Academic literature on the topic 'Heterorhabditis'

AbstractDuring 2002-2004, a survey of entomopathogenic nematodes was conducted for the first time in Iran throughout the three provinces in the north-west of the country. Soil samples were tested for the presence of steinernematid and heterorhabditid nematodes by baiting with Galleria mellonella larvae. Of the 833 soil samples studied 27 were positive for entomopathogenic nematodes (3.2%), with 17 (2.0%) containing Heterorhabditis and ten (1.2%) Steinernema isolates. Morphological and molecular studies were carried out to characterise isolates. The Heterorhabditis isolates were identified as Heterorhabditis bacteriophora and Steinernema as Steinernema carpocapsae, S. bicornutum and S. feltiae. Heterorhabditis bacteriophora was the most common species, which was isolated from 17 sites across the three provinces. Steinernema feltiae was the most common species of Steinernema, which was isolated from eight sites but in only two provinces. Steinernema carpocapsae and S. bicornutum were each isolated from only one site. Steinernema spp. were isolated mainly from orchards and grasslands but Heterorhabditis was isolated mainly from grasslands and alfalfa fields.

Abstract A survey for entomopathogenic nematodes (EPN) was carried out in the Arasbaran forests and rangelands, East Azarbaijan province, north-west Iran, during 2006 to 2008. A total of 691 soil samples were collected from 62 localities across the region of which 21 samples (3%) were positive for EPN, including nine samples (1.3%) with heterorhabditids and 12 (1.7%) with steinernematids. Seven isolates (four Steinernema and three Heterorhabditis) were recovered from rangelands and 14 (eight Steinernema and six Heterorhabditis) from forest soil samples. Based on morphology and molecular studies, the Heterorhabditis isolates were identified as H. bacteriophora and the Steinernema isolates as S. carpocapsae, S. bicornutum, S. feltiae, S. glaseri, S. kraussei and three undescribed species referred to here as Steinernema sp. IRAZ7, Steinernema sp. IRAZ13 and Steinernema sp. IRAZ21. Heterorhabditis bacteriophora, the most common species, was present in nine soil samples collected across the forests and rangelands, and of the Steinernema species, S. bicornutum was obtained from three samples, the other species being found from only one or two samples.

AbstractSoil samples from 79 sites on five islands of Indonesia were baited with insects for the recovery of entomopathogenic nematodes. Heterorhabditis and Steinernema were equally prevalent, and were recovered from 11.7% of samples representing 20.3% of sites sampled. Both genera were recovered from coastal sites only. Entomopathogenic nematodes were more prevalent on the Moluccan islands of Ambon and Seram than on Java or Bali. They were not detected on Sulawesi, where non-coastal sites only were sampled. RFLP analysis was used in the identification of nematode isolates. Heterorhabditis indica was the only heterorhabditid identified. Two RFLP types ofSteinernema were identified.

AbstractSoil sampling was conducted within Peninsular Malaysia with the aim of recovering entomopathogenic nematodes (Steinernematidae and Heterorhabditidae). Extensive sampling was performed in the Cameron Highlands, which are climatically distinct from the lowlands, and characterized by lower temperature and humidity. The major areas sampled in the lowlands were at the campus of Universiti Pertanian Malaysia (orchards and plantations), Puchong (secondary rainforest) and along the east coast of the country. Entomopathogenic nematodes were recovered using the Galleria mellonella baiting method. Nematodes were recovered from 10% of the 425 samples assayed. Identifications, using a PCR method, revealed that the 21 identified steinernematids belonged to two different genetic types and that four out of the five heterorhabditids were Heterorhabditis indicus, the remaining heterorhabditid being a new species. The nematodes are currently being screened to evaluate their biocontrol potential for use in Malaysia against foliage-feeding lepidopteran pests of crucifers.

Abstract Targeted surveys were conducted for the entomopathogenic nematode Heterorhabditis in areas of Denmark, Estonia and Hungary. Isolates were identified by IEF, PCR and cross-fertility tests as belonging to three distinct taxonomic groups: H. bacteriophora, the north-west European (NWE) type of H. megidis and the Irish type of Heterorhabditis. The Irish and NWE types of Heterorhabditis were both present in Denmark (at six and four sites, respectively), while only the NWE type was recovered in Estonia. H. bacteriophora was the dominant heterorhabditid identified in Hungary (ten sites), but the Irish type was also detected at two sites. This is the first report of the Irish type of Heterorhabditis on continental Europe. Co-occurrence of two Heterorhabditis types at a single site was noted in Denmark (Irish and NWE) and in Hungary (Irish and H. bacteriophora). Heterorhabditis was recovered at 38.5% of sites (n = 26) in Denmark (north coast of Sjaelland), 27.3% of the coastal sites (n = 22) in Estonia, and 32.6% of sites (n = 46) in Hungary. Isolation et caracterisation d'especes d'Heterorhabditis (Nematoda: Heterorhabditidae) originaires de Hongrie, d'Estonie et du Danemark - Des prospections ciblees ont ete effectuees dans certaines regions du Danemark, d'Estonie et de Hongrie pour rechercher les nematodes du genre Heterorhabditis. Les souches, identifiees par les methodes de concentration isoelectrique, de PCR et d'hybridation, appartiennent aux trois groupes taxinomiques d'Heterorhabditis : H. bacteriophora, le groupe de l'Europe du nord-ouest (NWE) de H. megidis et le groupe irlandais d'Heterorhabditis. Le groupe irlandais et le groupe NWE sont tous les deux presents au Danemark (dans six et quatre sites, respectivement), mais seul le dernier groupe a ete rencontre en Estonie. H. bacteriophora, present dans dix sites, est l'espece dominante d'Heterorhabditis en Hongrie, mais le groupe irlandais a ete egalement detecte dans deux sites. C'est la premiere fois que le groupe irlandais est rencontre en Europe continentale. La presence simultanee de deux types d'Heterorhabditis est signalee au Danemark (groupe irlandais et groupe NWE) et en Hongrie (groupe irlandais et H. bacteriophora). Des Heterorhabditis ont ete collectes sur 38.5% des 26 sites du Danemark (cote nord de Sjaelland), 27.3% des 22 sites du littoral estonien et 32.6% des 46 sites de Hongrie.

Entomopathogenic nematodes (EPN) are useful biological control agents of insect pests. However, the infective juvenile (IJ) stage which is the only stage to occur outside the host is susceptible to environmental extremes such as desiccation. We have isolated desiccation-tolerant strains of the EPN Heterorhabditis megidis. In this paper we describe the surface properties of these desiccation-tolerant mutants. Heterorhabditid IJs retain the sheath of the previous larval stage. The mutant lines possess alterations in the surface properties of the sheath. Differences were observed in fluorescent lipid analogue insertion into the surface of the sheath. Furthermore, cationized ferritin-binding studies demonstrated that the mutant lines possessed an increase in net negative surface charge. Removal of the surface layer of the sheath resulted in the loss of the mutant phenotype and in a reduction in the desiccation tolerance of the parental strain. Therefore, the negatively charged ‘surface coat’ appears to play an important role in the desiccation tolerance of Heterorhabditis species.

