Compatibility of entomopathogenic nematode Heterorhabditis indica (Nematoda: Heterorhabditidae) with agrochemicals used in the rice ecosystem.

Abstract

The compatibility of entomopathogenic nematode Heterorhabditis indica with 14 insecticides, 6 fungicides and 7 herbicides commonly used in rice ecosystems was investigated under laboratory conditions. The effect of these chemicals on nematode viability and virulence upon direct exposure to chemicals at recommended concentrations was studied. H. indica was tolerant to most of the insecticides tested with less than 10% nematode mortality observed in all insecticides except monocrotophos (19.5%) and cartap hydrochloride (100%) after 72 h of exposure. Less than 10% mortality was observed in all fungicides tested except tricyclazole (14.5%) and carbendazium +mancozeb (21.5%) after 72 h of exposure to fungicides. Nematode mortality in case of herbicides ranged from 3.5% to 18% after 72 h of exposure. Insecticides showed only a marginal effect on the virulence of H. indica. Mortality of Galleria mellonella larvae in all the treatments was more than 90% except in treatments with chlorpyrifos (80%) and monocrotophos (60%) treated infective juveniles after 48 h. These results show that H. indica is compatible with all the tested agrochemicals except monocrotophos and cartap hydrochloride among insecticides, tricyclazole and carbendazium+mancozeb among fungicides, and pendimethalin among herbicides.