Evaluation of hydraulic,pneumatic and mechanical agitation for the spray application of Steinernema carpocapsae (Rhabditida: Steinernematidae)

The application of entomopathogenic nematodes (EPN) is generally done using standard spray application techniques. However, in contrast to chemical pesticides, these biological antagonists must remain viable during and after the application process. For the application of EPN, a good agitation system is indispensable as the nematodes tend to sediment fast in a spray tank without agitation. Three agitation systems, viz. mechanical, pneumatic and hydraulic agitation were tested for their ability to keep Steinernema carpocapsae (Rhabditida: Steinernematidae) suspended in an undamaged way. Hydraulic agitation was tested using a centrifugal and a diaphragm pump. Nematode damage was quantified based on viability and infectivity of the EPN. The ability of the agitation system to keep the nematodes in suspension was examined by comparing the nematode concentration observed in the samples taken at different agitation times. Only the hydraulic agitation using the centrifugal pump damaged the nematodes. After 120 min of recirculation, only 19.3% of the nematodes survived. Infectivity was even reduced to 0%. An additional experiment revealed that the temperature rise, from 21.7 to 45.4°C, was responsible for the observed nematode damage. The concentration measurements showed that the pneumatic agitation was unstable. Agitation during 120 min using the other agitation systems resulted in a significant loss of nematodes at 15 cm above the spray tank bottom. In conclusion, mechanical and hydraulic agitation using a diaphragm pump can be recommended when S. carpocapsae is applied, although attention should be paid to possible nematode loss during application.     

Pathogenicity of Two Species of Entomopathogenic Nematodes Against the Greenhouse Whitefly,Trialeurodes vaporariorum (Hemiptera: Aleyrodidae), in Laboratory and Greenhouse Experiments

The greenhouse whitefly Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) is a polyphagous pest in greenhouse crops. The efficacy of two entomopathogenic nematodes (EPN), Steinernema feltiae and Heterorhabditis bacteriophora, as biological control agents against T. vaporariorum was evaluated using two model crops typical of vegetable greenhouse productions: cucumber and pepper. Laboratory tests evaluated adults and second nymphal instars for pest susceptibility to different EPN species at different concentrations of infective juveniles (IJ; 0, 25, 50, 100, 150, 200, and 250 IJ per cm²); subsequent greenhouse trials against second nymphal instars on cucumber and pepper plants evaluated more natural conditions. Concentrations were applied in combination with Triton X-100 (0.1% v/v), an adjuvant for increasing nematode activity. In laboratory studies, both life stages were susceptible to infection by the two nematode species, but S. feltiae recorded a lower LC₅₀ than H. bacteriophora for both insect stages. Similarly, in greenhouse experiments, S. feltiae required lower concentrations of IJ than H. bacteriophora to reach the same mortality in nymphs. In greenhouse trials, a significant difference was observed in the triple interaction among nematode species × concentration × plant. Furthermore, the highest mortality rate of the second nymphal instars of the T. vaporariorum was obtained from the application of S. feltiae concentrated to 250 IJ/cm² on cucumber (49 ± 1.23%). The general mortality caused by nematodes was significantly higher in cucumber than in pepper. These promising results support further investigation for the optimization of the best EPN species/concentration in combination with insecticides or adjuvants to reach a profitable control of this greenhouse pest.     

Control of the Oriental Fruit Moth, Grapholita molesta, Using Entomopathogenic Nematodes in Laboratory and Fruit Bin Assays