Entomopathogenic nematodes (EPNs) are used in biological control of soil insects and show promise in the control of D. speciosa. The objective of this work was to evaluate the potential of native and exotic entomopathogenic nematode isolates in the control of D. speciosa under laboratory and greenhouse conditions. Results showed that all of EPNs caused larval mortality. The most virulent were Heterorhabditis sp. RSC01 (94%), Steinernema glaseri (84%), Heterorhabditis sp. JPM04 (82%) and Heterorhabditis amazonensis RSC05 (78%). There was no effect of the Heterorhabditis sp. RSC01 and S. glaseri isolates on eggs. The maximum mortality of D. speciosa larvae by Heterorhabditis sp. RSC01 was observed at a concentration of 300 IJ/ insect, while by S. glaseri observed the highest mortality at the concentration of 200 IJ/ insect. The Heterorhabditis sp. RSC01 isolate caused over 80% pupal mortality at a concentration of 250 IJ/insect. The virulence of Heterorhabditis sp. RSC01 and S. glaseri was affected by temperature. The Heterorhabditis sp. RSC01 isolate caused reduction in larva survival under greenhouse conditions at all of the tested concentrations and there was no difference in mortality among different concentrations of infectid juveniles.

Soil samples from 100 cultivated and natural sites were assessed for the presence of entomopathogenic nematodes. Heterorhabditid nematodes were recovered from three soil samples during spring months, with the overall positive sample rate of 3%. The isolates of entomopathogenic nematodes were identified as three different strains conspecific with Heterorhabditis bacteriophora (Heterorhabditidae). They were found from natural sites and vineyard, while no recovery occurred from intensively cultivated agricultural fields. The morphometrical characteristics of infective juveniles and males showed differences between all Croatian strains and from the original description. Heterorhabditis bacteriophora ISO9 was bioassayed on Lasioptera rubi (Cecidomyiidae) (the raspberry gall midge) larvae at different nematode concentrations under laboratory conditions. The significantly highest mortality was observed in treatments with 50 and 200 infective juveniles per insect larvae within 8 days after inoculation. This is the first report of entomopathogenic nematodes of the family Heterorhabditidae from Croatia, and susceptibility of L. rubi larvae to entomopathogenic nematodes. The Croatian strain H. bacteriophora ISO9 was proved to possess strong insecticidal properties against L. rubi larvae.

RESUMO A cochonilha-da-raiz-do-cafeeiro Dysmicoccus texensis (Tinsley) ataca as raízes desta planta, podendo causar sérios danos às plantações e conseqüentes perdas na produção. Os nematóides entomopatogênicos (NEPs) são agentes eficientes no controle de várias pragas encontradas no solo, o que sugere provável eficiência no controle da cochonilha-da-raiz-do-cafeeiro. Dessa forma, este trabalho teve por objetivo avaliar a patogenicidade de alguns isolados de NEPs à cochonilhada-raíz-do-cafeeiro através de testes de seleção de isolados, determinação da concentração letal máxima (CLM99) e patogenicidade a criptas coletadas no campo. Os isolados Heterorhabditis sp. CCA, Heterorhabditis bacteriophora, Heterorhabditis sp. JPM3.1 e Heterorhabditis sp. JPM3 foram os que apresentaram maior virulência, alcançando valores máximos de mortalidade de 100, 94, 94 e 82%, respectivamente, na maior concentração testada (100 juvenis infectantes (JI)/inseto). A CL99 determinada para Heterorhabditis sp. CCA foi estimada em 530 JI/placa. Valor semelhante foi encontrado para Heterorhabditis sp. JPM3 que teve a CL99 igual a 560 JI/placa. Estimando a concentração por área, o valor obtido para Heterorhabditis sp. CCA e Heterorhabditis sp. JPM3 foi de 28 e 29 JI/cm2, respectivamente. No teste realizado com criptas, ambos os isolados de NEPs foram patogênicos aos insetos.

Attack by the coffee berry borer Hypothenemus hampei causes significant damage to coffee crops because it affects the quality of the coffee fruit during different developmental stages, which results in production losses. Control of the borer is difficult owing to its cryptic behavior and the fact that it spends its entire life cycle inside the coffee berries. This makes it difficult for natural enemies to reach it, as well as for it to come into contact with chemical insecticides. The objective of the present study was to select and evaluate the virulence of entomopathogenic nematodes (EPNs) on the coffee berry borer H. hampei and their compatibility with the insecticide cyantraniliprole under laboratory conditions. Initially, the pathogenicity and virulence of 16 isolates of Steinernema and Heterorhabditis towards coffee berry borer larvae and adults were evaluated. The most virulent isolates to both larvae and adults were determined by topical inoculation tests in coffee fruits (berries) infested by the insect, using a concentration of 100 infective juveniles (IJs)/fruit. The same isolates were also evaluated for viability and infectivity when combined with cyantraniliprole. The isolates S. feltiae (IBCB-n 47) and Heterorhabditis amazonensis (GL) displayed the highest virulence towards adults (54%). For larvae, we observed a high virulence of S. feltiae, Heterorhabditis amazonensis, Heterorhabditis indica, Heterorhabditis sp. (JPM4), Heterorhabditis sp. (NEPET 11), Heterorhabditis sp. (IBCB-n 46), and Heterorhabditis sp. (IBCB-n 44) that promoted 100% mortality. Regarding the topical inoculation test on infested fruits, S. feltiae and Heterorhabditis sp. (IBCB-n 46) were unable to penetrate the fruit through the hole made by the borer, infect, and cause the death of insects. Cyantraniliprole formulation affected the viability of IJs of S. feltiae and Heterorhabditis sp. (IBCB-n 46), mainly after 48 h of exposure.

Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The agricultural industry in South Africa is dominated by the use of insecticides. Producers rely heavily on chemicals that cause increased risk to health, the environment and ecology, rapid resistance development in key insect pests and pesticide residues on crops. The increased concern regarding the impact of these pest management practices on the environment and alternative pest management strategies are being investigated. Entomopathogenic nematodes (EPNs) have been identified as being promising biological control agents of key insect pests. The two EPN genera that have shown promise for use as biological control agents within an integrated pest management programme areSteinernema and Heterorhabditis. Commercialisation and the successful use of EPNs to control pests in North America, Australia, Europe and Asia have confirmed the effectiveness of these organisms as biological control agents. Unfortunately, EPNs in large enough numbers for commercial field applications are not yet available on the South African market. Large numbers of EPNs can be produced through either in vivo or in vitro culturing practices. The objective of this study was to streamline the in vivo production process by using two endemic EPN species, Heterorhabditis zealandica (SF41) and H. bacteriophora (SF351). These EPN isolates have been shown to be effective control agents of codling moth Cydia pomonella, false codling moth Thaumatotibia leucotreta, obscure mealybug Pseudococcus viburni, and the banded fruit weevil Phlyctinus callosus. A comparative study was conducted to identify suitable host insects for EPN production of local H. zealandica (SF41) and H. bacteriophora (SF351) strains. Hosts were selected according to their susceptibility to the two EPN species used, their general availability and the ease and cost of rearing. Wax moth larvae Galleria mellonella (WML) and mealworms Tenebrio molitor (MW) were selected as hosts. In order to produce nematodes of consistent quality, a continuous source of host insects reared on a standardised diet was required. WML and MW were each reared on five different diets in the dark at ±26°C. A superior diet for each host was selected according to the diet that produced, on average, the larvae with the highest body mass within a specific timeframe. The heaviest WML, at an average weight of 0.19 g per larva, were produced on a diet consisting of 118 g wheat flour, 206 g wheat bran, 118 g milk powder, 88 g brewer‟s yeast, 24 g wax powder, 175 ml honey and 175 ml glycerol. The heaviest MW larvae weighed, on average, 0.0154 g per larva, and were produced on a diet consisting of 100% wheat bran. To confirm the hypothesis that a linear relationship exists between the weight of a host and the number of nematodes produced from that host, a study was conducted to determine the number of H. zealandica and H. bacteriophora produced per g of host. WML, MW, codling moth larvae and false codling moth larvae were weighed individually and inoculated with the two nematode species respectively. In addition, nematode production in frozen MW and WML was tested. The number of nematodes harvested from each host was counted, and the average number of nematode progeny produced in each host was calculated. A significant linear correlation between the weight of WML and MW and the number of H. zealandica and H. bacteriophora respectively produced confirmed the hypothesis that nematode production within the specified host increases with an increase in host weight. WML produced the highest number of H. zealandica and H. bacteriophora per g of host (1 459 205 ± 113 670 and 1 898 512 ± 94 355), followed by MW larvae (836 690 ± 121 252 and 414 566 ± 67 017). Lower numbers of H. zealandica and H. bacteriophora per g codling moth (57 582 ± 10 026 and 39 653 ± 8 276) and per g false codling moth (192 867 ± 13 488 and 97 652 ± 23 404) were produced. Successful infection of a suitable insect host is one of the key factors in an efficient in vivo nematode production process. Three inoculation techniques were compared using H. zealandica and H. bacteriophora: inoculation with a pipette; shaking of hosts in the nematode inoculum; and immersion of hosts in the nematode suspension. With each inoculation technique, WML and MW were used as host larvae and were inoculated with nematodes at a concentration of 200 infective juveniles (IJs) / larva. The percentage mortality of insect hosts was determined after two days, and EPN infectivity, confirmed by colour change and dissection, after seven days. The highest percentage EPN infection was obtained using pipetting for both nematode isolates and hosts. Nematode infection rates for all nematode-host combinations obtained with pipetting were above 90%, with the exception of MW inoculation with H. bacteriophora, where the percentage of infection obtained was 76%. The current study conclusively demonstrated that variations in infection levels occur, depending on the inoculation technique used. In an additional effort to enhance infectivity during inoculation, H. zealandica, H. bacteriophora and MW were subjected to host-stressor regimes and to nematode- infectivity-enhancing additives. Three treatments, plus a control treatment, were compared. Exposing MW to 70°C tap water prior to inoculation did not increase infection levels. On the contrary, reduced infection levels were observed with host immersion in 70°C tap water followed by inoculation with H. bacteriophora, compared to the control. Only 12% infection was obtained compared to the 48% infection achieved in the control. Infection obtained using H. zealandica was 21%. Treating H. zealandica and H. bacteriophora IJs withMn2+SO4.H20 in a suspension, prior to inoculating MW, did not significantly enhance nematode virulence. Inoculation of MW with treated H. zealandica IJs led to an infection rate of 81%, compared to the control, with which 80% infection rate was obtained. Heterorhabditis bacteriophora caused 47% MW infection, compared to the control, which was subject to 48% infection. A combination of the two above-mentioned treatments did not enhance the infection levels either. Immersing MW into 70°C tap water prior to inoculation with nematodes treated with Mn2+SO4.H20 led to infection levels of 13% and 9% respectively when H. bacteriophora and H. zealandica were used. Future research is required to optimise the protocol used in this study of subjecting MW and local nematode isolates to stressor regimes. The ability of two formulations to maintain biological activity and virulence of H. zealandica was investigated. A quality standard control measure was used to measure the percentage survival and virulence of formulated H. zealandica over a period of 21 days. IJs were formulated into Pesta granules and coconut fibres, while nematodes stored in tap water served as the control. The numbers of live H. zealandica in Pesta granules and coconut fibres decreased drastically after seven days of storage. The survival of nematodes in Pesta granules dropped to 9.79% after 21 days compared to the control, where the survival rate was 79.79%. Nematode survival in coconut fibres was even lower, at 25.84% after seven days and 2.25% after 21 days. After 21 days in storage, 100%+of nematodes survived in the control for coconut fibres. The application of the standard quality control measure, which was used to determine the virulence of formulated H. zealandica, proved to be ineffective. Higher MW mortality rates were obtained in the control where no nematodes were added to larvae, compared to where nematodes were added in varying dosages. However, adjusting certain aspects in the protocol of this quality control measure specifically to accommodate local conditions could possibly make it a more effective tool for measuring endemic nematode virulence.
AFRIKAANSE OPSOMMING: Die landboubedryf in Suid-Afrika word oorheers deur die gebruik van insekdoders. Vervaardigers steun swaar op chemikalieë wat toenemend gesondheids-, omgewings- en ekologiese risiko's, asook die snelle ontwikkeling van weerstand in sleutelinsekteplae veroorsaak, en wat reste van plaagdoders op gewasse laat. Na aanleiding van toenemende besorgdheid oor die impak van hierdie plaagbestuurspraktyke op die omgewing, word alternatiewe plaagbestuurstrategieë ondersoek. Entomopatogeniese nematodes (EPNs) is geïdentifiseer as belowende biologiese beheeragente van sleutelinsekteplae. Die twee EPN genera wat belofte inhou vir gebruik as biologiese beheeragente binne 'n geïntegreerde plaagbestuursprogram is Steinernema en Heterorhabditis. Kommersialisering en die geslaagde gebruik van EPNs om insekplae te beheer in Noord-Amerika, Australië, Europa en Asië, het die doeltreffendheid van hierdie organismes as biologiese beheeragente bevestig. Ongelukkig is EPNs in groot genoeg getalle vir kommersiële aanwending in die veld nog nie op die Suid-Afrikaanse mark beskikbaar nie. Groot getalle EPNs kan deur in vivo en in vitro teling verkry word. Die doelwit van hierdie studie was om die in vivo produksieproses te stroomlyn deur die gebruik van twee endemiese EPN spesies, Heterorhabditis zealandica (SF41) en H. bacteriophora (SF351). Hierdie EPN isolate is deur navorsing bewys om doeltreffende beheeragente van kodlingmot Cydia pomonella, vals kodlingmot Thaumatotibia leucotreta, ligrooswitluis Pseudococcus viburni, en gebande vrugtekalanders Phlyctinus callosus te wees. 'n Vergelykende studie is gedoen om geskikte gasheerinsekte vir EPN produksie van plaaslike H. zealandica (SF41) en H. bacteriophora (SF351) isolate te vind. Gashere is geselekteer op grond van vatbaarheid vir die EPN spesie wat gebruik word, en algemene beskikbaarheid en gemak en koste van teling. Wasmotlarwes Galleria mellonella (WML) en meelwurms Tenebrio molitor (MW) is as gashere gekies. Ten einde nematodes van konsekwente kwaliteit te teel, word 'n deurlopende bron van gasheerinsekte benodig wat op 'n gestandaardiseerde dieet voed. WML en MW is onderskeidelik op vyf verskillende diëte geteel by ±26°C in die donker. Die beste dieet vir elke gasheer is gekies op grond van die dieet wat, gemiddeld, die swaarste larwes binne 'n spesifieke tydsraamwerk opgelewer het. Die swaarste WML, teen 'n gemiddelde massa van 0.19 g per larwe, is geteel op 'n dieet wat bestaan het uit 118 g koringmeel, 206 g semels, 118 g melkpoeier, 88 g brouersgis, 24 g verpoeierde was, 175 ml heuning en 175 ml gliserol. Die swaarste MW larwes het gemiddeld 0.0154 g per larwe geweeg en is geteel op 'n dieet van 100% semels. Ten einde die hipotese te bevestig dat 'n lineêre verwantskap bestaan tussen die massa van 'n insekgasheer en die aantal nematodes wat deur daardie gasheer geproduseer word, is 'n studie gedoen om die aantal H. zealandica en H. bacteriophora per gasheergram te bepaal. WML, MW, kodlingmotlarwes en vals kodlingmotlarwes is individueel geweeg en met infektiewe larwes van die twee onderskeidelike EPN spesies geïnokuleer. Daarbenewens is die vermeerdering van nematodes in bevrore MW en WML ook getoets. Die aantal nematodes wat in elke gasheer geoes is, is getel, en die gemiddelde nematode-afstammelinge in elke gasheer bereken. 'n Beduidende lineêre korrelasie tussen die massa van WML en MW en die aantal H. zealandica en H. bacteriophora wat onderskeidelik geproduseer is, het die hipotese bevestig dat nematode-vermeerdering binne hierdie gashere toeneem namate die gasheermassa toeneem. WML het die meeste H. zealandica en H. bacteriophera per gasheergram opgelewer (1 459 205± 113 670 en 1 898 512± 94 355 onderskeidelik), gevolg deur MW larwes (836 690± 121 252 en 414 566± 67 017 onderskeidelik). Laer getalle H. zealandica and H. bacteriophora per gram kodlingmot (57 582 ± 10 026 en 39 653 ± 8 276) en per gram vals kodlingmot (192 867 ± 13 488 en 97 652 ± 23 404) is egter geproduseer. Een van die sleutelfaktore vir die doeltreffendheid van die in vivo vermeerdering van nematodes is geslaagde gasheerinfeksie. Drie inokulasietegnieke is dus geëvalueer en vergelyk deur H. zealandica en H. bacteriophora te gebruik: inokulasie met 'n pipet, skud van gashere in 'n nematode-inokulum, en gasheerindompeling in 'n nematode-suspensie. WML en MW is as gashere gebruik vir elke inokulasietegniek, en is geïnokuleer met nematodes wat uit 'n konsentrasie van 200 infektiewe larwes (ILs) / insek larwe bestaan het. Die persentasie dooie insekgashere is na twee dae bepaal, en infeksie soos bevestig deur kleurverandering en disseksie, na sewe dae. Die hoogste persentasie infeksie deur sowel nematode-isolate as gashere te gebruik, was met die pipet-tegniek. Die infeksiekoerse vir alle nematode-gasheerkombinasies met die pipet-tegniek was hoër as 90%, met die uitsondering van MW-inokulasie met H. bacteriophora, waar die infeksie 76% was. Hierdie studie toon dat afwykings voorkom in die mate van gasheerinfeksie, na gelang van die inokulasietegniek wat gebruik is. In 'n bykomende poging om infeksie na inokulasie te verhoog, is H. zealandica, H. bacteriophora en MW onderwerp aan stressors en bymiddels om nematode-infeksie te bevorder. Drie behandelings, asook 'n kontrole-behandeling, is vergelyk. Infeksievlakke het nie verhoog deur MW voor inokulasie aan kraanwater van 70°C bloot te stel nie. Inteendeel, laer infeksievlakke is opgemerk waar gashere in kraanwater van 70°C gedompel is en daarna met H. bacteriophora geïnokuleer is, vergelyke met die kontrole. Gasheerinfeksie van slegs 12% is verkry, vergelyke met 48% in die kontrole. Infeksie van 21% is met H. zealandica verkry. Die virulensie van nematodes het nie beduidend toegeneem deur H. zealandica en H. bacteriophora IL in 'n suspensie met Mn2+SO4H20 te behandel voor MW geïnokuleer is nie. Inokulasie van MW met behandelde H. zealandica IL het tot 'n infeksie van 81% gelei, vergelyke met die kontrole waar 'n infeksie van 80% behaal is. H. bacteriophora het 'n MW-infeksie van 47% veroorsaak, vergelyke met die kontrole se infeksiekoers van 48%. 'n Kombinasie van die twee bogenoemde behandelings het eweneens nie gasheerinfeksievlakke verhoog nie. Die indompeling van meelwurms in kraanwater van 70°C voor inokulasie met nematodes wat met Mn2+SO4H20 behandel is, het tot gasheerinfeksie van 13% en 9% onderskeidelik gelei wanneer H. bacteriophora en H. zealandica gebruik is. Toekomstige navorsing is nodig om die protokol te verbeter wat in hierdie studie gebruik is om MW en plaaslike nematode-isolate aan stressors te onderwerp. 'n Ondersoek is gedoen na die vermoë van twee formulasies om biologiese aktiwiteit en virulensie van H. zealandica te onderhou. 'n Kwaliteitsstandaardtegniekis gebruik om weekliks die persentasie oorlewing en virulensie van geformuleerde H. zealandica oor 'n tydperk van 21 dae te meet. IL is in Pesta korrels en klappervesel geformuleer, terwyl nematodes in kraanwater gedien het as kontrole. Die aantal lewende H. zealandica in Pesta korrels en klappervesel het drasties verminder na sewe dae in die formulasie. Oorlewing van nematodes in Pesta korrels het gedaal tot 9.79% na 21 dae vergyleke met die kontrole, waar 79.79% oorleef het. Nog minder nematodes - 25.84% - het na sewe dae in die klappervesel oorleef, en slegs 2.25% na 21 dae. Na 21 dae van berging het 100%+ van nematodes oorleef in die kontrole vir klappervesel. Die toepassing van die kwaliteitsstandaardtegniek om die virulensie van geformuleerde H. zealandica te bepaal, het ondoeltreffend geblyk. Verhoogde MW sterftesyfers is verkry in die kontrole waar geen nematodes by die inseklarwes gevoeg is nie, vergelyke met die byvoeging van hoër dosisse nematodes. Nietemin, die aanpassing van sekere aspekte in die protokol van hierdie kwaliteitsbeheermeting om spesifiek plaaslike toestande in ag te neem, sou dit moontlik 'n meer doeltreffende middel kon maak om die virulensie van endemiese nematodes te bepaal.

