Effect of chlorpyrifos on survival and virulence of native entomopathogenic nematode

Combining compatible insecticides with entomopathogenic nematodes may constitute an effective alternative to conventional chemical control as efficient tool for pest and disease control in areca nut and coconut. Hence, in vitro a compatibility test was conducted to evaluate the effect of chlorpyrifos which is widely used against root grubs on native entomopathogenic nematode isolate, Steinernema carpocapsae (CPCRI-SC1). Results indicated that different concentrations of chorpyrifos significantly influenced the infective juveniles (IJs) mortality at 96 h of exposure. The maximum percent mortality of infective juveniles was recorded at higher concentration of insecticide 3200 ppm (31.5%) followed by 1600ppm (26.2%), whereas minimum percent mortality (18.2%) was recorded at lower concentration (200 ppm) followed by 400 ppm (21.3%) at 96 h of exposure. Increase in the mortality of IJs was noticed with increase in concentration (200–3200 ppm) along with their exposure periods (24–96 h). No significant difference was recorded in mass production and infectivity of IJs exposed to different concentrations of insecticide on third instar G. mellonella. The results showed tolerance between native EPN isolate S. carpocapsae and chlorpyrifos insecticide at lower concentration as it does not affect the biological parameters of the native EPN isolate.