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Extensive surveys of entomopathogenic nematodes (EPNs) have been conducted globally to identify native species. In Africa, EPN-related research has gained much attention over the past two decades, with several surveys having been undertaken in different countries, including Benin, Cameroon, Egypt, Ethiopia, Kenya, Morocco, Nigeria, Rwanda, South Africa and Tanzania. Such surveys have led to the description of 37 EPN species and 16 species of symbiotically associated bacteria being documented from Africa. Whereas South Africa and Egypt have made significant progress in the discovery and identification of EPN, in terms of their symbiotic bacteria and pathogenicity testing against pest insects, in many other African countries, the research is still in its early stages, or is else non-existent. Most research conducted so far has focused on laboratory bioassays, while research on the use of nematodes in more natural environments is scant. The present review provides a comprehensive overview of EPNs and their associated symbiotic bacteria from the African continent. The biological control potential of local EPN isolates against various economically important insect pests in Africa is also discussed. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPN) are well-established plant protection tools for the control of insect pests. The release of EPN species is often limited to species that are endemic in the country. Therefore, surveys to check for the presence of EPN species in the country are necessary. Here, a sampling and baiting method based on the in situ attraction of EPN to insects contained in a plastic tube is described. Heterorhabditis downesi was isolated from overgrown dunes at the Baltic coast and Steinernema feltiae from chromic luvisol further inland. This is the first report of the presence of H. downesi in Germany. [ABSTRACT FROM AUTHOR]

Duponchelia fovealis Zeller, is currently considered one of the most important emergent pests of a range of crops. This pest is common in Europe, but its presence in the Americas, particularly Brazil and Mexico, has been only recently reported in strawberry crops. Since its recent arrival in Mexico interest in the potential of different entomopathogens for the control of D. fovealis has increased. Here we evaluated commercial products of the bacterium Bacillus thuringiensis; three different species of entomopathogenic nematodes; and different isolates of four species of entomopathogenic fungi. All pathogens were evaluated against 3rd instar larvae, except nematodes which were evaluated against both larvae and pupae. Analysis revealed significant differences in virulence amongst B. thuringiensis products, where the most virulent was nine times more virulent than the least virulent product. Amongst nematodes, Heterorhabditis bacteriophora was the most virulent and larvae were more susceptible to nematodes than pupae; larval mortalities at the highest dose evaluated (200 infective juveniles [IJs]) were between 80 and 95%, while for pupae they were between 25 and 40%. Mortality of larvae due to entomopathogenic fungi was lower than for the other entomopathogens; the highest mortality observed was 25% caused by an M. anisopliae isolate, although this was not statistically different to other fungal isolates. Overall, our results showed that biological control products based on B. thuringiensis or the nematode H. bacteriophora have the greatest potential; we consider that H. bacteriophora could be more convenient as it infects larvae and pupae. [ABSTRACT FROM AUTHOR]

Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is a major phytosanitary pest of citrus in South Africa. Although several management tools exist, control options registered for use against the soil-dwelling life stages are limited. Both entomopathogenic nematodes (EPNs) and entomopathogenic fungi have been investigated previously, but they have not been studied in combination against T. leucotreta. Thus, this study investigated the interaction of an indigenous entomopathogenic fungus, Metarhizium pinghaense (previously anisopliae) FCM Ar 23 B3 with three indigenous EPNs: Steinernema yirgalemense 157-C, S. jeffreyense J194 and Heterorhabditis noenieputensis 158-C for increased late instar T. leucotreta larval mortality. Before interaction experiments, lethal concentration (LC) values for each of these microbial agents were determined through dose–response bioassays. Heterorhabditis noenieputensis recorded the highest LC50 amongst the nematodes (7.11 IJs/50 µl). Using the pre-determined LC70 value of M. pinghaense and the LC50 values for each of the nematode species, interaction experiments were conducted. Combinations of the nematodes either applied simultaneously with the fungus or at 24, 48, 72 or 96 h post-fungal application showed predominantly additive interactions. Synergy between the simultaneous application of S. yirgalemense and M. pinghaense was found, whilst the interaction between H. noenieputensis and M. pinghaense applied simultaneously and S. jeffreyense applied 24 h post-fungal application, recorded antagonistic interactions. The use of these agents in combination may therefore have the potential to increase control of T. leucotreta soil-dwelling life stages in citrus orchards across South Africa and should be further investigated. [ABSTRACT FROM AUTHOR]

The antagonistic activity of four Philippine EPN isolates of Steinernema abbasi Elawad et al. (SaMBLB) and Heterorhabditis indica Poinar et al., (HiPBCB, HiBSDS, and HiMAP) was investigated against Meloidogyne incognita (Kofoid & White) Chitwood. Fourteen days after inoculation, it was demonstrated that concomitant application of 1,000 live infective juveniles (IJ) of each EPN species and 200 M. incognita IJ significantly reduced root penetration consequently affecting juvenile development to the adult stage of M. incognita. The lowest number of M. incognita was found in plants treated with S. abbasi MBLB (1.90 ± 2.20) and H. indica PBCB (2.05 ± 2.61). Externally, formation of well-developed galls was only observed on tomato plants inoculated with RKN alone indicative of the negative effect of EPN to M. incognita root penetration. However, none of the EPN isolates had positive effect on the growth of M. incognita-treated tomato plants measured through plant height. This study provides the first insight on the biological control potential of these local EPN isolates for the management of M. incognita in the Philippines. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPNs) infect insects and reproduce within the host cadaver. The nematodes use chemotaxis to assist in host-finding. However, the chemotaxis of nematode species in response to insects previously infected by con- and hetero-specific EPN in a sand context has rarely been reported. Our aim was to address the response of Steinernema carpocapsae All (Sc) to Galleria mellonella cadavers infected by con- or hetero-specific EPNs (Heterorhabditis bacteriophora HB1, S. feltiae SN, S. rarum 17 C&E) in sand via chemotaxis assays. Additionally, the effect of different time points post-infection was also evaluated. Results indicated that previously infected G. mellonella larvae repelled infective juveniles (IJs) of Sc (p < 0.05) regardless of the time point post-infection and EPN species (con- or hetero-specific) and had a lower chemotaxis index as compared to that of no larvae addition in both sides. Moreover, it was found that for each of four tested EPN species, EPNs infected insect cadavers released dimethyl disulphide, which was identified by solid-phase microextraction (SPME) coupled to gas chromatography–mass spectrometry (GC–MS). We found that dimethyl disulphide acted as a repellent to Sc infective juveniles and reached a significant effect at the level of 0.106 mol/L. Our findings could provide a better understanding of movement behaviour of EPN infective juveniles in response to insect resources in the presence of con- or hetero-specific EPNs. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of alternate insects hosts Mahanarva spectabilis and Galleria mellonella on the efficacy the entomopathogenic nematode, Heterorhabditis baujardi isolate LPP7, for Rhipicephalus microplus control. In the first experiment, engorged R. microplus females were exposed to entomopathogenic nematode H. baujardi LPP7 with or without the presence of M. spectabilis nymphs or G. mellonella larvae. There were also groups containing only M. spectabilis or G. mellonella exposed to H. baujardi and a control group for each arthropod. In the second experiment, engorged females were exposed to different concentrations of H. baujardi which were reared from M. spectabilis and G. mellonella. Mortality rates of engorged R. microplus females, held together with EPN-infected M. spectabilis or G. mellonella inside, was 100% after five days, while the group containing only ticks reached 86%. EPNs caused reduction (p < 0.05) in the amount of eggs produced by engorged females. In the second experiment, the use of nematodes reared in M. spectabilis and G. mellonella also caused a decrease (p < 0.05) in the egg mass weight of R. microplus. The inhibition rate of egg-laying was greater than 80% for all treatments, reaching 92% in the treatment at a concentration of 800 EPNs/female, with nematodes reared in G. mellonella. We can conclude that, under laboratory conditions, the presence of another host did not reduce the activity of H. baujardi on R. microplus. Infective juvenile of entomopathogenic nematodes reared in M. spectabilis or G. mellonella have similar virulence against R. microplus engorged females. [ABSTRACT FROM AUTHOR]

