ENTOMOPATHOGENIC NEMATODES ASSOCIATION WITH SOIL- DWELLING BACTERIA: THE CASE OF STEINERNEMA FELTIAE

The symbiosis of entomopathogenic nematodes (EPNs) with bacteria in the genera Photorhabdus and Xenorhabdus is well known. However, other soil-dwelling bacteria can occasionally be isolated from EPNs collected from diseased larvae. Accordingly, through several studies, we have detected the presence of diverse bacterial species including isolates of Pseudomonas protegens and Serratia spp., in the body of different strains of the entomopathogenic nematode Steinernema feltiae. After documenting the presence of such bacteria inside the nematodes, both nematodes and EPN-associated bacteria were cultured, and bioassays were conducted to determine their potential against different insect targets. An isolate of P. protegens caused over 60% and 90% mortality of house fly and corn earworm larvae, respectively. These insecticidal effects were dose-dependent. The presence of the bacterium confers virulence to the nematode. According to our studies, it appears that these non-core bacteria can establish occasional or stable associations with S. feltiae. Key Words: Biological control, EPN, bacteria, symbiosis, Pseudomonas, soil, bioinsecticide.