Effect of moisture evaporation from diatomaceous earth pellets on storage stability of Steinernema glaseri

Induction of anhydrobiosis and storage stability of entomopathogenic nematodes are influenced by moisture availability. Decreasing moisture content in diatomaceous earth (DE) pellets containing the Steinernema glaseri NJ-43 strain and its effect on survival time and infectivity of the nematode were determined. Pelletisation was performed in a vortex mixer, using DE Celite® 209 as the desiccant material. Pellets were stored at room temperature (23?±?2°C) and high relative humidity (96–100%). Nematode survival and infectivity against last instar greater wax moth, Galleria mellonella, were tested daily. Initial average and average equilibrium moisture content in pellets were 66.7% and 13.6%, respectively, and the infective juveniles mean survival time was 8.8 days. A moisture transfer model based on diffusion and evaporation was evaluated to predict moisture fluctuations within the pellets. We concluded that 84% of variation in S. glaseri infectivity on G. mellonella larvae was explained by the survival of the nematode, whereas 52% of variation in S. glaseri survival was explained by the loss of moisture from the pellets. The moisture transfer model achieved 78% reliability in predicting moisture content and fluctuations. Therefore, the mechanisms of moisture diffusion and evaporation from the surface to the surrounding atmosphere contribute significantly to moisture loss from the pellets.     

Influences of host size and host species on theinfectivity and development of Heterorhabditismegidis (strain NLH-E87.3)

The infectivity, time to first emergence of infective juveniles (IJs), total number of IJs per insect and IJs body length of the entomopathogenic nematode Heterorhabditis megidis (strain NLH-E87.3) after development in larvae of two insect hosts, Galleria mellonella (greater wax moth) and Otiorhynchus sulcatus (vine weevil) was studied. At a dose of 30 IJs, larvae of G. mellonella show to be significantly more susceptible than O. sulcatus larvae. At a dose of one IJ, vine weevil larvae were more susceptible. The number of invading infective juveniles (IJs) increased with host size while the host mortality at a dose of one IJ decreased with the increase of host size. Time to first emergence was longer at a dose of one IJ per larva and increased with the increase of host size in both insect species. Reproduction of IJs differed between host species, host sizes and doses of nematodes. Generally, the IJs body size increased with an increasing host size. The longest infective juveniles were produced at the lowest IJ doses. Results are discussed in relation to the influence of different host species and their different sizes on the performance of H. megidis (strain NLH-E87.3) as a biological control agent.     

Efficacy of entomopathogenic nematodes against potato tuber moth,Phthorimaea operculella (Lepidoptera: Gelechiidae) under laboratory conditions

The susceptibility of potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) to native and commercial strains of entomopathogenic 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.     

Comparison of the methods applicable for the pathogenicity assessment of entomopathogenic nematodes

Single infective juveniles of Heterorhabditis bacteriophora, H. megidis (Nematoda: Heterorhabditidae), Steinernema arenarium, S. carpocapsae and S. feltiae (Nematoda: Steinernematidae) were used to infect single Galleria mellonella (Lepidoptera: Pyralidae) larvae. Four parameters of entomopathogenic nematodes pathogenicity were assessed: the mortality of insects, infectivity of nematodes, number of nematodes established per single G. mellonella, and degree of infective juveniles colonization (percent of infective juveniles which intestine was colonized by symbiotic bacteria). The accuracy, repeatability, and versatility for different species of EPNs in bioassay arenas were compared. Our modifications of the original methods yielded ~ 50% higher efficiency of infective juveniles in cell culture plates and > 20% higher efficiency in centrifuge test tubes. The efficiency of nematodes in cell culture plates (39–77%) was relatively low, especially in the case of Heterorhabditis spp. In the bioassay arena, infective juveniles migrated between cells. The results of our studies indicate that the pathogenicity of EPNs should be assessed in centrifuge test tubes. In these arenas, the infectivity of single IJs was ~ 90% for Heterorhabditis spp. and ~ 95% for Steinernema spp. The degree of colonization of the EPN isolates by symbiotic bacteria was in the range of 96–98%.     