Heterorhabditis é um gênero de nematoides entomopatogênicos, simbiontes de bactérias do gênero Photorhabdus. Juntos, infectam e matam artrópodes. A linhagem LPP7 de H. baujardi foi isolada na cidade de Monte Negro (RO). A vitelogênese compreende o acúmulo de reservas dentro do ovócito em crescimento. A vitelogenina é uma lipoproteína transportadora de lipídeos para o ovócito, formando o vitelo. Sequenciamos um fragmento de 800pb do gene vit-6 de LPP7, codificante do fim do polipeptídeo homólogo ao VT3 de O. tipulae ou ao YP88 de C. elegans. Seu transcrito possui 61% de identidade com VIT-6 de O. tipulae CEW1 e 46% de identidade com VIT-6 de C. elegans. As vitelogeninas purificadas de LPP7 mostram três bandas com pesos moleculares próximos às vitelogeninas de O. tipulae (VT1, VT2 e VT3). Mas, ao contrário do que foi mostrado em O. tipulae, onde a banda VT1 é apresenta um polipeptídeo, VT1 de LPP7 aparentemente contém um par de bandas com massas moleculares quase idênticas, como ocorre com a proteína YP170 de C. elegans.
Heterorhabditis is a genus of entomopathogenic nematodes that are associated with bacteria of the genus Photorhabdus. Together, they infect and kill arthropods. Heterorhabditis baujardi strain LPP7 was isolated in Monte Negro (RO). The yolk reserves are transported to the growing oocyte by a lipoprotein called vitellogenin. We have cloned and partially sequenced a fragment of 800pb of the vit-6 gene from LPP7. This fragment contains a portion of a homologous to those coding for the vitellins VT3 of O. tipulae and the YP88 C. elegans polypeptides. The polypeptide coded by the sequenced fragment showed that it has 61% identity to VIT-6 protein of O. tipulae CEW1 and 46% of identity to VIT-6 of C. elegans. The purified proteins of LPP7 show three bands with migrations close to the vitellins of O. tipulae (VT1, VT2 and VT3). However, unlike what was shown in O. tipulae where the VT1 band is comprised of a single polypeptide, LPP7 VT1 apparently contains a pair of bands with almost identical molecular masses as occurs with the homologous vitellin of C. elegans YP170.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The black weevil (Cosmopolites sordidus) is the main pest of banana crops in several regions of the world, causing significant losses in productivity of the culture. The larvae build galleries in the rhizome or pseudostem base, affecting the development of the plant and the fruits, beside favoring the installation of pathogenic microrganisms. The use of nematodes to control of the pest can be an alternative, mainly because the insect's habits make them a potential target of entomopathogenic nematodes. So, this study had the objectives to evaluate isolates of entomopathogenic nematodes in laboratory conditions to their use in controlling the borer. Sixteen isolates Sterinernematidae and Heterorhabditidae were tested, applied on pseudostem (100JIs/cm2). The evaluation was performed 7 days after application. After, the most virulent isolates were compared with each other for production of nematodes in cadavers of wax moth (Galleria mellonella) and also about his compatibility with the insecticide carbofuran. All isolates were pathogenic to the adults of C. sordidus, except the isolate SC (Steinernema carpocapsae). The most virulent isolates were CB24 and CB40 (both of the Heterorhabditidae), which caused respectively 33,3% and 36,7% of mortality. The two isolates showed high production of JIs. The insecticide was compatible with isolated CB40 and incompatible with CB24, nevertheless, CB24 showed better performance in combination with carbofuran
A broca-da-bananeira (Cosmopolites sordidus) é a principal praga dos cultivos de banana em várias regiões do mundo, acarretando perdas significativas na produtividade da cultura. As larvas constroem galerias no rizoma ou base do pseudocaule, afetando o desenvolvimento da planta e dos frutos, além de favorecer a instalação de microrganismos patogênicos. O uso de nematóides para o controle da praga pode ser uma alternativa, principalmente devido aos hábitos do inseto que os tornam um potencial alvo dos nematóides entomopatogênicos. Assim, este trabalho teve como objetivos avaliar isolados de nematóides entomopatogênicos em condições de laboratório visando sua utilização no controle da broca. Foram testados 16 isolados pertencentes às famílias Sterinernematidae e Heterorhabditidae, aplicados sobre pseudocaule (100JIs/cm2). A avaliação foi realizada 7 dias após a aplicação. Os isolados mais eficientes foram comparados entre si quanto à produção de nematóides em cadáveres da traça dos favos (Galleria mellonella) e também quanto a sua compatibilidade com o inseticida carbofurano. Todos os experimentos foram realizados em delineamento inteiramente casualizado. Verificou-se que exceto o isolado SC (Steinernema carpocapsae), todos os demais foram patogênicos aos adultos de C. sordidus. Os isolados mais virulentos foram o CB24 e CB40, os quais provocaram respectivamente 33,3% e 36,7% de mortalidade, ambos da família Heterorhabditidae. Os dois isolados apresentaram alta produção de JIs, não diferindo estatisticamente entre si. O inseticida foi compatível com o isolado CB40 e incompatível com CB24, mesmo assim, CB24 apresentou melhor desempenho em associação com carbofurano

The biological control of subterranean termites (Isoptera: Rhinotermitidae; Termitidae) using entomopathogenic nematodes (Nematoda: Steinernematidae; Heterorhabditidae) (EPN) was investigated. The desert subterranean termite Heterotermes aureus Snyder was found to be very susceptible to Steinernema riobrave Cabanillas, Poinar and Raulston. In laboratory bioassays S. riobrave (355, TP, 3-8b and 7-12 strains), S. carpocapsae Weiser (Mexican 33 strain), S. feltiae Filipjev (UK76 strain), and Heterorhabditis bacteriophora Poinar (HP88 strain) were all capable of infecting and killing H. aureus, Reticulitermes flavipes Kollar, R. virginicus Banks, Coptotermes formosanus Shiraki and Gnathamitermes perplexus Banks. In sand assays, S. riobrave caused > 90% H. aureus mortality in 3 days and 100% mortality by day 5 at 22 °C. TP strain of S. riobrave caused 75% R. flavipes mortality and 90.91% C. formosanus mortality in 7 days. EPNs utilizing termites as hosts produced smaller sized offspring, with the exception of S. feltiae. Stunted females of S. feltiae were frequently found in termite cadavers, but no progeny. Small IJs of S. carpocapsae, S. riobrave and H. bacteriophora infect, reproduce and form normal size IJs after subsequent infection in Galleria mellonella L. The progeny of small IJs were as effective as the normal size IJs, with regard to subsequent induced mortality, under the conditions tested. In laboratory two-container choice experiments, H. aureus were repelled by EPN treated areas for up to 10 days at 10,000 IJs per device. The repellency threshold was found to vary among nematodes species. We hypothesis that it is the physical movement of the nematodes that repels the termites. Temperature is a key factor affecting nematode pathogenicity. Temperature tolerance of the nematodes varied between species. After a gradual heat adaptation process, S. riobrave and H. bacteriophora caused significantly higher H. aureus mortality at 32 °C compared with original laboratory cultured strains. Further work may result in the contribution of commercially available strains with enhanced heat tolerance. Preliminary field studies confirmed EPN protection of a structure, however, termites began to reinfest 4 weeks after the application. Additional tests are necessary to provide more evidence before we can conclude nematodes as useful in the field.

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As cigarrinhas do gênero Mahanarva causam danos às culturas da família Poaceae, como braquiária, capim-elefante e cana-de-açúcar, em função da sucção de seiva das raízes (fase imatura) e folhas (fase adulta). Com a crescente demanda de redução do uso de inseticidas químicos para o controle de insetos praga, surge a necessidade do desenvolvimento de novos métodos de controle. Nesse cenário, o controle biológico recebe destaque e no caso das cigarrinhas, os nematóides entomopatogênicos (NEPs) são potenciais agentes de controle, pois exploram a superfície do solo, mesmo ambiente da praga enquanto esta se alimenta nas raízes. Portanto, com o objetivo de conhecer a ação de NEPs e selecionar isolados desses patógenos contra a cigarrinha-das-pastagens, Mahanarva spectabilis, e a cigarrinha-dasraízes, Mahanarva fimbriolata, experimentos foram desenvolvidos com diversos isolados de NEPs sobre diferentes fases de desenvolvimento do inseto. Em dois experimentos ninfas de M. spectabilis e M. fimbriolata foram expostos aos patógenos, em condições de laboratório e casa-de-vegetação e a partir daí foram selecionados os isolados mais patogênicos para cada espécie de praga. Em seguida, avaliou-se a eficiência de quatro métodos de aplicação de NEPs (pipetador, pulverização sobre ninfas com e sem espuma e inseto-cadáver) sobre a cigarrinha-das-pastagens, em casa-de-vegetação. Por último, avaliou-se a eficiência de uma espécie de NEP sobre ovos e adultos da cigarrinha-das-pastagens. Todos os isolados testados são patogênicos às ninfas das cigarrinhas causando mortalidade de 40 a 92% e 38 a 90% em condições de laboratório e 14 a 71% e 48 a 72% em casa-de-vegetação, para M. spectabilis e M. fimbriolata, respectivamente. Os métodos de aplicação mais eficientes foram o de pulverização sobre ninfas com espuma e inseto-cadáver, não havendo diferença na eficiência provocada pelas concentrações e isolados utilizados. Observou-se que não ocorre infecção de NEPs sobre ovos de cigarrinha-das-pastagens. Os adultos da cigarrinha não foram infectados pelos NEPs, e não houve redução no número de ovos em função da presença do patógeno. Dos isolados testados, os mais eficientes foram Steinernema riobravis, S.feltiae e Heterorhabditis amazonensis RSC1 para M. spectabilis e S. feltiae, S. riobravis, H. baujardi LPP7 e S. carpocapsae para M. fimbriolata. Conclui-se portanto que nematóides entomopatogênicos podem ser utilizados no controle de cigarrinhas do gênero Mahanarva, sendo incluídos em programas de manejo integrado, devendo ser empregados contra as ninfas, pulverizados sobre a espuma ou através de inseto-cadáver.
The spittlebugs belonging to the genus Mahanarva cause damage to the Poaceae family cultures, like signal grass, elephant grass and sugar cane, by the sap feeding on roots (immature phase) and leaves (adult phase). With the increase demand to reduce use of chemical insecticides for the insect pests’ control, comes the need to develop new control methods. In this scenario, the biological control gains highlight and in the spittlebugs case, the entomopathogenic nematodes (EPNs) are potential control agents, exploring the soil surface, the same pest environment while it feeds on roots. Thus, with the aim to know the EPNs’ action and to screening strains of these pathogens against the leaf spittlebug, Mahanarva spectabilis, and the root spittlebug, Mahanarva fimbriolata, experiments were conducted with various EPNs strains over different insect development phases. In two experiments M. spectabilis and M. fimbriolata nymphs were exposed to the pathogens, in laboratory and greenhouse conditions, and then were screened the more pathogenic strains to each pest species. Following, were evaluated the efficiency of four application methods of EPNs (pippeting, spray over nymphs with and without froth and infected host cadaver) over the leaf spittlebug, at greenhouse. At last, were evaluated the efficiency of an EPN species over eggs and adults of the leaf spittlebug. All tested strains are pathogenic to the spittlebugs nymphs causing 40-92% and 38-90% mortality at laboratory and 14-71% and 48-72% at greenhouse, to M. spectabilis and M. fimbriolata, respectively. The more efficient application methods were spray over nymphs with froth and infected host cadaver, with no difference because the concentrations and strains. Observations showed that don’t occurs eggs infection by EPNs in leaf spittlebugs. The leaf spittlebug adults not were infected by the EPNs, and no egg reduction were observed. The most pathogenic EPNs strains were Steinernema riobravis, S.feltiae and Heterorhabditis amazonensis RSC1 to M. spectabilis and S. feltiae, S. riobravis, H. baujardi LPP7 and S. carpocapsae to M. fimbriolata. Thus I conclude that entomopathogenic nematodes can be utilized to control Mahanarva genus spittlebugs, and can be inserted in integrated pest management programs, should to be applied over nymphs exclusively, sprayed over the froth or through infected host cadevers.

