Susceptibility variation of Plutella xylostella to insecticides with different temperature effects under variable temperature condition
In order to clarify the influence of variable temperature environments on the susceptibility of Plutella xylostella,we compared the effects of ambient temperature changes on toxicity of tetrachlorantraniliprole(positive temperature effect insecticide)and chlorfenapyr(no temperature effect insecticide)to P.xylostella using feed dipping method,and the effects of application time on the toxicity of two insecticides against diamondback moth under the condition of simulated field variable temperature.The results showed that the temperature coefficients at 35℃were+28.53,+25.84 and+18.77,respectively,after pretreatment at 15,25 and 35℃for 24 h before exposure to tetrachlorantraniliprole,which suggested significant positive temperature effects,while the temperature coefficients decreased with the increase of the pretreatment temperature.After pretreatment at 15℃for 24 h,chlorfenapyr showed a weak positive temperature effect on P.xylostella,but no temperature effect at 25℃and 35℃pretreatment.The results indicated that the temperature change before treatment would affect the temperature effect of insecticides.When simulated field temperature changes,tetrachlorantraniliprole showed the highest toxicity(0.41 mg/L)at 16:00(30℃)after high temperature preadaptation,which was 78.85 times significantly higher than that at 6:00(22℃)at continuous low temperature(32.33 mg/L).However,the toxicity of chlorfenapyr was less affected by temperature changes during the day.This study provided the basis for utilizing the temperature effect of insecticides to guide the efficient control of P.xylostella in field.
temperature coefficientPlutella xylostellainsecticidetoxicityvariable temperature
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