Evaluation of entomopathogenic nematodes against the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae)

Infectivity of six entomopathogenic nematode (EPNs) species against Bactrocera oleae was compared. Similar infection levels were observed when third-instar larvae were exposed to infective juveniles (IJs) on a sand-potting soil substrate. When IJs were sprayed over naturally infested fallen olives, many larvae died within treated olives as well as in the soil; Steinernema feltiae caused the highest overall mortality of 67.9%. In addition, three laboratory experiments were conducted to optimize a time period for S. feltiae field application. (1) Abundance of fly larvae inside fallen olives was estimated over the 2006–2007 season with the highest number of susceptible larvae (3 mm and larger) per 100 olives being observed during December, 2006. (2) S. feltiae efficacy against fly larvae dropped to the soil post-IJ-application was determined. B. oleae added to the substrate before and after nematode application were infected at similar levels. (3) Effect of three temperature regimes (min–max: 10–27, 6–18, and 3–12 °C) corresponding to October through December in Davis, California on S. feltiae survival and infectivity was determined. After 8 weeks, the IJs at the 3–12 °C treatment showed the highest survival rate. However, the cold temperature significantly limited S. feltiae infectivity. Our results demonstrate that B. oleae mature larvae are susceptible to EPN infection both in the soil and within infested olives. Being the most effective species, S. feltiae may have the potential to suppress overwintering populations of B. oleae. We suggest that November is the optimal time for S. feltiae field application in Northern California.     

Natural enemies of natural enemies: the potential top‐down impact of predators on entomopathogenic nematode populations

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Mechanical production of pellets for the application of entomopathogenic nematodes: factors that determine survival time of Steinernema glaseri

Applications of infective juveniles (IJ) of entomopathogenic nematodes (EPN) formulated in pellets are still limited. This is principally due to limited advances in the technology of formulation. We aimed to develop a new method of mechanical formulation through material flow and to analyse its effect on the survival time of encapsulated EPN by varying the granular materials, the components of the aqueous suspension, the age of the nematodes and by applying a surface coating (C) to the pellet. Three-day-old and two-month-old Steinernema glaseri IJ were encapsulated with different proportions of diatomaceous earth (DE) and attapulgite clay (AC). The aqueous suspension containing the nematodes was prepared with double distilled water (DDW), varying proportions of Opuntia ficus-indica mucilage (OM) or gelatin (GL), and a sunflower oil surface treatment. The pellets were stored at an average room temperature of 23 ± 6°C. The best results were obtained with the following proportions: 100DE:0AC and 50DE:50AC, using the OM suspension, three-day-old nematodes and a surface C, which resulted in an average of 14 days survival time. These results confirmed that the nematodes do not die during mechanical encapsulation and that the age of the IJ as well as the loss of moisture during storage at room temperature were the factors that decreased the survival of encapsulated EPN. It was concluded that it is necessary to use neonate IJ and to reduce the moisture transfer rate in the granular structure in order to delay the desiccation of the encapsulated nematodes.     

Production of entomopathogenic nematodes in submerged monoxenic culture: A review

Monoxenic liquid culture is the most suitable technology for scaling up to industrial production of entomopathogenic nematodes (EPNs); however, the variability of the yield production remains a current problem in the process. The aim of this study was to analyze the parameters and criteria for EPN production in liquid culture based on scientific and technological knowledge from the last two decades. While experimental research has permitted the yield production of Heterorhabditis bacteriophora (362 × 10³ infective juveniles [IJs]/ml) and Steinernema carpocapsae (252 × 10³ IJs/ml), simultaneously, theoretical approaches have contributed to the understanding of the culture process, based on biological parameters of the bacterium–nematode complex and hydrodynamic and rheological parameters of the complex gas–liquid–solid system. Under this interdisciplinary research approach, bioprocess and biosystem engineering can contribute to design the various control strategies of the process variables, increase the productivity, and reduce the variability that until now distinguishes the in vitro production of EPNs by the liquid culture.     