A survey of entomopathogenic nematodes (EPN) was conducted in Morocco during 2015 and 2016 in three regions with varying topography, climate and vegetation (Meknès-El Hajeb, Ifrane and Tafilalet). EPN were isolated from 14 of 169 soil samples (8%). Molecular and morphological techniques were used for species determination. Nine samples contained heterorhabditids and five samples contained steinernematids. Eight heterorhabditids were identified as Heterorhabditis bacteriophora Poinar 1976, two steinernematids as Steinernema feltiae (Filipjev, 1934), three as belonging to the S. feltiae-group, and one as an unidentified isolate (Heterorhabditis sp.) which gives dark burgundy colour for G. mellonella cadavers. These EPNs were collected mainly from agricultural soils rather than natural habitats, with potential adaptation to specific geography, climate and soil conditions (texture, pH and organic matter content), including six EPN isolates from heavy soils. These data demonstrate that EPN are present in Moroccan soils but at relatively low frequency, so opportunity exists to augment these populations to gain biological control benefits. [ABSTRACT FROM AUTHOR]

The potential of native entomopathogenic nematodes for the control of the brown marmorated stink bug Halyomorpha halys was evaluated in experimental trials in Georgia. Two Georgian strains of Heterorhabditis bacteriophora (HRB, GEO) and Steinernema borjomiense and two Italian strains of H. bacteriophora (HRB, IT) and S. apuliae were used in laboratory assays (22°C and 80% RH) at concentrations of 1000, 500 and 200 infective juveniles (IJs) per adult H. halys. The mortality of tested insects was estimated from the third day after treatment. Differences in mortality of the tested insect were observed between Georgian and Italian strains. At the highest concentration (1000 IJs/adult), mortality (%) of H. halys induced by Georgian strains HRB and S. borjomiense was 53.3 and 40, respectively, at 500 IJs/adult 40 and 33.3, and at 200 IJs/adult 33.3 and 13.3, respectively. Italian strains HRB (IT) and S. apuliae proved more suppressive against the tested insects, with mortality rates of 95.5 and 60, 93.3 and 40 and 73.3 and 33.2%, at concentrations of 1000, 500 and 200 IJs/adult of H. halys, respectively. The present study provides further insights in selection of promising EPN strains to be used against this harmful insect pest, although further studies to test their efficacy under field conditions are needed. [ABSTRACT FROM AUTHOR]

Aedes aegypti, is a major vector of several human diseases such as dengue, yellow fever, chikungunya and Zika virus. Multiple strategies are adopted for its control including eradication of mosquito breeding sites by improving water storage and solid waste disposal as well as treating breeding sites with chemical insecticides. However, continuous use of insecticides has resulted in development of insecticide resistance in Ae. aegypti. This study explores the potential biocontrol of Ae. aegypti by the use of commercial entomopathogenic nematodes, namely Heterorhabditis bacteriophora, H. downesi, H. megidis, Steinernema carpocapsae, S. feltiae and S. kraussei. The pathogenic effect of nematodes (concentrations 10, 250, 500 and 1,000 infective juveniles (IJs)) was assessed against third instar Ae. aegypti in multi-well culture plates for 3 days. The evaluated nematode species were pathogenic to Ae. aegypti, however, their virulence varied significantly. Heterorhabditis bacteriophora and S. carpocapsae were most virulent causing 90-100% mortality at 100 IJs per larva, whereas H. megidis and S. kraussei showed least virulence causing 40-60% mortality. Heterorhabditis downesi and S. feltiae had intermediate virulence. Third instar Ae. aegypti indiscriminately overfeed nematodes triggering melanisation but ingested nematodes overcome the defence system resulting in killing the larvae and reproduced within them. Some of the nematodes were melanised, suggesting a strong humoral defence response by Aedes, nevertheless, with variable degree of melanisation. The melanisation did not stop nematode from multiplying and killing Aedes larvae and thus, they have potential to be developed into a novel strategy for Ae. aegypti control. [ABSTRACT FROM AUTHOR]

Heterorhabditis indica SL0708 is an entomopathogenic nematode isolated from Valle del Cauca-Colombia, whose bacterial symbiont, Photorhabdus luminescens subsp. akhurstii SL0708, has potential to control pests of economic importance in Colombia. Since in vivo production does not supply its demand, this investigation evaluated H. indica SL0708 production on different agar media. Five culture media (I, II, III, IV and V) were evaluated for productivity and pathogenicity of infective juveniles (IJs). IJs emerged between 11 and 16 days after inoculation in all media, with a total of 2.7 × 104 and 4.7 × 106 IJs produced during 15 days after IJs emergence, with maximum productivity at day five and high variability. Pathogenicity to Galleria mellonella larvae was not significantly different between in vitro and in vivo produced IJs on all media tested. Media IV and V were selected for their higher productivity. Subsequently, nematode inoculum size was evaluated in selected media at 2000, 4000 and 6000 IJs ml−1, but significant differences were not observed in productivity and pathogenicity. Lastly, lipid source influence was evaluated in medium IV comparing canola, olive and soy oils. None of the plant-based oils had a significant effect on IJs production and pathogenicity. A medium was selected for H. indica SL0708 IJs production which was suitable in terms of productivity, culture time and pathogenicity of IJs produced. The medium and parameters selected in this study could be applied as an alternative for mass production of this entomopathogenic nematodes. [ABSTRACT FROM AUTHOR]

