The toxicity effect of five insecticides (Dipel 2x, Radiant, Proclaim, Aphox and Coragen) on two species of
entomopathogenic nematodes (EPNs) (Heterorhabditis bacteriophora BA1 and Steinernema carpocapsae BA2), were
evaluated under laboratory conditions at different concentrations 100%, 50% and 25% of field rates (FR). Moreover, the
virulence of insecticide-treated EPNs against the lst nymphal instar of the greater wax moth Galleria mellonella L.
(Lepidoptera: Pyralidae) was also evaluated. Data indicated that all insecticides showed negative effect on the tested
infective juveniles (IJs) of EPNs and the percentages of mortality were in order of H. bacteriophora BA1>S.
carpocapsae BA2 and were concentration-dependent; significant differences existed between untreated (control) and
insecticide treatments EPNs. Proclaim insecticide recorded the highest mortality rate in EPNs at all tested
concentrations 24, 48 and 72 hours post treatment. Regarding the effect of tested insecticides on the virulence and the
reproductive capacity of treated EPNs, data indicated that the ability of insecticide-treated EPNs to locate and infect
larvae of G. mellonella decreased after exposure to insecticide and consequently reproductive capacity of EPNs was
significantly reduced.