Efficacy of two entomopathogenic nematodes Heterorhabditis bacteriophora and Steinernema carpocapsae for control of the leopard moth borer Zeuzera pyrina (Lepidoptera: Cossidae) larvae under laboratory conditions

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.     

Combined releases of entomopathogenic nematodes and the predatory mite Hypoaspis aculeifer to control soil-dwelling stages of western flower thrips Frankliniella occidentalis

The effect of the predatory miteHypoaspis aculeifer Canestrini (Acarina:Laelapidae) on soil-dwelling stages of thewestern flower thrips (WFT) Frankliniellaoccidentalis Pergande (Thysanoptera: Thripidae)and the influence of combined releases of H.aculeifer and two entomopathogenic nematodes(EPNs) Heterorhabditis bacteriophora Poinar(Rhabditida: Heterorhabditidae) (strain HK3,HK3) and Steinernema feltiae Filipjev(Rhabditida: Steinernematidae) (Nemaplus®,SFN) were investigated in pot trials usingseedlings of green beans (Phaseolus vulgarisL.). Ten H. aculeifer adults per pot and 400infective juveniles (IJs) cm^–2 soil, of the twoEPN strains were used. In comparison withuntreated control, H. aculeifer reduced theproportion of adult F. occidentalis emergenceby 46%, while SFN and HK3 led to a reductionin adult thrips emergence by 46% and 61%,respectively. Significant differences in adultWFT emergence were found between combinedtreatments of EPNs and H. aculeifer, andindividual applications of EPNs and/or H.aculeifer, with significantly lower adultthrips emergence in the combined treatments.These findings highlight the potential for acombined use of EPNs with H. aculeifer for thecontrol of soil-dwelling stages of thrips.     

Post-application of anti-desiccant agents improves efficacy of entomopathogenic nematodes in formulated host cadavers or aqueous suspension against diapausing codling moth larvae (Lepidoptera: Tortricidae)

Codling moth (CM), Cydia pomonella (L.) is the most serious pest of apple and other pome fruit worldwide. In temperate climates, diapausing cocooned larvae make up 100% of the population. Control of this stage would reduce or eliminate damage by first generation CM in late spring and early summer. Entomopathogenic nematodes (EPNs) are good candidates for control of CM in the cryptic habitats where the larvae overwinter. The two predominant limiting factors for EPNs are adequate moisture and temperatures below 15°C. Formulation that maintains moisture and enables survival of EPN infective juveniles (IJs) until they can infect overwintering larvae would significantly improve their utility for protection of apple, pear and walnut. In laboratory studies conducted in moist mulch (consisting of apple and conifer wood), Galleria mellonella (L.) larvae infected with Steinernema carpocapsae (Weiser), S. feltiae (Filipjev), or Heterorhabditis bacteriophora Poinar and coated with starch and clay, produced mean mortalities of 42, 88, and 24%, respectively in CM larvae. Mulched field plots treated with formulated S. carpocapsae- or S. feltiae-infected G. mellonella larvae, then followed by an application of wood flour foam as an anti-desiccant, resulted in 56 and 86% mortality, respectively. Comparative tests of aqueous suspensions of S. carpocapsae IJs applied to cardboard bands on apple tree trunks followed by water, fire retardant gel or foam resulted in 11, 35, and 85% respective mortalities. Identical tests with S. feltiae resulted in 20, 19, and 97% respective mortalities. Our research with cadaver formulations of EPNs in mulch and aqueous suspensions on tree trunks combined with anti-desiccant agents, demonstrated significant improvement in larvicidal activity for diapausing cocooned CM larvae.     