The oriental fruit moth (OFM), Grapholita molesta (Busck), which is among the most important insect pests of peaches and nectarines, has developed resistance to a wide range of insecticides. We investigated the ability of the entomopathogenic nematodes (EPN) Steinernema carpocapsae (Weiser), S. feltiae (Filipjev), S. riobrave (Cabanillas et al.), and Heterorhabditis marelatus (Liu and Berry) to control OFM under laboratory and fruit bin conditions. At a dosage of 10 infective juveniles (IJ)/cm² in the laboratory, S. carpocapsae caused 63%, S. feltiae 87.8%, S. riobrave 75.6%, and H. marelatus 67.1% OFM mortality. All four nematode species caused significant OFM larval mortality in comparison to the nontreated controls. Steinernema feltiae was used for the bin assays due to the higher OFM mortality it caused than the other tested EPN species and to its ability to find OFM under cryptic environments. Diapausing cocooned OFM larvae in miniature fruit bins were susceptible to IJ of S. feltiae in infested corner supports and cardboard strips. Treatment of bins with suspensions of 10 or 25 S. feltiae IJ/ml water with wetting agent (Silwet L77) resulted in 33.3 to 59% and 77.7 to 81.6% OFM mortality in corner supports and cardboard strips, respectively. This paper presents new information on the use of EPN, specifically S. feltiae, as nonchemical means of OFM control.     

The effect of agitation system, temperature of the spray liquid, nematode concentration, and air injection on the viability of Heterorhabditis bacteriophora

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.     

Susceptibility of Queensland fruit fly,Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), to entomopathogenic nematodes

Queensland fruit fly, Bactrocera tryoni (Froggatt), is the economically most significant Australian tephritid pest species with a large invasion potential, yet relatively little work on its biological control has been undertaken. Entomopathogenic nematodes (EPNs) are of potential interest for control of this fruit fly species as it pupates in the soil. Specifically, the pre-pupal stage of B. tryoni may present a unique window for EPN application, as fully developed larvae drop from infested fruit to the soil for pupation. For the first time, we tested the capacity of three EPN species with different foraging strategies, Steinernema feltiae, Steinernema carpocapsae and Heterorhabditis bacteriophora, to cause larval and pupal mortality in B. tryoni across a range of EPN concentrations (50, 100, 200, 500 and 1000 infective juveniles IJs cm^-2), substrate moisture (10, 15, 20 and 25% w/v) and temperatures (15, 20, 25 and 30 °C). We found that all EPN species tested caused environment and density dependent mortality in the third larval instar while pupae were not affected. Steinernema feltiae caused high mortality across different IJ concentrations and over a wider moisture and temperature range than the other two EPN species. High mortality caused by S. carpocapsae and H. bacteriophora was more limited to high IJ concentrations and a narrower moisture and temperature range. Our findings highlight the potential of EPNs for the control of B. tryoni and warrant further laboratory and field experiments to evaluate their efficacy under the wide environmental conditions that B. tryoni can occur in.     

Compatibility of Soil Amendments with Entomopathogenic Nematodes

The impact of inorganic and organic fertilizers on the infectivity, reproduction, and population dynamics of entomopathogenic nematodes was investigated. Prolonged (10- to 20-day) laboratory exposure to high inorganic fertilizer concentrations inhibited nematode infectivity and reproduction, whereas short (1-day) exposures increased infectivity. Heterorhabditis bacteriophora was more sensitive to adverse effects than were two species of Steinernema. In field studies, organic manure resulted in increased densities of a native population of Steinernema feltiae, whereas NPK fertilizer suppressed nematode densities regardless of manure applications. Inorganic fertilizers are likely to be compatible with nematodes in tank mixes and should not reduce the effectiveness of nematodes used for short-term control as biological insecticides, but may interfere with attempts to use nematodes as inoculative agents for long-term control. Organic manure used as fertilizer may encourage nematode establishment and recycling.     