Limited shelf life of entomopathogenic nematodes severely restricts their use in biological control programs. In a series of experiments, the dehydration and rehydration response of Heterorhabditis bacteriophora infective juveniles (IJs) was investigated under a range of glycerol concentrations, temperatures and incubation periods. Based on the outcome of these initial studies, nematodes dehydrated using the optimal process were formulated in alginate granules to understand how these nematodes would undergo survival formulation in a model carrier. The highest rate of osmotically arrested IJs occurred in the 22% glycerol solution (98.06%). IJ recovery was considerably improved when dehydration was processed at 10% glycerol solution and 15°C. By trapping IJs in calcium alginate, depending on the adjuvants, the survival rate of IJs differed significantly. IJ state (dehydrated or non-dehydrated) and the addition of formaldehyde had a profound effect on IJ viability, though the severity of the effect varied was dependent on whether the IJs were alginate formulated. Among different formulations, the highest viability (84.18%) was observed where dehydrated IJs were formulated in alginate granules containing formaldehyde. The results showed that the concentration of osmotic solution not only determines the percentage of dehydrated IJs but also affect their subsequent recovery in an aqueous environment. Overall, the results indicate that the shelf life of formulated IJs is significantly affected by combination effects of a broad range of factors. Then understanding the interactive mode of actions of involved factors in formulation play a critical role in developing and introducing more efficient formulations. [ABSTRACT FROM AUTHOR]

In this study, the utility of inoculative releases of local strains of Heterorhabditis bacteriophora and Steinernema feltiae isolated from northern New York (NY) State for managing soil-dwelling pests in sod (turfgrass production systems) was evaluated. The objectives of the project were to (a) quantify changes in biocontrol potential during the sod production process and (b) evaluate the potential for the nematodes to suppress populations of soil-dwelling turf pests following harvest and installation at a new site. A field study was conducted on four sod fields in central NY State on soils with varying texture and organic matter content, and a post-harvest sod installation study was performed in the greenhouse on a sandy loam soil. Nematode-induced mortality of Galleria mellonella was increased significantly one month following inoculation but differed between fields with different soil types, likely due to variation in soil organic matter content. In the following year, nematode persistence in sod fields was low, likely driven by moderate to severe drought conditions. In contrast, upon harvest and installation, significant nematode-induced mortality was observed in soil receiving an installation of muck-produced sod. Enhanced nematode-induced mortality was detected in both the greater wax moth and third instar Japanese beetle larvae. This study indicates that inoculation of sod with entomopathogenic nematodes can improve biocontrol potential during sod production and after harvest, however, the utility of this practice is sensitive to soil conditions, and likely most efficacious on coarse-textured soils with high organic matter. [ABSTRACT FROM AUTHOR]

A survey was undertaken to determine the diversity and frequency of endemic entomopathogenic nematodes (EPN) in subtropical regions in the Mpumalanga, Limpopo and KwaZulu-Natal provinces of South Africa. A total of 136 soil samples were randomly taken from cultivated and uncultivated habitats, including subtropical fruit tree orchards (avocado, litchi, macadamia, mango and guava) and adjoining natural vegetation. EPNs were isolated from 14 samples (10.3%) by means of baiting withTenebrio molitorlarvae.Heterorhabditiswas the most common genus isolated from 12 samples, whereas only twoSteinernemaspecies were isolated. The most commonHeterorhabditisisolated wereHeterorhabditis noenieputensisandH. zealandica,which were both isolated from four samples each. The present report is the first occurrence ofH. taysearaeandH. baujardiin South Africa. The twoSteinernemaspecies are both unknown species. Laboratory bioassays were conducted to determine the potential of seven native EPN isolates to control the false codling moth (Thaumatotibia leucotreta) (FCM). Last instar FCM larvae were found to be most susceptible toS. yirgalemense(157-C),H. zealandica(WS 23) andSteinernema litchii(WS9), when exposed to 50 IJs/50 µℓ water for 48 h, causing 100%, 94.2% and 93.5% mortality, respectively. [ABSTRACT FROM PUBLISHER]

The scarab beetlePopillia japonica, a pest native to northern Japan, has been recently found in Italy. Entomopathogenic nematodes are useful for biological control of this invasive insect. Previous work showed that 1st and 2nd larval stages are more susceptible to nematodes than 3rd instars. We tested the effectiveness ofHeterorhabditis bacteriophorain the laboratory againstP. japonica3rd instars. Experiments were conducted in Italy with larvae field collected in the fall, winter and spring, showing a significant decrease in effectiveness from the fall to spring. [ABSTRACT FROM PUBLISHER]

Entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are obligate insect pathogens. Their favourable characteristics as biocontrol agents have resulted in some species of EPNs being released globally and widely used for the control of diverse insect pests. In this review, we consider the occurrence of currently described EPN species, including those that have been released globally for commercial purposes. We also discuss the contribution of regulation policies to the global distribution of these species and issues that influence import regulations. Possible non-target effects, the use of commercial versus native EPNs and the possible interaction between these species are considered. Finally, we provide a view as to whether existing policies adequately deal with the risks associated with the global movement of EPNs and we suggest future directions that should be considered for the use of EPNs as biological control agents. [ABSTRACT FROM AUTHOR]

Stacked wooden fruit bins are frequent overwintering sites for overwintering diapausing codling moth larvae. Control strategies against the codling moth (Cydia pomonella) (Lepidoptera: Tortricidae) in South Africa have been hampered by the reinfestation of orchards from nearby stacked infested fruit bins and by the movement of infested bins between orchards. Worldwide, wooden fruit bins are systematically being replaced with plastic bins, however in South Africa this will not be accomplished in the near future. The objective of this study was to evaluate the potential of two recycled commercially available entomopathogenic nematode (EPN) species,Heterorhabditis bacteriophoraandSteinernema feltiae, as well as of a local species,Steinernema yirgalemense, to disinfest miniature wooden fruit bins under controlled conditions in the laboratory. After dipping miniature bins loaded with codling moth larvae in a suspension of 25 IJs/mL of each of the three EPN species, under optimum conditions of temperature and humidity, the highest percentage of control was obtained usingS. feltiae(75%). The addition of adjuvants significantly increasedS. feltiaeinfectivity to >95%, whereas it did not result in a significant increase inH. bacteriophoraorS. yirgalemenseinfectivity. [ABSTRACT FROM AUTHOR]