Thesis (PhD)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Entomopathogenic nematodes have the potential to be outstanding biocontrol agents against agricultural pest insects. Combined with their bacterial symbionts, these biocontrol agents have proven to be very effective against numerous pests. The nematodes belong to the families Steinernematidae and Heterorhabditidae, and are ideal to be used in, and integrated with, pest management systems. There is a dire need for new and innovative methods to control agricultural pests, as numerous pest insects have developed resistance against broad-spectrum insecticides. Together with the environmental impact of these insecticides and the safety aspect regarding humans and animals, the need to develop new technologies, including entomopathogenic nematodes for pest management, is high. In this study, the associated symbiotic bacteria of three entomopathogenic nematodes species were isolated, and the potential of two nematode species to be successfully mass cultured in liquid medium was evaluated. Regarding the symbiotic bacteria, results from the study showed that bacteria species from all three nematode species, Heterorhabditis noenieputensis, Steinernema khoisanae and Heterorhabditis zealandica, were novel. Heterorhabditis noenieputensis was isolated in the Mpumalanga province during a previous survey conducted in citrus orchards. The bacterium isolated from this nematode belongs to the genus Photorhabdus, and bear closest similarity (98.6%) to the type strain of P. luminescens subsp laumondii (TT01T). Photorhabdus luminescens subsp. noenieputensis subsp. nov., derives its name from the area where the nematode was sourced, namely the farm Springbokvlei, near the settlement Noenieput close to the Namibian border. Thus far, 85 Steinernema spp. have been described worldwide, including S. khoisanae which was isolated in the Western Cape province of South Africa. Four S. khoisanae strains, namely SF87, SF80, SF362 and 106-C, were used for characterisating the new bacteria from different localities in South Africa. Using the neighbor-joining method, all the strains were aligned with 97% homology to the 16S rRNA sequences of several Xenorhabdus- type strains, indicating that they belonged to the same genus. The multigene approach was used to distinguish between the Xenorhabdus spp. and partial recA, dnaN, gltX, gyrB and infB gene sequences of the various strains were analysed. The bacterium species was named Xenorhabdus khoisanae sp. nov. after the nematode from which it was isolated. The results showed that the third bacterium species, which was isolated from H. zealandica, was new. The sequence of the bacteria strain clustered with the type strains of P. temperata and P. asymbiotica, indicate that it belonged to the genus Photorhabdus. This is the first study to show that H. zealandica associates with a luminescent Photorhabdus species, rather than with the known non-luminescent P. temperata. The potential of H. zealandica and Steinernema yirgalemense mass culture in liquid was investigated. Results illustrated that H. zealandica and its P. luminescens symbiont can be successfully cultured in liquid. However, two generations occurred during the process time, instead of the desirable one-generation. The growth curve of the symbiotic bacteria during the process time was measured, in order to determine when the stationary phase was reached, with the results showing this to occur after 36 h. Therefore, the optimum amount of time required for inoculating the IJs and for aiding in maximum infective juvenile (IJ) recovery is 36 h for adding the nematodes post pre-culturing of the bacteria. Future research goals should be to increase the percentage recovery in liquid culture, which would increase the number of nematodes produced per ml, which would, therefore, reduce the processing time significantly. The results from mass culturing the second nematode species, S. yirgalemense, indicated an asynchronous nematode development in the first generation. Growth curves were performed with the symbiotic bacteria that showed the exponential phase of Xenorhabdus started after 15 h, and that, after 42 h, the stationary phase was reached, with an average of 51 × 107 cfu·ml-1. Bioassays were performed to compare the virulence between in vitro- and in vivo-produced nematodes, with the results showing that the in vitro-produced nematodes were significantly less virulent than were the nematodes produced in vivo. The success obtained with the production of S. yirgalemense in liquid culture can serve as the first step in the optimising and upscaling of the commercial production of nematodes in industrial fermenters. The last aim of the current study was to determine when Xenorhabdus reached the stationary phase, when it is grown in a 20-L fermenter, as this would be the optimum time at which to add the IJs of S. yirgalemense. Such characteristics as the effect of stationary phase conditions on the bacterial cell density and on the DO2 rate in the fermenter were investigated. The results showed that the stationary phase of Xenorhabdus was reached after 36 h at 30˚C, which took 6 h less than did the same procedures followed with the Xenorhabdus sp. cultured in Erlenmeyer flasks on orbital shakers. This is the first step toward the liquid mass culturing of S. yirgalemense in industrial-size fermenters. Data from this study indicated the optimum amount of time that is required for adding nematodes to the bacterial culture in the fermenter, and for ensuring the optimum recovery of IJs, as well as a subsequent high yield of nematodes within a minimum processing time. This is the first report of its kind to investigate comprehensively the successful liquid culture of two South African entomopathogenic nematode species for the sole purpose of evaluating potential commercialisation. Results emanating from this study could be used as groundwork in future, in combination with similar research such as culturing nematodes intensively in large fermenters.
AFRIKAANSE OPSOMMING: Entomopatogeniese nematodes het die potensiaal om as doeltreffende biologiese beheeragente teen sleutelplaaginsekte gebruik te word. Elke nematood werk interaktief met ‘n spesifieke bakterium. Entomopatogeniese nematodes, behorende tot die families Steinernematidae en Heterorhabditidae, is ideale kandidate vir gebruik in ‘n geïntegreerde plaagbestuurprogram. Tans is daar ʼn behoefte vir nuwe metodes vir die beheer van plaaginsekte, omdat meeste insekte reeds weerstand opgebou het teen bestaande plaagdoders. As gevolg van die negatiewe impak van plaagdoders op die omgewing, asook kommer oor veiligheid vir die mens en diere, is die ontwikkeling en gebruik van alternatiewe plaagbeheermiddels noodsaaklik. In die eerste deel van die studie word drie nuwe bakterie spesies geïsoleer en beskryf. Resultate van hierdie studie het aangetoon dat die bakterië spesies vanuit die nematode spesies, Heterorhabditis noenieputensis, Steinernema khoisanae, en Heterorhabditis zealandica, tot dusver onbeskryf was. Eersgenoemde, H. noenieputensis, is afkomstig van ʼn sitrusboord in die Mpumalanga Provinsie. Die bakterie hieruit geïsoleer behoort tot die genus Photorhabdus en is biologies verwant (98.6%) aan P. luminescens subsp laumondii (TT01T). Die bakterie is benaam as Photorhabdus luminescens subsp. noenieputensis nov. en is na die nematood waaruit dit geïsoleer is vernoem. Tot dusver is wêreldwyd 82 spesies van Steinernema spp. beskryf, insluitende S. khoisanae van die Weskaap provinsie. Vier bakterie isolate is van S. khoisanae, SF87, SF80, SF362 en 106-C geïsoleer. Die buur-koppeling metode was gebruik om te bepaal dat hierdie bakterie isolate tot 97% ooreenstem met verskeie isolate van Xenorhabdus se 16S rRNA DNS volgordebepalings. Om tussen Xenorhabdus spp. te onderskei is ʼn multi-geen benadering gebruik deur gedeeltelike recA, dnaN, gltX, gyrB en infB DNS basispaar volgordebepalings van die verskeie isolate te bepaal. Hierdie bakterie isolaat is soortgelyk ook vernoem as, Xenorhabdus khoisanae sp. nov., na die nematood waaruit dit geïsoleer is. Die derde onbekende bakteriële spesie is uit H. zealandica geïsoleer. Die DNS basispaar volgordebepaling van die 16S geen van SF41 toon aan dat dit in dieselfde groep as P. temperata en P. asymbiotica val en sodoende aan die genus Photorhabdus behoort. Hierdie is die eerste studie met die bevinding dat H. zealandica ook met ʼn ander bakterie spesie geassosieer kan word buiten die normale P. temperata spesie. Die tweede deel van die studie gaan oor die teling van twee nematood spesies, H. zealandica en Steinernema yirgalemense, en hulle is geëvalueer vir hulle potensiaal om geteel te word in ʼn vloeibare medium. Die resultate het gewys dat H. zealandica met sy P. luminescens simbiont suksesvol in vloeistof aangeteel kan word, ten spyte van die feit dat daar twee generasies ontwikkel het, in plaas van die meer ideale enkel generasie. Die groeikurwe van die simbiotiese bakterie was gemonitor om te bepaal wanneer die stasionêre fase bereik word. Die resultate toon dat hierdie fase na 36 uur bereik was. Dus was die infektiewe nematode larwes eers na 36 uur tot die vloeibare medium waarin die bakterie geteel was bygevoeg. Navorsing in die toekoms moet dus gefokus wees om die persentasie herwinning van die infektiewe larwes te verhoog. Dit sal daartoe lei dat meer nematodes per ml geproduseer kan word en ook die prosesseringstyd van die nematodes verminder. ʼn Tweede nematode spesie, S. yirgalemense, was ook in vloeistof geteel. Hier het ʼn asinkroniese ontwikkeling in die eerste generasie plaasgevind wat problematies is. Groeikurwes is bepaal van die bakteriële simbiont en die resultate het gewys dat die groeifase van Xenorhabdus na 15 uur in aanvang geneem het en dat die stasionêre fase bereik was na 42 uur met ʼn gemiddelde van 51 × 107 selle·ml-1. Die virulensie van nematodes wat in vitro geteel is, is vergelyk met die virulensie van nematodes wat in vivo geteel is en die resultate het getoon dat die in vitro geteelde nematodes minder virulent was. Die teling van S. yirgalemense in vloeistof was oor die algemeen meer suksesvol as die teling van H. zealandica in dieselfde medium. Die doelwit van die laaste gedeelte van hierdie studie was om te bepaal wanneer Xenorhabdus die stasionêre fase bereik wanneer dit in ʼn 20-L fermenter gekweek word. Dit bepaal sodoende die optimale tyd wanneer die infektiewe larwes van S. yirgalemense bygevoeg behoort te word. Die uitwerking van die stasionêre fase op die bakteriële selle, asook die DO2-konsentrasie in die fermenter, was geëvalueer. Resultate het gewys dat die stasionêre fase van Xenorhabdus na 36 uur bereik was, wat 6 uur korter is as toe dit gekweek is in Erlenmeyer flesse. Hierdie studie is die eerste stap om die massa teling van S. yirgalemense in industriële fermenters suksesvol te bemeester. Die data wat verkry was, het aangedui wat die ideale tydsduur sal wees om die bakteriegetalle te vermeerder voordat die nematode bygevoeg word. Hierdie is die eerste studie wat die teling van twee Suid-Afrikaanse nematode spesies omvattend in vloeistof evalueer het. Die hoof doelwit is om die potensiaal van hierdie nematode spesies, met die oog op kommersiële gebruik, te meet. Die resultate van hierdie studie kan gekombineer word met toekomstige studies in hierdie spesifieke navorsingsveld.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Boophilus microplus (Canestrini,1887) (Acari: Ixodidae) o carrapato dos bovinos é um ectoparasito associados à diversas doenças que podem levar o animal a diminuição de sua produção e até mesmo à morte. O principal meio de controle deste carrapato é realizado por meio de carrapaticidas, os quais, estão possibilitando a disseminação da resistência das populações de carrapatos. Os nematóides entomopatogênicos, têm sido apontados como excelentes candidatos ao controle biológicos de insetos, e trabalhos recentes mostram suas eficácias contra carrapatos.O objetivo deste trabalho foi avaliar os efeitos do isolado LPP1 (proveniente da cidade de Monte Negro, Rondônia, Brasil) da espécie Heterorhabditis indica (Poinar, Karanukar & David, 1992), sobre a biologia reprodutiva de fêmeas ingurgitadas de B. microplus. Foram testadas diferentes concentrações com 75, 150, 300, 600, 1200, 2400 e 4800 juvenis dispersos água destilada, por fêmea. Cada grupo de 30 fêmeas foi separado em seis placas de Petri com areia, cada uma com cinco fêmeas, totalizando 8 grupos. Os tratamentos e o controle foram acondicionados em câmara climatizada a 27 ± 1° C e UR>80%, durante 48 horas. Depois o tempo de exposição, as fêmeas que estavam vivas foram individualmente acondicionadas em potes plásticos, e observadas diariamente até a última morte. Foi observado inicio e final da postura para fêmeas que ovipositaram, data da morte e aspecto pós-morte, para todas as fêmeas. Foram avaliados: peso inicial da fêmea, período de pré-postura, período postura, período de sobrevivência, peso da postura, alteração do peso da fêmea, peso final da fêmea, período de incubação dos ovos (PIO), percentual de eclosão (%EC), índice de produção de ovos (IPO), índice nutricional (IN), percentual de controle (%C). Os pesos iniciais, períodos de pré-postura, do grupo controle em relação a todos os tratamentos não mostraram diferenças. Os pesos finais mostraram diferença entre o grupo controle e os grupos tratados, o que não ocorreu entre os tratamentos. Na alteração do peso da fêmea e índice nutricional houve diferença entre o grupo controle e os grupos tratados, aumentando à medida que a concentração de juvenis crescia. Tanto no período de postura quanto no período de sobrevivência houve evidente redução. A massa de ovos e a porcentagem de eclosão larval foram reduzidas. O índice de produção de ovos do grupo controle mostrouse semelhante a menor concentração e diferente entre os demais tratamentos. Todas as concentrações apresentaram eficácia acima de 95% de controle do carrapato.
The cattle tick Boophilus microplus (Canestrini, 1887) (Acari: Ixodidae) is an ectoparasite associated with various diseases that can reduce animals’ production on even cause their death. The main control method is application of carrapaticides, which can lead to resistant tick populations. Entomopathogenic nematodes have been indicated as excellent candidates for biological control of insect, and recent studies have shown their efficacy against ticks. The objective of this study was to assess the effects of the LPP1 isolate (from Monte Negro, Rondônia, Brazil) of the species Heterorhabditis indica (Poinar, Karanukar & David, 1992) on the reproductive biology of ingurgitated B. microplus females. Different nematode concentrations were tested, with 75, 150, 300, 600, 1200, 2400 and 4800 infective juveniles dispersed in distilled water per female. Each group of 30 females was separated into six Petri dishes containing sand, each with five females, for a total of eight groups including the control. The Petri dishes were then kept in a climate controlled chamber at 27 ± 1° C and UR>80%, for 48 hours. After the exposure time, the females that were still alive were placed individually in plastic cups and observed daily until the last one died. The start and end of laying was observed for females that laid eggs, and the date of death and post mortem aspect were noted for all females. The other parameters recorded were initial weight, pre-laying period, laying period, survival period, egg mass weight, change in weight and final weight of the female ticks, egg incubation period (EPI), larval hatching rate (% HR), egg production index (EIP), nutritional index (NI), and control percentage (%C). There were no differences observed in the initial weight and pre-laying period between the control group and all the treatments. There was a difference in the final weight of the control group and treated groups, but none among the treatments. In relation to female weight and nutritional index, there was a difference between the control group and treated groups, which increased as the concentration of infective juveniles went up. There was an evident reduction in the treated groups both in laying period and survival period. The egg mass and the hatching percentage were smaller in the treated groups. The egg production index was similar in the control group and the treated group with the lowest concentration, and different for the other concentrations. All the treatments with nematodes showed efficacy greater than 95% in controlling the ticks.

