fungus germination rate. No visible difference occurred with in vitro germination rates of spores incubated upon pea vsr water agar media; nutrient rich vs. nutrient poor media, respectively. These results suggest that Phoma spores already contain sufficient nutrients required for infection of foxtail. A definitive answer as to the effect of carrier system (e.g. surfactant, sticker, spreader, etc.) on efficacy of Phoma to infect foxtail could not be determined from results obtained, based upon statistical analysis of variance (ANOVA) for the single experiment performed. Several of the surfactant treatments (e.g. Silwet 77 and 408) did produce significant biomass losses against foxtail due to the phytotoxicity of the carrier system alone, and not reflective of fungal (Phoma) infection. Inoculation of foxtail plants with a conidial suspension amended with carriers of either Tween 20 (0.05%-0.1%) or methylcellulose (0.1%) should optimize chances for sufficient infection resulting in biological control of this weed. Department of Biology

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

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.

Texto completo

Resumen

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

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Lima, Fernanda Blauth de. "Secretômica de Trichoderma atroviride e Trichoderma harzianum frente a Guignardia e citricarpa, agente etiológico da Pinta Preta dos Citros." reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1141.

Texto completo

Resumen

Os agentes de controle biológico têm recebido grande reconhecimento, e o seu uso tem contribuído como um complemento ou substituição de agroquímicos. No entanto, existem poucos estudos sobre o controle biológico da Pinta Preta dos Citros, causada pelo fungo Guignardia citricarpa, o que impede o seu mercado in natura, além de prejudicar a sua exportação pelo uso intensivo de insumos químicos para controlar este patógeno. Os fungos do gênero Trichoderma são agentes de controle utilizados em todo o mundo contra vários fitopatógenos relevantes. Este estudo visou identificar proteínas extracelulares secretadas por T. atroviride T17 e por T.harzianum T1A, eficazes para o controle de G. citricarpa. Por eletroforese bidimensional (2D) foram obtidos perfis de proteínas secretadas por Trichoderma em meio de glicose (controle) e em meio suplementado com micélio desativado de G. citricarpa. As proteínas foram identificadas por LC-MS/MS mostrando que ambas as espécies secretam proteínas diferentes. Foram identificadas 68 proteínas das 178 diferencialmente expressas por T. harzianum, sendo a maioria relacionada aos mecanismos de biocontrole, mesmo no meio controle. Foi verificado que em contato com o patógeno a expressão de proteínas relacionadas com o metabolismo primário diminui. Por outro lado, Trichoderma atroviride mostrou uma maior expressão de proteínas relacionadas com biocontrole na presença de micélio do patógeno. Nesta espécie identificamos 59 proteínas de 116 diferencialmente expressas, principalmente proteínas relacionadas com a degradação da parede celular: α- manosidase, quitinase, mutanase, glicosidase, endoquitinase e, algumas famílias de glicoside hidrolases. Os resultados indicam que estas espécies apresentam um elevado potencial como agentes de controle de G. citricarpa. Os resultados são pioneiros em detalhar a interação de Trichoderrma com G. citricarpa, por meio da análise do secretoma. Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2016-05-11T14:24:21Z No. of bitstreams: 1 Tese Fernanda Blauth de Lima.pdf: 5347447 bytes, checksum: 314027a9e2af4a7cf6e30be761df9f99 (MD5) Made available in DSpace on 2016-05-11T14:24:21Z (GMT). No. of bitstreams: 1 Tese Fernanda Blauth de Lima.pdf: 5347447 bytes, checksum: 314027a9e2af4a7cf6e30be761df9f99 (MD5) Previous issue date: 2016-05-11 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES. Biological control agents (BCA) have received great recognition, and their use has contributed as a complement or replacement of agrochemicals. However, there are few studies on the biological control of Black spot of citrus, caused by the fungus Guignardia citricarpa, which prevents the market in natura, besides damaging their export by the intensive use of chemical inputs to control this pathogen. Trichoderma fungi are the most applied worldwide BCA against various relevant plant pathogens. The purpose of this study was to identify extracellular proteins secreted by T. atroviride T17 and of T. harzianum T1A, which are effective for the control of G. citricarpa. Bidimensional electrophoresis (2D) allowed obtaining the secreted protein profiles of Trichoderma grown in glucose medium (control) and in medium containing inactivated mycelium of G. citricicarpa. From the 178 differentially expressed proteins by T. harzianum, 68 were identified, most of them related to biocontrol mechanisms, even in the control medium. In the presence of the pathogen, the expression of proteins related to the metabolism decreases. On the other hand, Trichoderma atroviride showed higher expression of proteins related to biocontrol pathogen when grown in the presence of pathogen mycelium, when compared to the control medium. From the 116 differentially expressed proteins, 59 were identified, mainly proteins related to fungi cell wall degradation such as α-mannosidase, chitinase, mutanase, glycosidase, endochitinase and, some families of glycoside hydrolases. The results indicate that these species have a high potential as biocontrol agents of G. citricicarpa. These results are pioneers in to detail the Trichoderrma interaction with G. citricicarpa through the secretome analysis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Smith, Risa Barbara. "Plant size, resource concentration and natural enemies : a comparison of four herbivores in monocultures of brussels sprouts and dicultures of brussels sprouts/peppermint." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30791.