Five field surveys for indigenous entomopathogenic nematodes (EPNs) were conducted in 22 semi-natural and 17 small-holder farming habitats across 16 districts of different altitudes in the northern, eastern, southern and Kigali city provinces of Rwanda. In 2014, 216 mixed soil samples were collected and subsamples thereof baited withGalleria mellonellaorTenebrio molitorlarvae. Five samples from five locations and habitats were positive for nematodes (2.8%). Nine nematode species/strains were isolated and five successfully maintained. DNA sequence comparisons and morphological examinations revealedSteinernema carpocapsae,Heterorhabditis bacteriophora, as well as two steinernematids and one heterorhabditid with no species designation. The isolates (strains) were namedSteinernemasp. RW14-M-C2a-3,Steinernemasp. RW14-M-C2b-1,Steinernema carpocapsaeRW14-G-R3a-2,H. bacteriophoraRW14-N-C4a andHeterorhabditissp. RW14-K-Ca. These are the first records of naturally occurring EPNs in Rwanda. It is also the first record ofS. carpocapsaefrom Africa. FindingH. bacteriophorafrom tropical rather than temperate Africa was surprising. The found nematodes will serve as the basis for efficacy screening, and for mass production in a biocontrol agent factory at Rubona Research Centre of the Rwanda Agriculture Board with the ultimate aim of delivering effective, safe and environmentally benign pest control for soil-inhabiting pests. [ABSTRACT FROM AUTHOR]

The biological traits of the entomopathogenic nematodes (EPNs), Steinernema carpocapsae and Heterorhabditis bacteriophora, against the larvae of the leopard moth, Zeuzera pyrina were evaluated in the laboratory. The traits included pathogenicity, penetration potential as well as foraging behaviour. Plate assays were performed using a range of EPN concentrations (5, 10, 20, 50 and 100 infective juveniles (IJs) per larva). The LC50 values for S. carpocapsae and H. bacteriophora were 6.4 and 8.4 IJs larva-1 after 72 h. Both EPN species caused high mortality in branch experiments. Significantly higher mortality rates occurred in the larger larvae after exposure to S. carpocapsae. Both EPN species successfully penetrated the Z. pyrina larvae as well as larvae of Galleria mellonella L. (Lepidoptera: Galleridae).The proportional response of H. bacteriophora to host-associated cues was strongly higher than S. carpocapsae in Petri dishes containing agar 1, 12 and 24 h after EPN application. These results highlight the efficiency of EPNs for the control of Z. pyrina larvae. However, due to the cryptic habitat of Z. pyrina larvae in their galleries in the trees, field trails need to be conducted to further evaluate this potential. [ABSTRACT FROM AUTHOR]

Rose sawfly,Arge ochropus(Gmelin), is one of the most important pests of ornamental plants such as roses and wild rose bushes in Northern Iran. We investigated the interactions between the insecticides imidacloprid and the entomopathogenic nematodesHeterorhabditis bacteriophoraandSteinernema carpocapsaeas control agents of fifth-instar larvae in the laboratory. The larvae were very susceptible toS. carpocapsae(LC50: 21 infective juvenile per larva) andH. bacteriophora(LC50: 32). Combinations of two imidacloprid rates (LC30and LC50) and four rates of each nematode species (LC25–LC75) were tested. Combinations with the lower imidacloprid rate except for that with the highestH. bacteriophorarate caused higher mortality than both respective single-agent treatments. In combination with the higher imidacloprid rate, only one combination withH. bacteriophoraand two combinations withS. carpocapsaecaused higher mortality than both respective single-agent treatments. Interactions were generally stronger at the lower imidacloprid rate and were stronger forS. carpocapsae(synergistic in seven combinations, additive in one) than forH. bacteriophora(synergistic in two, additive in six). Synergistic imidacloprid-S. carpocapsaecombinations could be a useful tool for the control ofA. ochropuslarvae that would simultaneously control other common pests susceptible to imidacloprid. [ABSTRACT FROM PUBLISHER]

In laboratory studies, we demonstrated that five native entomopathogenic nematode species/isolates caused 100% mortality ofSpodoptera ciliumlarvae, a soil surface-feeding pest of turfgrass. At 25 infective juveniles/cm2applied to sod, two selected Turkish species,Steinernema carpocapsaeandHeterorhabditis bacteriophora(Sarigerme isolate), averaged 77% and 29% larval mortality, respectively. [ABSTRACT FROM AUTHOR]

We determined the mortality of adult tickDermacentor silvarumOlenev after it was exposed to five entomopathogenic nematode species:Steinernema carpocapsaeBJ (Sc BJ),S. glaseriNC32 (Sg NC32),S. ceratophorumD43 (Sc D43),S. feltiaeOtio (Sf Otio) andHeterorhabditis bacteriophoraE-6-7 (Hb E-6-7). All five species had lethal effects on adult ticks, and caused significant decreases in the amount of eggs laid by engorged female ticks (P< 0.05). Among them, Hb E-6-7 and Sc BJ were the most pathogenic to female adult ticks, with mortalities ranging from 70 to 90% (P< 0.05). Engorged females were more susceptible than unfed and partially fed females. The cumulative mortalities of engorged females exposed to Hb E-6-7 and Sc BJ for 14 days were 90%, with LT50at 6.3 and 7.0 days, respectively. Dose-dependent effect was observed in the oviposition of the ticks after they were exposed to nematodes at concentrations of 1000–5000 IJs/dish. When the concentration was higher than 5000 IJs/dish, dose dependent effects disappeared (P> 0.05). All five nematode species were lethal to unfed male ticks, and there was significant difference in mortality when compared to the control group (P< 0.05); however, the pathogenicity varied among them. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPNs) from the families Steinernematidae and Hererorhabditidae are considered excellent biological control agents against many insects that damage the roots of crops. In a regional survey, native EPNs were isolated, and laboratory and greenhouse experiments were conducted to determine the infectivity of EPNs against the cucurbit fly,Dacus ciliatusLoew (Diptera: Tephritidae). Preliminary experiments showed high virulence by a native strain ofHeterorhabditis bacteriophoraPoinar (Rhabditida: Heterorhabditidae) and a commercial strain ofSteinernema carpocapsaeWeiser (Rhabditida: Steinernematidae). These two strains were employed for further analysis while another native species,Steinernema feltiae, was excluded due to low virulence. In laboratory experiments, larvae and adult flies were susceptible to nematode infection, but both nematode species induced low mortality on pupae.S. carpocapsaehad a significantly lower LC50value against larvae thanH. bacteriophorain filter paper assays. Both species of EPNs were effective against adult flies butS. carpocapsaecaused higher adult mortality. When EPN species were applied to naturally infested fruit (150 and 300 IJs/cm2), the mortality rates ofD. ciliatuslarvae were 28% forS. carpocapsaeand 12% forH. bacteriophora. Both EPN strains successfully reproduced and emerged from larvae ofD. ciliates. In a greenhouse experiment,H. bacteriophoraandS. carpocapsaehad similar effects on fly larvae. Higher rates of larval mortality were observed in sandy loam and sand soils than in clay loam. The efficacy ofS. carpocapsaeandH. bacteriophorawas higher at 25 and 30°C than at 19°C. The results indicated thatS. carpocapsaehad the best potential as a biocontrol agent ofD. ciliatus, based on its higher virulence and better ability to locate the fly larvae within infected fruits. [ABSTRACT FROM AUTHOR]

The susceptibility of potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) to native and commercial strains of entomopatho-genic nematodes (EPNs) was studied under laboratory conditions. Native strains of EPNs were collected from northeastern Iran and characterised as Steinernema feltiae and Heterorhabditis bacteriophora (FUM 7) using classic methods as well as analysis of internal transcribed spacer (ITS) and D2/D3 sequences of 28S genes. Plate assays were performed to evaluate the efficiency of five EPN strains belonging to four species including Steinernema carpocapsae (commercial strain), S. feltiae, Steinernem glaseri and H. bacteriophora (FUM 7 and commercial strains). This initial assessment with 0, 75, 150, 250, 375 and 500 IJs/ml concentrations showed that S. carpocapsae and H. bacteriophora caused the highest mortality in both larval and prepupal stages of P. operculella, PTM. Thereafter, these three strains (i.e. S. carpocapsae, H. bacteriophora FUM 7 and the commercial strains) were selected for complementary assays to determine the effects of soil type (loamy, loamy-sandy and sandy) on the virulence of EPNs against the second (L2) and fourth instar (L4) larvae as well as prepupa. A soil column assay was conducted using 500 and 2000 IJs in 2-ml distilled water. Mortality in the L2 larvae was not affected by the EPN strain or soil type, while there was a significant interactive effect of nematode strains and soil type on larval mortality. The results also showed that EPN strains have higher efficiency in lighter soils and caused higher mortality on early larvae than that in loamy soil. In L4 larvae, mortality of PTM was significantly influenced by nematode strain and applied concentrations of infective juveniles. The larval mortality induced by S. carpocapsae was higher than those caused either by a commercial or the FUM 7 strain of H. bacteriophora. Prepupa were the most susceptible stage. [ABSTRACT FROM AUTHOR]

An approach to ensure effective pest biocontrol would be to select native isolates of biological control agents (BCAs). A survey to isolate entomopathogenic fungi (EPF) from a hazelnut growing area has been carried out. EPF were recovered from 133 of the 295 soil samples. The main species isolated wereMetarhizium anisopliae sensu lato(36%) andBeauveria bassiana sensu lato(42.8%). With regard to controlling abiotic factors, altitude had an effect on the distribution ofB. bassiana, but not onM. anisopliae. Cropping system did not have an effect on the occurrence of these EPF, while pH appeared as a predictive variable for both. In addition, we tested the virulence of six of these isolates: threeM. anisopliaeand three ofB. bassianaagainst larvae ofCurculio nucumL. The highest larval mortality (reaching 80%) was due toM. anisopliae(strain 34) when applied in simultaneous combination with four entomopathogenic nematode species:Steinernema carpocapsae(strain B14),Steinernema feltiae(strain D114),Steinernema.sp. (strain D122) andHeterorhabditis bacteriophora(strain DG46). The effect of nematodes was greater and no antagonistic or synergistic effects were observed. [ABSTRACT FROM AUTHOR]

The entomopathogenic nematode Heterorhabditis bacteriophora is commercially used in biological control of soil dwelling insect pests. It reproduces by autogamy (hermaphrodites) enabling the production of inbred lines, but also by amphimixis (through mating of male and female) which allows cross-breeding. When H. bacteriophora is produced in liquid culture, copulation of male and female is prevented and reproduction is solely by self-fertilisation of hermaphrodites. When reared in insects, crosses are possible resulting in heterozygous offspring. Heat and desiccation tolerance of these nematodes have been successfully improved by selective breeding. Trait deterioration was prevented by producing homozygous inbreds through consecutive reproduction in liquid culture, the method also used for commercial mass production. In this study, we investigated possible heterosis effects in desiccation and heat tolerance after cross-breeding of homozygous inbred lines of H. bacteriophora. Increased desiccation tolerance of the heterozygous progeny in comparison to homozygous inbred lines was recorded indicating that heterosis is a possible means for further improvement of this trait. In contrast, the heat tolerance of the heterozygous offspring was lower than that of the homozygous population. The results provide evidence for the tremendous potential of classical genetics to improve beneficial traits of a biological control agent and carry domestication of H. bacteriophora a significant step forward. [ABSTRACT FROM AUTHOR]

The effects of a new species Heterorhabditis sp. beicherriana on the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and malondialdehyde (MDA) content of the host were studied. Last-instar larvae of Galleria mellonella were used as host insects and were experimentally infected with H. beicherriana at 0, 20, 40, 80 infective juveniles (IJs) per insect. At 0, 8, 16, 24, 32 and 40 h after infection, activities of SOD, POD, CAT and MDA content were determined in extracts from infected and control insects. We found that H. beicherriana infection resulted in gradually increased activities of SOD, POD and CAT the first day and decreased activities of these enzymes thereafter. However, MDA content in the insects of both control and IJ-inoculated groups stayed at a similar level at 24 h post-infection, but a significant decrease of MDA content in inoculated groups was recorded after 32 h of the infection, which is 8 hours later than the activities of SOD, POD and CAT were significantly increased. Our results suggest that H. beicherriana infection increases the level of oxidative stress and antioxidative responses in the larval G. mellonella, and it seems that oxidative damage contributes to cell death in this host. [ABSTRACT FROM PUBLISHER]

We tested the effect of host density on entomopathogenic nematode efficacy in 1-L pots with grass and soil. In four experiments, combinations ranged from somewhat resistant hosts (oriental beetle, Anomala orientalis, or northern masked chafer, Cyclocephala borealis, with Heterorhabditis bacteriophora) over more susceptible hosts (Japanese beetle, Popillia japonica, with Steinernema glaseri) to a highly susceptible host (P. japonica and S. scarabaei). In each experiment, four larval densities were exposed to two nematode rates over a 14-day period. A significant effect of host density on nematode efficacy occurred only in the A. orientalis–H. bacteriophora combination, but there was no clear trend in the data. This suggests that an exhaustion of available nematode populations to less lethal levels by high host numbers was counteracted by other factors such as increased chances for nematode-host contact and increased host susceptibility due to stress via reduced food resources and increased aggression between larvae. [ABSTRACT FROM PUBLISHER]

