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Entomopathogenic nematodes are used widely in biological insect control. Entomopathogenic nematodes can infect live insects as well as dead insects (i.e., they can act as scavengers). It is important to determine compatibility of entomopathogenic nematodes with other pest management tactics such as chemical insecticides. We hypothesized that chemical insecticides have negative impact on scavenging nematodes. According to our hypothesis, we first investigated the effects of direct exposure of Steinernema carpocapsae infectivity juveniles (IJs) to three chemical insecticides, cypermethrin, spinosad or diflubenzuron in terms of nematode survival and virulence. Subsequently, using the same chemicals, we tested the effects of insecticide-killed insects on scavenger nematode penetration efficiency, time of emergence and the number of nematode progeny. Prior to our study, the impact of pesticides on scavenger nematode fitness had not been studied. Fall webworm, Hyphantria cunea, and greater wax moth, Galleria mellonella, larvae were used as host insects. The survival rate of IJs after direct exposure was 83% for cypermethrin and 93-97% for the other insecticides and control. There were no significant differences in the survival and virulence of the nematodes after 24 h exposure to insecticides. The number of nematodes that invaded the insecticide-killed host was significantly higher in cypermethrin and spinosad treated groups and live H. cunea than in the diflubenzoron treated group and freeze-killed control. However, no significant differences were observed in time of emergence. Significantly more progeny IJs emerged from Spinosad-killed insects than the freeze-killed control. In conclusion, we discovered that the fitness of scavenging IJs is not diminished by insecticides in insect cadavers. In fact, in some cases the exposure to chemical insecticides may enhance virulence., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: In order to increase our knowledge on the susceptibility of entomopathogenic nematode (EPN) species to agrochemicals, the compatibility of the infective juveniles (IJs) of the EPN (Steinernema and Heterorhabditis) with eight chemical and bio-insecticides was investigated under laboratory conditions. The effect of direct IJ exposure to insecticides for 6 and 24 h was tested in a Petri dish at 15, 20 and 25 °C., Results: The study showed that S. carpocapsae and S. kraussei are sensitive to all tested insecticides. Steinernema feltiae is compatible with azadirachtin, toxin of Bacillus thuringiensis var. kurstaki and imidacloprid, while H. bacteriophora is sensitive only to abamectin and lufenuron. The percentage of IJs that survived was statistically the highest after 6 h at 15 °C (82%) and 20 °C (80%). At 25 °C (76%) it was statistically the lowest. After 24 h there were no statistically significant differences observed between 15 °C (55%) and 20 °C (55%), while at 25 °C, the statistically largest percentage of IJs (59%) survived., Conclusion: Based on our research, we conclude that compatibility is not only a species-specific, but also a strain-specific characteristic. Steinernema feltiae and H. bacteriophora are compatible with azadirachtin and pirimicarb and might offer a cost-effective alternative to pest control against different vegetable pests. © 2013 Society of Chemical Industry., (© 2013 Society of Chemical Industry.)

The survival and infectivity of infective juveniles (IJs) of three species of entomopathogenic nematodes, Steinernema carpocapsae Weiser, S. arenarium (Artyukhovsky) (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), were determined after exposure to different concentrations (250, 500, 1000 and 2000 ppm) of fipronil, an insecticide acting on the GABA receptors to block the chloride channel. Heterorhabditis bacteriophora was very tolerant to all concentrations of fipronil, with the highest mortality of 17% being observed at 2000 ppm of fipronil after 72 h exposure. Steinernema carpocapsae showed a similar response, with the highest mortality of 11.25% of IJs being observed after 72 h exposure to 2000 ppm of fipronil. Steinernema arenarium was, however, more sensitive to fipronil, and at 2000 ppm mortality rates of 94.6% and 100% were observed after 24 and 72 h, respectively. Fipronil had negligible effects on the infectivity of the three nematode species tested. The IJs which survive exposure to all concentrations of fipronil tested can infect and reproduce in Galleria larvae. The moderate effects on entomopathogenic nematodes of a lower fipronil concentration (250 ppm) and the field rates (12-60 ppm) of fipronil used as insecticide, suggest that direct mixing of entomopathogenic nematodes and fipronil at field rates is a viable integrated pest management option.

To develop a successful integrated pest management program for pest mole crickets (Orthoptera: Gryllotalpidae: Scapteriscus spp.), it is important to ascertain the compatibility of infective juveniles of insect parasitic nematodes and chemical insecticides. Aqueous solutions of five pesticides (acephate, bifenthrin, deltamethrin, fipronil, and imidacloprid) used in turfgrass to control mole crickets were tested for compatibility with Steinernema scapterisci Nguyen & Smart (Rhabditida: Steinernematidae) in the laboratory. Survival of S. scapterisci was >95% in solutions of acephate, bifenthrin, and imidacloprid. Infectivity of S. scapterisci in adult Scapteriscus vicinus Scudder was >60% in acephate and bifenthrin; however, infectivity was <40% in imidacloprid. The entomopathogenic nematode was compatible with most insecticides tested without significantly reduced survival or infectivity.