Harmful effects of mustard bio-fumigants on entomopathogenic nematodes

Mustard (Brassica and Sinapis spp.) green manures tilled into the soil preceding potato crops act as bio-fumigants that are toxic to plant–parasitic nematodes, providing an alternative to synthetic soil fumigants. However, it is not known whether mustard green manures also kill beneficial entomopathogenic nematodes (EPNs) that contribute to the control of pest insects. We used sentinel insect prey (Galleria mellonella larvae) to measure EPN infectivity in Washington State (USA) potato fields that did or did not utilize mustard green manures. We found a trend toward lower rates of EPN infection in fields, where mustard green manures were applied, compared to those not receiving this cultural control method. In a series of bioassays we then tested whether the application of two mustard (Brassica juncea) cultivars, differing in glucosinolate levels, disrupted the abilities of a diverse group of EPN species to infect insect hosts. Mustard-exposure trials were conducted first in laboratory arenas where EPNs were exposed to mustard extracts suspended in water, and then in larger microcosms in the greenhouse where EPNs were exposed to green manure grown, chopped, and incorporated into field soil. In all trials we used G. mellonella larvae as hosts and included multiple EPN species in the genera Steinernema (Steinernema carpocapsae, Steinernema feltiae, Steinernema glaseri, and Steinernema riobrave) and Heterorhabditis (Heterorhabditis bacteriophora, Heterorhabditis marelatus, and Heterorhabditis megidis). In the laboratory, EPN infection rates were lower in arenas receiving mustard extracts than the control (water), and lower still when EPNs were exposed to extracts from plants with high versus low glucosinolate levels. Results were nearly identical when mustard foliage was soil-incorporated into greenhouse microcosms, except that the negative effects of mustards on EPNs developed more slowly in soil. Significantly, in arenas of both types one EPN species, S. feltiae, appeared to be relatively unaffected by mustard exposure. Together, our results suggest that the use of mustard bio-fumigants for the control of plant–parasitic nematodes has the potential to interfere with the biocontrol of insect pests using EPNs. Thus, it may be difficult to combine these two approaches in integrated pest management programs.     

Pathogenic effect of entomopathogenic nematode-bacterium complexes on terrestrial isopods

In this study, we evaluated the effect of entomopathogenic nematodes (EPNs) Steinernema carpocapsae, Steinernema feltiae and Heterorhabditis bacteriophora, symbiotically associated with bacteria of the genera Xenorhabdus or Photorhabdus, on the survival of eight terrestrial isopod species. The EPN species S. carpocapsae and H. bacteriophora reduced the survival of six isopod species while S. feltiae reduced survival for two species. Two terrestrial isopod species tested (Armadillidium vulgare and Armadillo officinalis) were found not to be affected by treatment with EPNs while the six other isopod species showed survival reduction with at least one EPN species. By using aposymbiotic S. carpocapsae (i.e. without Xenorhabdus symbionts), we showed that nematodes can be isopod pathogens on their own. Nevertheless, symbiotic nematodes were more pathogenic for isopods than aposymbiotic ones showing that bacteria acted synergistically with their nematodes to kill isopods. By direct injection of entomopathogenic bacteria into isopod hemolymph, we showed that bacteria had a pathogenic effect on terrestrial isopods even if they appeared unable to multiply within isopod hemolymphs. A developmental study of EPNs in isopods showed that two of them (S. carpocapsae and H. bacteriophora) were able to develop while S. feltiae could not. No EPN species were able to produce offspring emerging from isopods. We conclude that EPN and their bacteria can be pathogens for terrestrial isopods but that such hosts represent a reproductive dead-end for them. Thus, terrestrial isopods appear not to be alternative hosts for EPN populations maintained in the absence of insects.     

Improving foliar applications of entomopathogenic nematodes by selecting adjuvants and spray nozzles

This study explores the influence of a selection of adjuvants and of three different nozzle sizes on the foliar application of entomopathogenic nematodes (EPNs). Two EPN species were studied: Steinernema feltiae and Steinernema carpocapsae. A viability test of EPNs suspended in different solutions of adjuvants showed that all selected alcohol ethoxylates and an alkyl polysaccharide have an immobilising effect on the selected nematode species. In a sedimentation test, xanthan gum proved to be the only adjuvant in a broad selection, capable of delaying sedimentation of EPNs in suspension. Without xanthan gum, sedimentation of S. carpocapsae and S. feltiae was noticeable after 20 and 10 minutes, respectively. When xanthan gum (0.3 g/L) was added to the suspension, no signs of sedimentation were noticed after 20 minutes with both EPN species. An ISO 02 flat fan nozzle can clog when spraying S. carpocapsae. A deposition test determined that an ISO 04 standard flat fan nozzle provides a higher relative deposition on cauliflower leaves and is therefore a better nozzle choice than the bigger ISO 08 standard flat fan nozzle for spraying S. carpocapsae. The addition of a spreading agent improved the deposition of S. carpocapsae. Adding xanthan gum to the EPN-spreading agent mixtures did not further improve deposition.     