Field experiments were conducted in turf maintained under golf course fairway conditions in May, June, and August 2009 and in August and September 2010 to evaluate the ability of entomopathogenic nematodes to control larval populations of the black cutworm, Agrotis ipsilon, on golf courses. Commercial products containing the entomopathogenic nematodes Heterorhabditis bacteriophora, Steinernema carpocapsae, S. feltiae, and S. riobrave were applied at 1.0 or 2.5×109 infective juveniles per ha against fourth-instar black cutworms. Larval mortality and turf damage were evaluated at 4 and/or 7 days after treatment (DAT). Steinernema carpocapsae was the best performing species due to a combination of high control rates (average 83%), most consistent results (70-90% range), high speed of kill (average 68% at 4 DAT), and prevention of significant turf damage despite very high larval densities at 0 DAT. Efficacy of S. feltiae and H. bacteriophora was often similar to that of S. carpocapsae but overall less consistent. Short-term persistence of the nematodes was evaluated in four turfgrass sites maintained under golf course putting green, fairway, or rough conditions in June and August 2009 by baiting soil samples at 0, 4, 7, and 14 DAT. Relative to recovery immediately after application, at least 50% of S. feltiae and 25% of S. carpocapsae consistently persisted up to 4 days in one of the greens and up to 7 days in some trials. Our finding suggests that S. carpocapsae and S. feltiae may provide adequate black cutworm control in golf course turf under moderate summer temperatures. [ABSTRACT FROM AUTHOR]

The potential of using an entomopathogenic nematode, Heterorhabditis zealandica Poinar, together with different test mulches (pine chips, wheat straw, pine wood shavings, blackwood and apple wood chips) to control diapausing codling moth, Cydia pomonella (L.) larvae was evaluated. Mesh cages were identified as a suitable larval-containment method. High levels of codling moth mortality were obtained when using pine wood shavings as mulch (88%) compared to pine chips, wheat straw, blackwood and apple wood chips (41-88%). Humidity (>95% RH) has to be maintained for at least 3 days to ensure nematode survival. It was also proven that nematodes had the ability to move out of infected soil into moist mulch, to infect the codling moth larvae residing at heights of up to 10 cm. Field experiments showed the importance of climatic conditions on nematode performance. Low temperatures (<15°C) recorded during the first trial resulted in low levels of control (48%), as opposed to the 67% mortality recorded during the second trial (temperatures ranged between 20 and 25°C). Low levels of persistence (<10%) were recorded in the mulches post-application. The study conclusively illustrated some of the baseline requirements fundamental to the success of entomopathogenic nematodes together with mulches for the control of codling moth. [ABSTRACT FROM AUTHOR]

The survival and infectivity of the infective juveniles of two species of entomopathogenic nematodes, Steinernema feltiae (Rhabditida: Steinernematidae) Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae), were determined after exposure for 72 h to two concentrations of the herbicides glyphosate and MCPA, as well as to the combination of the two herbicides (glyphosate + MCPA). For all herbicide treatments, concentrations and exposure times, S. feltiae was more tolerant to the herbicides than H. bacteriophora. The exposure of entomopathogenic nematodes to glyphosate + MCPA caused significantly higher mortality (26.33-57.33%) than glyphosate (0.67-15%) or MCPA (2.33-19%) alone. These results confirm the synergistic effect of the glyphosate + MCPA combination on the mortality in these nematodes. Nematode infectivity of Galleria mellonella larvae in response to the herbicides presence was evaluated in Petri dish assays containing sterile sand. Nematode infectivity was not significantly reduced by exposure to herbicides in S. feltiae but H. bacteriophora was less tolerant. Synergistic effect was obtained in the nematode mortality test but no synergistic effect was observed in the nematode infectivity assay. Our results suggest that possible synergistic effects of agrochemicals on survival of nematodes should be tested before mixing with entomopathogenic nematodes. [ABSTRACT FROM AUTHOR]

The ability of entomopathogenic nematodes to suppress larval populations of the annual bluegrass weevil, Listronotus maculicollis, was investigated under field conditions over a 3-year period (2006-2008). Combination of nematode species, application rate and timing produced strong numerical yet few statistically significant reductions. Steinernema carpocapsae Weiser, S. feltiae Filipjev, and Heterorhabditis bacteriophora Poinar applied at 2.5×109 IJs/ha reduced first generation late instars between 69 and 94% in at least one field trial. Steinernema feltiae provided a high level of control (94%) to low densities (~20 larvae per 0.09 m2), but gave inadequate control for higher densities (24 and 50% suppression). No significant differences were found among treatment timings. However, applications timed to coincide with the peak of larvae entering the soil (fourth instars) generally performed better than applications made prior to (preemptive) or after the majority of the population advanced from the fourth instar. Nematode populations declined sharply between 0 and 14 days after treatment (DAT). Although nematode populations later increased (at 28 DAT), indicating an ability to recycle within hosts in the environment, they were nearly undetectable 56 DAT when the second generation host larvae were present in the soil. Applying commercially available nematode species at standard field rates cannot reliably reduce L. maculicollis immature densities on golf courses, nor will single applications suppress multiple generations. Future research will need to identify application strategies to improve biocontrol consistency. [ABSTRACT FROM AUTHOR]

The lepidopteran, Cydia splendana, and the coleopteran, Curculio elephas, are the most serious pests of chestnut fruit in Turkey. We evaluated the biological control potential of three Turkish entomopathogenic nematode species, Steinernema feltiae, S. weiseri and Heterorhabditis bacteriophora, against the last instar larvae of C. splendana and C. elephas, both of which occur in the soil from fall (October-November) until mid-summer (August). The optimal temperature for infection, time to death of the hosts, and reproductive potential of the nematodes were determined at 10, 15, 20 and 25°C for both pest species. Cydia splendana was more susceptible to nematode infection than C. elephas. Temperature had a significant effect on the infectivity and development of entomopathogenic nematodes. The cold-adapted S. weiseri and S. feltiae were the most virulent species at 10 and 15°C, whereas the warm-adapted H. bacteriophora was the most effective at 20 and 25°C. In soil pot experiments conducted at 15°C, S. weiseri was the most virulent species against C. elephas and C. splendana. However, our data show that C. elephas larvae had a lower and C. splendana larvae had a higher susceptibility to the nematode species tested. Accordingly, we recommend that future efforts of using entomopathogenic nematodes, especially S. weiseri, be directed against C. splendana and that there be a continued effort to find more virulent nematode isolates against larvae of C. elephas. [ABSTRACT FROM AUTHOR]