In vitro solid-state production of Steinernema innovationi with cost analysis

Low-cost mass production of entomopathogenic nematodes (EPNs) is an important prerequisite towards their successful commercialisation. This study evaluated six low-cost solid substrate media for in vitro mass production of Steinernema innovationi. Cost analysis was undertaken and an estimated retail price was calculated. This was then compared to the costs of commercial EPN products currently on the market. The highest yield of infective juveniles (IJs) was obtained from a medium containing a puree of house fly, Musca domestica, larvae?+?0.15?g canola oil, (781,678?±?221 IJs/5?g medium). This medium also had the lowest number of adults remaining in the medium and dead IJs (<10%) at the time of harvest (Day 28). The estimated retail price (R243.27 per 50 million IJs) for S. innovationi produced with our solid culture system was considerably lower than the market price for other Steinernema species products sold by E～nema, BASF corporation, Koppert, BioBest and Natural Insect Control. The production system developed in this study offers a competitive technology to produce EPN products without having to invest in large-scale liquid fermentation equipment, by using a relatively cheap production medium and simple solid culture growing conditions using Erlenmeyer flasks.     

Field Efficacy of Entomopathogenic Nematodes against the Sugar-beet Weevil Temnorhinus ( = Conorrhynchus ) mendicus Gyll. (Coleoptera: Curculionidae)

In 1992 and 1993, the field effectiveness of Heterorhabditis sp. (NL-HL81 strain), H. bacteriophora (HP 88 strain) and Steinernema carpocapsae ('All' strain) against the larvae of Temnorhinus mendicus Gyll. was assessed. The biological tests were compared with two chemical treatments (cypermethrin or deltamethrin) and one untreated control. In 1992, S. carpocapsae gave better results than Heterorhabditis sp. in reducing the percentage of infested roots, as compared with the untreated sample and the chemical one; similarly, the irrigated control gave the best results. In 1993, three concentrations of entomopathogenic nematodes (EPNs) were tested: 0.250 106 infective juveniles (IJs) m - 2, 0.125 106 IJs m - 2 and 0.075 106 IJs m - 2. The different numbers of EPNs did not give very different results from each other; however, H. bacteriophora at 0.075 106 IJs m - 2 was the least effective. In general, cypermethrin was more effective than deltamethrin, but one treatment with EPNs followed by irrigation was always more effective than two chemical applications.     

Entomopathogenic nematodes induce components of systemic resistance in plants: Biochemical and molecular evidence

Antagonism between entomopathogenic nematodes (EPNs) and plant-parasitic nematodes (PPNs) has been documented over the past two decades but its mechanism and ecological significance remain elusive. We investigated the effects of Steinernema carpocapsae and its symbiotic bacterium, Xenorhabdus nematophila applied to the potting medium on pyrogallol peroxidase (P-peroxidase), guaiacol peroxidase (G-peroxidase) and catalase activities in Hosta sp. and Arabidopsis thaliana leaves as components of induced systemic resistance. We found that P-peroxidase activity was significantly higher in the leaves from hosta plants treated with S. carpocapsae infective juveniles (IJs) and S. carpocapsae infected insect cadavers than in the leaves from the control plants 2 weeks after treatment. The G-peroxidase activity was significantly higher in S. carpocapsae infected cadaver and X. nematophila treatments 10 and 15 days after treatment (DAT) and in S. carpocapsae IJs treatment 5 and 15 DAT. The catalase activity in hosta leaves was significantly higher in S. carpocapsae infected cadaver and X. nematophilus treatments compared with the control 5 and 15 DAT and in S. carpocapsae IJs treatment 5 and 10 DAT. Further, the catalase activity in A. thaliana leaves was significantly higher in S. carpocapsae IJs treatment than in the control 7 DAT. We also determined the effects of S. carpocapsae infected cadavers and S. carpocapsae IJs on PR1-gene expression in transgenic A. thaliana leaves through GUS (β-glucuronidase) activity assay and found that the PR1-gene was expressed in leaves from all treatments except the control. Thus, we conclude that the EPNs and their symbiotic bacteria can induce systemic resistance in plants which may explain the elusive antagonistic effect of EPNs on PPNs.     

