Dual role of esterases in insecticide resistance in the green rice leafhopper

摘要: Abstract The role of esterases as related to insecticide resistance was studied in an organophosphorus (OP)-resistant strain the green rice leafhopper. As judged by p -nitrophenyl acetate hydrolysis, 21, 5, and 74% esterase activity located nuclei/mitochondria, microsomes, soluble fraction, respectively. All fractions were active hydrolyzing malathion, paraoxon, fenvalerate. Hydrolysis malathion fenvalerate increased with time while that paraoxon reached a plateau within 15 min. Since considerable amount -nitrophenol detected reaction at 0°C zero time, formation may be due phosphorylation rather than phosphorotriesterase action. results suggest dual for mechanisms; catalyst hydrolysis fenvalerate, binding protein oxygen analogs other OP insecticides, both which would protect intrinsic target, acetylcholinesterase, from inhibition. Chromatofocusing fraction resolved five peaks, I–V. These toward three general substrates well insecticides tested, except Peak I overall too low. Thin-layer agar gel electrophoresis showed chromatofocusing peaks I–V corresponded electrophoretic bands E 1 –E 5 , some previously shown associated resistance. these explain cross-resistance between synergism carbamate insecticides.