Efficacy, persistence and recovery of the nematode Heterorhabditis bacteriophora was tested in the laboratory after application of the nematode to strawberry roots by dipping. To mitigate nematode sedimentation and improve attachment to strawberry roots, carboxy-methyl-cellulose was added to the nematode solution. Mortality of black vine weevil Otiorhynchus sulcatus varied between 90 and 96% in the pot trials. [ABSTRACT FROM AUTHOR]

A series of laboratory and greenhouse experiments evaluated the entomopathogenic nematodes Steinernema scarabaei Stock & Koppenhöfer, Heterorhabditis bacteriophora Poinar, and H. zealandica Poinar for control of second- and third-instar cranberry white grub, Phyllophaga georgiana Horn (Coleoptera: Scarabaeidae), in cranberries. Steinernema scarabaei was the most effective species with 76-100% control at a rate of 2.5×109 IJ/ha in the greenhouse experiments. H. zealandica and especially H. bacteriophora were generally less effective and required rates of 5×109 IJ/ha for acceptable control. Larval stage had no effect on H. zealandica and H. bacteriophora performance, whereas S. scarabaei was more effective against third instars than second instars in the laboratory but not in the greenhouse experiments. Steinernema scarabaei, should it become commercially available, could be an effective alternative to chemical insecticides for P. georgiana management. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPNs) are a group of potentially effective bio-insecticides to which Heterorhabditis bacteriophora, an active ingredient of several commercialised products, belongs. The application of the spray liquid with a motorised hydraulic sprayer introduces several stress factors to EPNs that may reduce their viability. Therefore, the effects of the agitation system, initial temperature of the spray liquid, EPN concentration, and additional air injection on the viability of EPNs were studied. The results clearly illustrate that the hydraulic agitation caused significantly more reduction in viability than the mechanical agitation. A lower temperature of the initial spray liquid, however, yielded a significantly higher EPN viability compared to a higher temperature after hydraulic mixing and so did air injection while EPN concentration did not significantly influence viability. Thus, the results clearly suggest that, with hydraulic agitation, both the re-circulation stress and the temperature increase significantly decreased the EPN viability, while air injection significantly improved it. Therefore, specific application conditions of living organisms in sprayer design and during application should be considered. Furthermore, spray water of less than 20°C should be used to keep temperature under control. [ABSTRACT FROM AUTHOR]

Laboratory and field experiments were performed to determine the efficiency of the entomopathogenic nematode Heterorhabditis bacteriophora against third instar larvae of the tephritid fruit fly Anastrepha ludens . Infection was affected by low (6%) and high (12–24%) soil moisture; the highest prevalence of infection was observed at 9% moisture. LC 50 values were estimated under laboratory conditions at densities of 0.16, 0.26 and 0.64 larvae/cm 3 of sand in containers of different depths (2, 5 and 8 cm) at 10% moisture, and larval ages (third instar, early versus late stadium). Third instar A. ludens were significantly more susceptible to infection early in the stadium than late in the stadium, irrespective of host density (LC 50 ~15 infective juvenile nematodes/cm 2 soil surface). Infection of late stadium third instars was significantly reduced at low density. Application of 115 and 345 infective juvenile nematodes/cm 2 (representing one and three times the laboratory LC 50 at the lowest host density, respectively), in experimental plots in a commercial mango orchard, resulted in 46.7% (range of SE: 45.2–48.1) and 76.1% (SE: 74.8–77.3) infection, respectively. We conclude that H. bacteriophora merits further study as a natural enemy of Anastrepha spp. in tropical regions of the Americas. [ABSTRACT FROM AUTHOR]

We examined the attachment and infectivity of two entomopathogenic nematode species, Steinernema carpocapsae and Heterorhabditis indica, on soldiers and workers in two subterranean termite species, Coptotermes formosanus and C. vastator . In attachment tests with S. carpocapsae, more nematodes attached to soldiers of C. formosanus and C. vastator in the absence of workers compared to soldiers that were in the presence of workers. In tests with soldiers alone, workers alone, and mixture of equal numbers of workers and soldiers, soldiers in the mixed groups had lower mortality than soldiers alone after 1 and 4 days for both termite species. Exposure of small groups of either termite species to S. carpocapsae resulted in higher mortality of soldiers after 1 and 4 days post exposure. Mortality in soldiers alone exposed to H. indica was not significant compared to mortality in mixed groups at 1 day exposure, but was significant after 4 days. In concentration–mortality tests, a significant two-way interaction existed between nematode concentration and termite caste for C. formosanus exposed to S. carpocapsae for 1 and 4 days. A significant effect of nematode concentration was found for C. vastator exposed to H. indica for 1 day. This termite species had lower mortality when exposed to H. indica after 1 and 4 days compared to C. formosanus . At 4 days post exposure to H. indica, the effects of nematode concentration and termite caste were significant. Steinernema carpocapsae caused higher mortality than H. indica , but mortality of workers was higher when exposed to H. indica . Soldiers of both species experienced rapid mortality when exposed to S. carpocapsae , whereas soldiers of C. vastator experienced lower mortality when exposed to H. indica . Thus, our results show that when soldiers alone or workers alone are exposed to the nematodes, there is a differential susceptibility of soldiers and workers to nematode infection with soldiers being more susceptible than workers. In a mixed group of soldiers and workers or workers alone, it appears that grooming behavior of the workers serves as a mechanism to reduce nematode infection of soldiers and workers. The reason for this differential response to nematode infection is that soldiers do not exhibit grooming behavior. [ABSTRACT FROM AUTHOR]

We evaluated the compatibility of two entomopathogenic nematodes, Heterorhabditis bacteriophora HP88 and Steinernema carpocapsae All strain with selected pesticide formulations used in turfgrass in tank-mixes under laboratory conditions. The nematodes were exposed to the recommended rates of pesticides applied in either 100, 300, or 500 L/ha tank-mix volumes in 24-well plates at room temperature for 3 h and infective juveniles (IJ) viability determined, and then tested against Galleria mellonella larvae at 22-26°C for 96 h to assess IJ pathogenicity. We found that S. carpocapsae viability was not affected by any of the pesticides, while aluminum tris and trichlorfon significantly reduced S. carpocapsae pathogenicity at all concentrations. Thiamethoxam and trichlorfon significantly reduced H. bacteriophora viability, while halofenozide, aluminum tris, trichlorfon, and carbaryl significantly reduced H. bacteriophora pathogenicity. Imidacloprid, at the recommended rate 330-440 g AI/ha, significantly increased H. bacteriophora pathogenicity at 500 and 300 L/ha application volume. The integration of these nematode pesticide combinations in turf pest management programs is discussed. [ABSTRACT FROM AUTHOR]

We compared the pathogenicity of the entomopathogenic nematodes Heterorhabditis bacteriophora , Steinernema glaseri , and S. scarabaei against third instars of 12 white grub species . The Japanese beetle ( Popillia japonica ) was highly susceptible to all nematode species . Oriental beetle [Exomala ( =Anomala ) orientalis] , European chafer ( Rhizotrogus majalis ), Asiatic garden beetle ( Maladera castanea ), and the May/June beetles Phyllophaga crinita , Ph. congrua , and Ph . ( Subgenus Phytalus ) georgiana were highly susceptible to S. scarabaei but had mediocre to low susceptibility to H. bacteriophora and S. glaseri. The black turfgrass ataenius ( Ataenius spretulus ) was very susceptible to H. bacteriophora but had mediocre susceptibility to S. glaseri and S. scarabaei. Northern ( Cyclocephala borealis ) and southern masked chafer ( C. lurida ) had mediocre and southwestern masked chafer ( C. pasadenae ) and green June beetle ( Cotinis nitida ) had low susceptibility to all nematode species . [ABSTRACT FROM AUTHOR]

Examines the heritability of the liquid culture mass production potential of the entomopathogenic nematode Heterorhabditis bacteriophora. Production of nematodes in commercial applications; Recovery of dauer juvenile (DJ); Total number of DJs produced in the liquid medium.

Seventeen entomopathogenic nematode species and strains were evaluated for virulence to the grape root borer, Vitacea polistiformis (Harris) in laboratory and greenhouse bioassays. Heterohabditis bacteriophora strain GPS11 and H. zealandica strain X1 produced a larval mortality rate of over 85% of larvae embedded in the root cambium in laboratory bioassays. The nematode species H. marelata and H. bacteriophora strain Oswego produced mortality rates of over 75%. Of the Steinernema species tested, S. carpocapsae strain 'All' performed the best with a mortality rate of 69%. All other nematode species and strains tested, with the exception of S. bicornutum, produced some degree of larval mortality. In the greenhouse bioassays, 93% control was achieved with H. zealandica strain X1 applied at 4 × 109 infective juveniles (IJs) acre1[sup -1] (9.88 × 10[sup 9] IJs ha [sup -1]). H. bacteriophora strain GPS11 successfully reproduced in grape root borer larvae. The numbers of IJs produced within infected larvae were related to larval size. The survival rate of neonate larvae on grape root sections was 61%, which thus provides a means to rear the neonate larvae for bioassays. [ABSTRACT FROM AUTHOR]

We studied the host-finding and dispersion behaviour of Heterorhabditis megidis (strain NLHE 87.3) in the presence of Galleria mellonella or Otiorhynchus sulcatus larvae and strawberry roots. In large Petri dishes (19 cm diameter) filled with moist sand (8% w/w), and incubated at 15°C over 24 h, infective juveniles (IJs) responded positively to the presence of G. mellonella, to roots of a single strawberry plant and to O. sulcatus larvae in direct contact with roots of a single strawberry plant. A neutral or negative response was observed when IJs were presented with only O. sulcatus larvae or a combination of several strawberry plants with O. sulcatus larvae, either in contact or not in contact with the roots. IJs responded strongly to the combination of plant roots and feeding larvae indicating that the tritrophic interaction formed by IJs - O. sulcatus larvae - strawberry plants may be an infochemical-mediated interaction. [ABSTRACT FROM AUTHOR]

The effect of storage temperature (9 and 20°C) on North West European Heterorhabditis megidis isolate UK211 for control of Otiorhynchus sulcatus larvae at 9°C is assessed. O. sulcatus mortality increased from -5.3% (corrected mortality) using freshly produced nematodes, to 27.1% using nematodes that had been cold-stored for 12 weeks. The number of nematodes invading the insect larvae increased almost 27-fold. Nematode storage at 9°C for 11 to 12 weeks weeks resulted in significantly higher O. sulcatus mortality (41%) than storage at 20°C for 2 to 3 weeks (12%). Thus, cold storage does enhance nematode infectivity for O. sulcatus larvae. [ABSTRACT FROM AUTHOR]

Agar plate assays were used to assess the effect of density, incubation time and age of nematodes and the presence of insect hosts on the dispersal of infective juveniles (IJs) of Heterorhabditis megidis (strain NLH-E87.3). IJs dispersed faster and further at high densities than at low densities. Dispersal was also influenced by the age of the IJs. Individuals stored for a period of 1.5 and 4.5 weeks showed to be more active than those stored for 2.5 and 3.5 weeks. The presence of a host insect enhanced the dispersion of nematodes. The increasing in the incubation period showed that IJs responded positively to host cues from Galleria mellonella but poorly to cues from Otiorhynchus sulcatus larvae. [ABSTRACT FROM AUTHOR]

Heterorhabditis indica is a potential agent for the biological control of grubs in sugarcane fields in India. The type strain LN[sub 2] was transferred to monoxenic cultures on its symbiont Photorhabdus luminescens and successfully produced on solid media. In liquid cultures, a mean dauer juvenile yield of 457 000 was obtained with a maximum of 648 000 per ml. Comparatively high yields have not been reported before. Therefore, costs related to the liquid culture production of H. indica will be lower than for other entomopathogenic nematodes currently used in biocontrol. Different bacterial clones had no significant influence on the dauer juvenile yields in liquid media. The exit from the dauer juvenile stage (recovery) after inoculation and the number of hermaphrodites significantly decreased when culture temperature was increased from 25-30[sup °]C; the dauer juvenile yields were not affected. The cell density of P. luminescens in batch cultures was higher at 25 and 30[sup °]C than at growth temperatures of 35 and 37[sup °]C. In continuous culture, the bacterial growth was inhibited when the growth temperature reached 38[sup °]C. After approximately 60 h, the bacteria adapted to higher temperature and the growth rate increased again. When the temperature was further increased to 40[sup °]C, the bacterial growth was inhibited. [ABSTRACT FROM AUTHOR]

Laboratory studies were conducted to determine the lateral movement of Steinernema glaseri and Heterorhabditis bacteriophora in sand at 15, 20, 25 and 30°C in response to Galleria mellonella larvae. Lateral movement was assessed in 42.5 × 5 cm PVC tubes, constructed from 17 individual sections, with G. mellonella larvae placed on one end and the nematodes in the center. The proportion of the nematodes moving towards or away from the larvae at different temperatures was quantified at 8 h intervals. Although both species are reported to be cruisers, only S. glaseri responded to the host cues. The movement of the infective juveniles of both species increased significantly as temperature rose. The extraction efficiency of both species decreased at all temperatures with time. [ABSTRACT FROM AUTHOR]