Host influences on the pathogenicity of Heterorhabditis megidis

The infectivity of infective juveniles(IJs) of Heterorhabditis megidis (strain NLH-E87.3) produced on small, medium and large larvae ofGalleria mellonella, and on medium and largelarvae of Otiorhynchus sulcatus was tested underlaboratory conditions against G. mellonella andO. sulcatus larvae. Infective juvenilesoriginating from small G. mellonella exposed toan initial dose of one IJ were more infectious thanthose from small cadavers exposed to a dose of 30 IJs.Independent of the initial inoculum size, IJs fromsmall cadavers of G. mellonella were moreinfectious than those from medium and large cadavers.At a dose of one IJ per larva, IJs originating frommedium size O. sulcatus cadavers were moreinfective against G. mellonella than againstO. sulcatus larvae. Large G. mellonellalarvae were less susceptible to all IJ batches thanmedium and small sized larvae.     

Effect of Soil Texture and Moisture on the Activity of Entomopathogenic Nematodes Against Female Boophilus annulatus Ticks

Soil texture, chemistry and moisture have a profound effect upon the activity and persistence of entomopathogenic nematodes (EPNs). Whereas nematodes’ natural habitat is within the soil, ticks and other arthropod pests prefer to stay on the soil surface and under stones or leaf litter; they spend much of their life cycle in the humid environment of the soil upper layer, therefore consideration of the effect of the soil environment on nematode activity is a pre-requisite for the sucessful use of EPNs against arthropod pests. In the present study we investigated the effects of soil type, and humidity on various nematode strains and on their effectiveness against ticks. Many infective juveniles (IJs) of Steinernema carpocapsae and S. riobrave were found in the uppermost soil layer whereas the heterorhabditid strains were almost absent from the upper 6 cm of the soil profile. The IJs of S. feltiae, and the S. carpocapsae strain S-20, exhibited an intermediate behavior. It was found that the activity of IJs of S. carpocapsae in the soil upper layer (1 cm depth) was strongly affected by soil type: the greatest number of IJs were recorded from sandy loam soil; less were found in the lighter soils – ‘Marine sand’ and ‘Calcareous sandstone’ – and only very few were recovered from heavy soils. Strikingly, even when the soil moisture was low and the number of nematodes found in the upper layer correspondingly low, tick mortality remained high. The results demonstrate: (a) the possible use of the nematodes as an anti-tick agent; (b) the importance of knowing the exact interaction of nematodes with the immediate environment of the pest, in order to optimize the pest-control activity of the nematode.     

Infectivity of entomopathogenic nematode Steinernema carpocapsae Pocheon strain (Nematoda: Steinernematidae) on the green peach aphid Myzus persicae (Hemiptera: Aphididae) and its parasitoids

Infectivity of entomopathogenic nematode (EPN) Steinernema carpocapsae Pocheon strain on the green peach aphid Myzus persicae and its parasitic wasps (e.g., Aphidius colemani, Aphidius gifuensis and Diaeretiella rapae) was evaluated under laboratory conditions. Infective juveniles (IJs) of S. carpocapsae Pocheon strain had low infectivity against nymph and adult stages of M. persicae, showing 2% and 6.7% of mortality, respectively. Application of the EPNs had little effect on mummies caused by the three parasitoid species, allowing them to remain intact. No IJ invaded the host, regardless of EPN application rate. The parasitoid emergence from mummies ranged from 80% to 85% in the presence of EPN while 79–86% was recorded in the absence of EPN. However, the presence of the IJs reduced oviposition by the three parasitoid species, decreasing the rate up to 59% when the nematodes were applied before parasitoid release, while little difference in oviposition was observed when nematodes were applied after parasitoid release.     