Texto completo

Resumen

This thesis was designed to address three seldom studied aspects of the relationship between herbivores and vegetational diversity. 1. Interactions between vegetational diversity and herbivore mortality due to predation were assessed by experimentally manipulating both the species diversity of plants and the densities of a common generalist predator, the spider Enoplagnatha ovata. 2. The importance of plant size to herbivore densities was examined by quantifying plant size (measured as plant height, width, leaf area and growth rates) and adjusting for it through covariate analysis. 3. Differences in population responses of several species of herbivores to both vegetational diversity and a predator, were compared by concurrently studying four lepidopterans. The main experiment used a two factor design, with two planting treatments and two predator treatments. The planting treatments consisted of plots planted with monocultures of brussels sprouts (Brassica oleraceae) and dicultures of brussels sprouts intercropped with peppermint (Mentha piperita). The natural enemy treatments involved augmentations of E ovata in some plots and untreated controls. Two of the herbivores studied, Plutella xylostella and Pieris rapae are monophagous lepidopterans, specializing on crucifers, while the others, Autographa californica and Mamestra configurata are polyphagous. For two species, P. xylostella and M. configurata responses to augmentations of the spider, E. ovata. were different in monocultures and dicultures. Reduced densities of these two species were found in monoculture plots with added spiders; in dicultures increased densities were found in plots with added spiders. This interaction effect points out that generalist predators can be effective in monocultures. I suggest that the importance of natural enemies in monocultures is often overlooked because only the initial colonization phase is being studied. By augmenting predator populations I was able to simulate densities equivalent to those in more established cropping systems. The increased herbivore densities in dicultures with added spiders might be explained by possible predation by E. ovata on other natural enemies of P. xylostella and M. configurata in dicultures but not in monocultures. Supporting evidence for this interpretation lies in the fact that percent parasitism of P. xylostella by the ichneumonid, Diadegma insulare was lower in plots with added spiders than in control plots. Furthermore, parasitism of P. xylostella by D. insulare increased with host density in diculture plots, but not in monoculture plots. Mamestra configurata was not subject to parasitism in this study, precluding assessment of a similar relationship. No A. californica larvae were found in plots with additional spiders. In contrast, P. rapae larvae were not affected by the experimental treatments. Plant size was a crucial determinant of both herbivore populations and percent parasitism of those herbivores. Most importantly, had plant size not been accounted for, the importance of vegetational diversity to both herbivore densities and percent parasitism would have been overestimated. For example, the incorrect conclusion, that vegetational diversity alone was important in determining the abundance of both of the generalist feeders would have been reached. The greater densities of A. californica in monocultures and M. configurata in dicultures were accounted for by plant size. Without plant size adjustments, percent parasitism of P. xylostella by D. insulare would have been misinterpeted as being greater in monocultures than dicultures. With plant size adjustments, the importance of E. ovata augmentations on lowering percent parasitismwas unmasked. All important interaction effects were discovered only after adjustments for plant size had been made. Despite the low densities of all herbivore species, significant responses to experimental treatments were found in three of the four species studied. Only P.l rapae was unaffected by any of the treatments. However, conclusions based on the feeding ng habits of the herbivores could not be made. The polyphagous feeders were affected by generalist predation as much as the crucifer specialist. Parasitism was found in only two of the species, P. xylostella and A. californica. Of these two species parasitism of the specialist, P. xylostella was affected by both vegetational diversity and generalist predation, whereas parasitism of A. californica was not. My study emphasizes multifaceted interactions between the size and diversity of a primary resource and several trophic levels of consumers. Multifactor models, involving several aspects of a cropping system, are required to uncover the important mechanisms behind variable herbivore responses to vegetational diversity. Land and Food Systems, Faculty of Graduate

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Pests Biological control"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros