Characteristics of trehalase and inhibitory effect of seven insecticides on its activity in plutella xylostella

Author of the article:MA Jun WANG Han ZHOU Xiao-mao

Author's Workplace：Institute of Pesticide Science, Hunan Agricultural University

Key Words： Plutella xylostella (L.); trehalase; characteristics; insecticides

Abstract：The characteristics of trehalase in Plutella xylostella (Linnaeus) and inhibitory effect of four insecticides on trehalase activity of the 4th instar larvas were studied. The results obtained from experiments in vitro indicated that the optimum pH value of trehalas was 6.0, and the optimum temperature was 50℃. The Michaelis constant (Km) of trehalase hydrolyzing trehalose was (12.57±0.99)mmol/L. The maximum velocities (Vmax) hydrolyzing trehalose was (0.775±0.04)mmol/(min •g pro). At the 40mg/L of insecticides (profenofos, methomyl, fenobucarb and spinosad), there are different inhibitory effects on trehalase in 4th instar larvas of Plutella xylostella, their percentages of inhibition to trehalase activity were 25.83%, 20.19%, 18.99% and 18.62% respectively. Their inhibitory effects on trehalase activity were enhanced with the increasing of insecticide concentrations.