印楝素对水稻二化螟的生物活性及控制作用

 系统地研究了印楝素对水稻二化螟的生物活性及作用方式。试验结果表明，印楝素乳油对二化螟有胃毒、拒食、忌避、内吸等多种作用方式。0.75和0.50 mg/L印楝素乳油处理茭白饲喂3龄幼虫，幼虫分别于3、6 d内全部死亡；0.375、0.300和0.250 mg/L印楝素乳油低剂量处理茭白饲喂3龄幼虫，幼虫拒食率分别达94.38%、88.74%、80.07%；成虫产卵量分别下降80.70%、62.05%、40.86%。6、3和2 mg/L印楝素乳油处理初孵蚁螟，24 h内死亡率达100%。印楝素乳油对成虫产卵有显著的忌避作用。稻田喷施0.3%印楝素乳油62.5和125 mL/667 m2防治二化螟，21 d保苗效果分别为88.14%和94.13%，防治效果分别为85.36%和90.76%。表明印楝素对二化螟有较高的生物活性和理想的控制效果。

Control Effects and Biological Activity of Azadirachtin on Rice Stem Borer,Chilo suppressalis in Paddy Fields

Biological activity and functional pattern of aza di rachtin on rice stem borer, Chilo suppressalis were systemati cally studied. Azadirachtin had many functional patterns against Chilo s uppressalis as stomach poison,antifeedant,deterrence,sucking toxicity. After feeding on water-oats treated with 0.75 and 0.50 mg/L of azadirachtin, the 3rd-instar larvae were completely died in 3 and 6 days, respectivel y. The antifeedant rates of the larvae reached 93.48%,88.74%,80.07%, and the num ber of eggs laid were decreased by 80.70%,62.05%,40.86% after the 3rd-instar l arvae fed on water-oats treated with 0.375, 0.300 and 0.250 mg/L of azadirac htin, respectively. Mortality of the newly-hatched Chilo suppressalis reached 100% within 24 hours after treatment with 6,3 and 2 mg/L o f azadirachtin. Azadirachtin deterred adults from laying eggs on rice plants a fter application. The effects of saving seedlings reached 88.14% and 94.13%, th e control effects reached 85.36% and 90.76% at 21 days after spraying 0.3% azadi rachtin emulsion 62.5 mL/667 m 2 and 125 mL/667 m 2 in the paddy fiel ds, respectively. It was suggested that azadirachtin had higher biological a ctivity and efficacy against Chilo suppressalis in paddy fields .