Viability and Virulence of Entomopathogenic Nematodes Exposed to Ultraviolet Radiation

Entomopathogenic nematodes (EPNs) can be highly effective biocontrol agents, but their efficacy can be reduced due to exposure to environmental stress such as from ultraviolet (UV) radiation. Our objectives were to 1) compare UV tolerance among a broad array of EPN species, and 2) investigate the relationship between reduced nematode viability (after exposure to UV) and virulence. Nematodes exposed to a UV radiation (254 nm) for 10 or 20 min were assessed separately for viability (survival) and virulence to Galleria mellonella. We compared 9 different EPN species and 15 strains: Heterorhabditis bacteriophora (Baine, fl11, Oswego, and Vs strains), H. floridensis (332), H. georgiana (Kesha), H. indica (HOM1), H. megidis (UK211), Steinernema carpocapsae (All, Cxrd, DD136, and Sal strains), S. feltiae (SN), S. rarum (17C&E), and S. riobrave (355). In viability assessments, steinernematids, particularly strains of S. carpocapsae, generally exhibited superior UV tolerance compared with the heterorhabditids. However, some heterorhabditids tended to be more tolerant than others, e.g., H. megidis and H. bacteriophora (Baine) were most susceptible and H. bacteriophora (Vs) was the only heterorhabditid that did not exhibit a significant effect after 10 min of exposure. All heterorhabditids experienced reduced viability after 20 min exposure though several S. carpocapsae strains did not. In total, after 10 or 20 min exposure, the viability of seven nematode strains did not differ from their non-UV exposed controls. In virulence assays, steinernematids (particularly S. carpocapsae strains) also tended to exhibit higher UV tolerance. However, in contrast to the viability measurements, all nematodes experienced a reduction in virulence relative to their controls. Correlation analysis revealed that viability among nematode strains is not necessarily related to virulence. In conclusion, our results indicate that the impact of UV varies substantially among EPNs, and viability alone is not a sufficient measure for potential impact on biocontrol efficacy as other characters such as virulence may be severely affected even when viability remains high.     

Entomopathogenic Nematode Production and Application Technology

Production and application technology is critical for the success of entomopathogenic nematodes (EPNs) in biological control. Production approaches include in vivo, and in vitro methods (solid or liquid fermentation). For laboratory use and small scale field experiments, in vivo production of EPNs appears to be the appropriate method. In vivo production is also appropriate for niche markets and small growers where a lack of capital, scientific expertise or infrastructure cannot justify large investments into in vitro culture technology. In vitro technology is used when large scale production is needed at reasonable quality and cost. Infective juveniles of entomopathogenic nematodes are usually applied using various spray equipment and standard irrigation systems. Enhanced efficacy in EPN applications can be facilitated through improved delivery mechanisms (e.g., cadaver application) or optimization of spray equipment. Substantial progress has been made in recent years in developing EPN formulations, particularly for above ground applications, e.g., mixing EPNs with surfactants or polymers or with sprayable gels. Bait formulations and insect host cadavers can enhance EPN persistence and reduce the quantity of nematodes required per unit area. This review provides a summary and analysis of factors that affect production and application of EPNs and offers insights for their future in biological insect suppression.     

