The influence of insecticides on the viability of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) under laboratory conditions
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.
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.
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