Influence of some Pesticides on Entomopathogenic Fungus Lecanicillium (=Verticillium) lecanii (Zimm.) ZARE & GAMS

An in vitro study was conducted to determine the interaction effect of ten pesticides tested at field recommended dose on conidial germination, vegetative growth and sporulation of Lecanicillium lecanii(ZIMM.) ZARE&GAMS. Compatibility of L. lecanii to different pesticides was found to be varied. Conidial germination was 99.3 and 85.7% in Pongamia oil and acephate, whereas, it was totally inhibited by the presence of chlorothalonil, iprodion + carbendazim, carbendazim and thiophanate methyl indicating that these pesticides were highly toxic. Dinocap recorded as moderately toxic while endosulfan, abamectin and ethion were least toxic based to the germination of conidia. So also Iprodion + carbendazim did not and carbendazim allow L. lecanii to put forth mycelium growth in their presence. Thiophanate methyl, Pongamia oil, acephate, endosulfan, ethion and chlorothalonil were observed to be innocuous pesticides registering growth of mycelium upto 2.33, 2.23, 2.23, 2.03, 2.03 and 2.00 cm dia., respectively, from 0.6 cm dia. held in the center of Petri plate on 14^th day after treatment. As far as sporulation is concerned, Pongamia oil alone recorded the maximum yield of 47.2x10⁶ conidia/ml followed by 18x10⁶ conidia/ml, in chlorothalonil as against 20x10⁶ conidia/ml in control, which means that the pongamia oil exhibited synergistic effect on L. lecanii, yielding more conidial spores. Thus, based on in vitro interaction study, pongamia oil alone was found to be safe to the entamopathogenic fungus L. lecanii in nature and iprodion + carbendazim and carbendazim were found to be highly toxic.