Effect of Host Age and Nematode Strain on Susceptibility of Spodoptera frugiperda to Steinernema feltiae

Median lethal concentrations (LC₅₀) were determined for four nematode populations (two strains of Steinernema feltiae, a S. feltiae hybrid, and S. bibionis) against fifth-instar fall armyworm (Spodoptera frugiperda) larvae and for the most virulent of these nematodes against different instars and stages of the insect. Based on lack of overlap of 95% fiducial limits, there were significant differences in virulence among the four nematodes. The LC₅₀ ranged from 7.6 to 33.3 nematodes/ 0.7 ml water, and slopes of the log dose-probit regression lines were similar except for the S. feltiae All strain. First-instar fall armyworms suffered virtually 100% mortality from the S. feltiae Mexican strain at 1.0 nematode/0.7 ml, and LC₅₀ were 2.3 and 7.9 nematodes/0.7 ml in third-instar and fifth-instar larvae, respectively. Pupae had 7-20% mortality at doses ranging from 30 to 60 nematodes/0.7 ml.     

Screening Spanish isolates of steinernematid nematodes for use as biological control agents through laboratory and greenhouse microcosm studies

Entomopathogenic nematodes (EPNs) are one of the best non-chemical alternatives for insect pest control, with native EPN strains that are adapted to local conditions considered to be ideal candidates for regional biological control programs. Virulence screening of 17 native Mediterranean EPN strains was performed to select the most promising strain for regional insect pest control. Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) Rioja strain produced 7%, 91% and 33% larval mortality for the insects Agriotes sordidus (Illiger) (Coleoptera: Elateridae), Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), respectively, and was selected as the most promising strain. The S. feltiae Rioja strain-S. littoralis combination was considered the most suitable to develop the Rioja strain as a biocontrol agent for soil applications. The effect of soil texture on the virulence of the Rioja strain against S. littoralis was determined through dose-response experiments. The estimated LC₉₀ to kill larvae in two days was 220, 753 and 4178 IJs/cm² for soils with a clay content of 5%, 14% and 24%, respectively, which indicates that heavy soils produced negative effects on the virulence of the Rioja strain. The nematode dose corresponding to the LC₉₀ for soils with a 5% and 14% clay content reduced insect damage to Capsicum annuum Linnaeus (Solanales: Solanaceae) plants under greenhouse microcosm conditions. The results of this research suggest that an accurate characterization of new EPN strains to select the most suitable combination of insect, nematode and soil texture might provide valuable data to obtain successful biological control under different ecological scenarios in future field applications.     

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%.     

Soil Applications of Steinernematid and Heterorhabditid Nematodes for Control of Colorado Potato Beetles,Leptinotarsa decemlineata (Say)

Three strains of Steinernema feltiae Filipjev (All, Mexican, and Breton strains) and one of Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) were evaluated for their potential to control Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), larvae and pupae in the soil. In laboratory studies, H. heliothidis and S. feltiae (Mexican strain) produced the highest mortality (6 days posttreatment) of CPB when applied to the surface of a soil column containing mature CPB larvae 5 cm below. Mortality ranged from 80 to 90% at rates of 79-158 nematodes/cm². Similar results were seen in a field microplot study with all four nematodes; S. feltiae (Mexican strain) and H. heliothidis were most effective. Adult CPB emergence was reduced 86.5-100% after application of 31-93 H. heliothidis/cm² and 88.4-100% with 93-155 S. feltiae (Mexican strain)/cm². The All strain of S. feltiae was moderately effective (ca. 80% reduction at 93-155 nematodes/cm²), while the Breton strain was ineffective (< 40% reduction at 155 nematodes/cm²). In small plots of potatoes enclosed in field cages, application of H. heliothidis and S. feltiae (Mexican strain) at rates of 93-155 nematodes/cm² before larval CPB burial in the soil resulted in 66-77% reduction in adult CPB emergence. Soil applications of these nematodes show potential for biological control of CPB.     

