印楝素乳油对斜纹夜蛾的生物活性及田间防效研究

在室内测定了印楝素乳油对斜纹夜蛾(Spodoptera litura)的生物活性，并进行了田间防治试验.结果表明，印楝素乳油对斜纹夜蛾具有多种生物活性，主要表现在对幼虫的拒食作用、生长发育的抑制作用和一定的毒杀活性，以及对成虫产卵的忌避作用.经印楝素处理后，幼虫平均发育历期延长、幼虫体重、蛹重、化蛹率和蛹羽化率显著低于对照，印楝素乳油12 μl·L^-1浓度处理3龄幼虫5和7 d后的体重分别是对照组的36.8%和14.5%，而幼虫平均发育历期比对照组延长6 d左右，化蛹率和蛹羽化率分别是27.79%和37.23%，显著低于对照组85.66%和82.11%.印楝素对低龄幼虫有一定的毒杀活性，而对高龄幼虫活性则很低.田间防治试验表明，印楝素乳油对斜纹夜蛾种群有良好的控制作用，施药7 d后其防治效果要优于化学农药10%除尽悬浮剂.

Bioactivity of azadirachtin and its field efficiency against Spodoptera litura

In this paper, the effects of varying concentration azadirachtin on tobacco cutworm Spodoptera litura were investigated in both laboratory and field. The results showed that azadirachtin exhibited a wide range of bioactivities, including anti-feeding, growth inhibition, larval toxicity, and oviposition deterrent. This compound could significantly reduce pupal weight and pupation and eclosion rates. After treated with 12 microl x L(-1) azadirachtin for 5 and 7 days, the third instar larvae only weighted 36.8% and 14.5% of the untreated ones, and their development took approximately 6 days longer, with a 27.79% pupation rate and a 37.23% emergence rate, significantly lower than the control by 85.66% and 82.11%, respectively. Azadirachtin was more efficient for the low instar larva than the old ones. Field experiments confirmed that after 7 days application, azadirachtin could effectively control Spodoptera litura, being more efficient than the chemistry pesticide, 10% Chu-Jin SC.