Behavioural and physiological responses of infective juveniles of the entomopathogenic nematode Heterorhabditis to desiccation

Infective juveniles (IJs) of entomopathogenic nematodes (EPNs) are susceptible to a wide variety of environmental factors, including desiccation, which limit their usefulness as biocontrol agents. Although EPNs can be subjected to a gradual loss of water in their natural environment they are not full anhydrobiotes, being able to survive only moderate levels of desiccation at high relative humidities (rh). We investigated the desiccation tolerance of IJs of several Heterorhabditisspecies and strains when exposed to fast and slow desiccation regimes. We also investigated the behavioural and biochemical responses of Heterorhabditis IJs when exposed to 98% rh for 4 days. IJs of H. megidis UK211 (but not IJs of H. indica) aggregate into large clumps when desiccated at high rh, but unlike Steinernema spp., neither H. megidis nor H. indica IJs showed any tendency to coil. Preincubation of H. megidis UK211 IJs at high (98%) rh enhances their ability to survive for 150 min at 57% rh. We show that preincubation of H. megidis and H. indica at 98% rh induces the synthesis of glycerol but not of trehalose, whereas identical preincubation conditions do induce trehalose synthesis in Steinernema carpocapsae and Aphelenchus avenae. The biosynthesis of glycerol rather than trehalose by IJs of two species of Heterorhabditis in response to moderate levels of desiccation indicates that Heterorhabditis is unlikely to have the necessary metabolic responses to desiccation required to enable it to enter into a fully anhydrobiotic state.     

Pathogenicity of Heterorhabditis nematodes isolated from north-western Himalaya against the larvae of Plutella xylostella (L.) (Lepidoptera: Plutellidae)

The efficacy of three entomopathogenic nematodes (Heterorhabditis spp.), from north western Himalaya, India was studied against the diamondback moth, Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae), under laboratory conditions. The larvae were exposed to 10, 20, 30 and 40 infective juveniles (IJs) of each nematode species for different time periods and they were found to be susceptible to all the EPNs tested. However, the susceptibility of larvae to nematode infection varied according to the dosages of IJs and their exposure periods. The efficacy of these indigenous entomopathogenic nematodes was also evaluated against the commercially available entomopathogenic nematode H. indica. An indigenous isolate, H. bacteriophora (HRJ), along with the commercial isolate H. indica recorded 100.0% mortality of insect larvae in 96 h exposure time against third instar larvae of P. xylostella. However, it was noticed that with the advancement of larval stage its mortality rate reduces and vice versa with the exposure period. All the tested nematode species were also found to reproduce within the host and produced infective juveniles. In conclusion, the evidence obtained in this study suggests that all the three indigenous EPN species are virulent enough to produce 100% mortality of larvae of P. xylostella. These EPN species thus have potential for the management of P. xylostella under integrated management practices.     

Effect of insect cadaver desiccation and soil water potential during rehydration on entomopathogenic nematode (Rhabditida: Steinernematidae and Heterorhabditidae) production and virulence

We examined the influence of insect cadaver desiccation on the virulence and production of entomopathogenic nematodes (EPNs), common natural enemies of many soil-dwelling insects. EPNs are often used in biological control, and we investigated the feasibility of applying EPNs within desiccated insect cadavers. Desiccation studies were conducted using the factitious host, Galleria mellonella (Lepidoptera: Pyralidae, wax moth larvae) and three EPN species (Heterorhabditis bacteriophora ‘HB1’, Steinernema carpocapsae ‘All’, and Steinernema riobrave). Weights of individual insect cadavers were tracked daily during the desiccation process, and cohorts were placed into emergence traps when average mass losses reached 50%, 60%, and 70% levels. We tracked the proportion of insect cadavers producing infective juveniles (IJs), the number and virulence of IJs produced from desiccated insect cadavers, and the influence of soil water potentials on IJ production of desiccated insect cadavers. We observed apparent differences in the desiccation rate of the insect cadavers among the three species, as well as apparent differences among the three species in both the proportion of insect cadavers producing IJs and IJ production per insect cadaver. Exposure of desiccated insect cadavers to water potentials greater than −2.75 kPa stimulated IJ emergence. Among the nematode species examined, H. bacteriophora exhibited lower proportions of desiccated insect cadavers producing IJs than the other two species. Desiccation significantly reduced the number of IJs produced from insect cadavers. At the 60% mass loss level, however, desiccated insect cadavers from each of the three species successfully produced IJs when exposed to moist sand, suggesting that insect cadaver desiccation may be a useful approach for biological control of soil insect pests.