Isolation and identification of entomopathogenic nematodes and their symbiotic bacteria from Hérault and Gard (Southern France)

Isolation and identification of native nematode-bacterial associations in the field are necessary for successful control of endemic pests in a particular location. No study has yet been undertaken to recover and identify EPN in metropolitan France. In the present paper, we provide results of a survey of EPN and their symbiotic bacteria conducted in Hérault and Gard regions in Southern France. Molecular characterization of isolated nematodes depicted three different Steinernema species and one Heterorhabditis species, H. bacteriophora. Steinernema species recovered were identified as: S. feltiae and S. affine and an undescribed species. Xenorhabdus symbionts were identified as X. bovienii for both S. feltiae and S. affine. Phylogenetic analysis placed the new undescribed Steinernema sp. as closely related to S. arenarium but divergent enough to postulate that it belongs to a new species within the “glaseri-group”. The Xenorhabdus symbiont from this Steinernema sp. was identified as X. kozodoii. All Heterorhabditis isolates recovered were diagnosed as H. bacteriophora and their bacterial symbionts were identified as Photorhabdus luminescens. Molecular characterization of these nematodes enabled the distinction of two different H. bacteriophora strains. Bacterial symbiontic strains of these two H. bacteriophora strains were identified as P. luminescens ssp. kayaii and P. luminescens ssp. laumondii.     

Infectivity of Steinernema carpocapsae and S. feltiae to Larvae and Adults of the Hazelnut Weevil,Curculio nucum: Differential Virulence and Entry Routes

We investigated the existing susceptibility differences of the hazelnut weevil, Curculio nucum L. (Coleoptera:, Curculionidae) to entomopathogenic nematodes by assessing the main route of entry of the nematodes, Steinernema carpocapsae strain B14 and S. feltiae strain D114, into larvae and adult insects, as well as host immune response. Our results suggested that S. carpocapsae B14 and S. feltiae D114 primarily entered adult insects and larvae through the anus. Larvae were more susceptible to S. feltiae D114 than S. carpocapsae B14 and adults were highly susceptible to S. carpocapsae B14 but displayed low susceptibility to S. feltiae D114. Penetration rate correlated with nematode virulence. We observed little evidence that hazelnut weevils mounted any cellular immune response toward S. carpocapsae B14 or S. feltiae D114. We conclude the differential susceptibility of hazelnut weevil larvae and adults to S. carpocapsae B14 and S. feltiae D114 primarily reflected differences in the ability of these two nematodes to penetrate the host.     

Fungal conidia distribution on chrysanthemum: varying spray parameters

The conidial deposition of BotaniGard® 22WP on chrysanthemum plants was assessed. Assessments were conducted on stationary and moving applications using different spray nozzles, application angles and tank pressures. In addition, the spray time and distance from the target plant were included. Conidial deposition was greater on the upper canopy of the plants and the upper sides of the leaves. The nozzle type, spray angle, and distance from the target plant had the most significant effects on conidial distribution. The optimal spray nozzles were found to be HC-22 and FAN-1, which provided the best coverage of both the plants in general, and on the lower surfaces of the leaves.     

Entomopathogenic nematodes control Plum Sawflies (Hoplocampa minuta and H. flava)

Plum sawflies are among the most damaging pests of European plum. Current control strategy implies insecticide application. Three species of entomopathogenic nematodes (EPN), Steinernema feltiae Filipjev, S. carpocapsae Weiser and Heterorhabditis bacteriophora Poinar were tested under laboratory and field conditions to assess effectiveness against larval and adult stages. Laboratory tests resulted in up to 100% mortality of last instar larvae before construction of a cocoon. However, the nematodes were not able to penetrate the cocoon. Foliar application did not result in plum sawflies larvae infestation by EPNs. Under field conditions, the nematodes reduced the number of emerging adults by application against sawfly larvae in the previous year before migration into the soil for overwintering by 62%–92%. Application of the nematodes against adults just before their anticipated emergence resulted in reduction of fruit infestation up to 100%. Mean results of 5 trials using caged trees were 47.8% with S. feltiae, 56.3% with S. carpocapsae and 62.9% with H. bacteriophora. In open field trails, control of adults obtained with S. feltiae at 0.5 million nematodes/m² was 98.2 and 67.8% and at 0.25 million m⁻² 41.7 and 41.2%. Forecasting adult emergence and optimal soil moisture conditions are essential for success of the nematode application.