The insect parasitoid nematodes are a means boon to agronomy and serve as important bio-pesticides for controlling crop damaging insect pests. These nematodes inhabit moist soils and have been to exist in all the continents excluding Polar Regions. These nematodes have 3rd larval stage infective which is the only free living stage existing outside the host. These infective stages are mutually associated with bacteria which reside in their alimentary canal and duo are responsible for mortality of the insect host. These nematodes are currently given great attention by scientific community because of their insect killing properties and can be used to replace hazardous pesticides. These nematodes include various species belonging to genus Heterorhabditis and Steinernema, and members of insectivorous group of genus Oscheius. Before their use as bio-control agents, these nematodes need to be properly identified. Currently, these nematodes are characterized by using morphological and morphometrical parameters and advanced molecular tools including cross hybridization and scanning electron microscope studies. Their associated bacterial partners are studied through advanced molecular and biochemical techniques. The properly characterized nematodes having more entomopathogenic properties can be easily mass produced through in vitro and in vivo methods. They can be formulated in various carrier materials and supplied to farmers for effective control of damaging insect pests. Several countries have formulated various useful products of entomopathogenic nematodes which are available in markets for use by the farmer community and some have given very effective results. India is still at the early stage in the use of these nematodes for bio-control of insects in agronomy. More research in this field needs to be carried, especially in India to produce effective indigenous nematode products which may prove a boon for agriculture.