变温条件下小菜蛾对不同温度效应杀虫剂敏感性的变化

Susceptibility variation of Plutella xylostella to insecticides with different temperature effects under variable temperature condition

为了明确变温环境条件对小菜蛾药剂敏感性的影响,本研究采用食料浸渍法比较了环境温度变化下四氯虫酰胺(正温度效应杀虫剂)和溴虫腈(无温度效应杀虫剂)处理对小菜蛾药剂敏感性的影响;模拟田间变温条件,研究这两种杀虫剂不同施药时间对小菜蛾毒力的影响。结果表明,四氯虫酰胺施药前,15、25、35℃预处理24 h,其35℃下温度系数分别为+28.53、+25.84和+18.77,均表现为显著的正温度效应,但温度系数随预处理温度上升而降低。溴虫腈在15℃预处理24 h,对小菜蛾表现为弱正温度效应,25℃和35℃下预处理均无温度效应。表明药剂处理前温度变化会影响杀虫剂的温度效应。在模拟田间变温的情况下,四氯虫酰胺经过高温预适应后于16:00(30℃)对小菜蛾的毒力最高(0.41 mg/L),显著高于清晨6:00(22℃)持续低温时的毒力(32.33 mg/L),毒力差异倍数高达78.85倍。一天中无温度效应杀虫剂溴虫腈的毒力受温度变化的影响较小。本研究为利用杀虫剂的温度效应指导田间高效防治小菜蛾提供了依据。

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.