复配杀虫剂BtA对棉铃虫的杀虫效果及对天敌中红侧沟茧蜂蛹和成虫的触杀毒性(英文)

为了科学施药， 合理保护和利用天敌对棉铃虫Helicoverpa armigera进行综合防治， 本研究在室内测定和比较了复配杀虫剂BtA和7种常用杀虫剂（阿维菌素、 Bt、 β-氯氰菊酯、辛硫磷、定虫隆、氰戊菊酯和丁硫克百威）对棉铃虫的杀虫效果及对其天敌中红侧沟茧蜂Microplitis mediator蛹和雌成虫的触杀毒性。采用浸叶法测定杀虫剂在室内72 h内对棉铃虫3龄幼虫的杀虫效果， 结果表明： 与其他杀虫剂相比， BtA对棉铃虫幼虫具有更高的毒性和致死效应 (LC₅₀=0.7364 mg/mL)。将棉铃虫3龄幼虫接到用浓度4 mg/mL上述杀虫剂分别处理过的大白菜上24， 48和72 h， 发现其死亡率之间存在显著差异（P≤0.05）。但在72 h后， BtA和其他杀虫剂对棉铃虫幼虫的杀虫效果之间并无显著差异(P>0.05)。BtA施药后， 随着时间的延长， 棉铃虫幼虫的死亡率也在增加。另外， 通过杀虫剂对寄生蜂中红侧沟茧蜂蛹和雌成虫的触杀毒性的生物测定发现： 与β-氯氰菊酯、 氰戊菊酯和丁硫克百威相比， BtA对中红侧沟茧蜂蛹和雌成虫的毒性较低， 对其蛹和雌成虫致死率分别仅为13.82%和7.33%。本研究证明BtA对鳞翅目害虫具有中等毒性， 而对寄生蜂中红侧沟茧蜂则具有较低毒性。

Bioefficacy of a mixed biocide BtA against Helicoverpa armigera (Lepidoptera: Noctuidae) and its contact toxicity to pupae and adults of parasitoid Microplitis mediator ( Hymenoptera: Braconidae)

To scientifically utilize biocides and conserve natural enemies for integrated control of Helicoverpa armigera, the bioefficacy of a mixed biocide BtA in comparison with seven commercial insecticides (abamectin, Bt toxin, beta-cypermethrin, phoxim, chlorfluazuron, fenvalerate and carbosulfan) against H. armigera and its contact toxicity to pupae and female adults of parasitoid Microplitis mediator were bioassayed in the laboratory and compared. Toxicity of these compounds on the 3rd instar larvae of H. armigera by leaf dip bioassays within 72 h in the laboratory showed that BtA had high toxicity (LC₅₀ = 0.7364 mg/mL) in comparison with the other commercial insecticides. Mortalities of the 3rd instar larvae of H. armigera exposed to Brassica rapa var. pekinensis treated with 4 mg/mL of these compounds were significantly different at 24, 48, and 72 h in pot trials (P≤0.05). BtA had no significantly different bioefficacy (P>0.05) in the experimental pots from the other commercial insecticides against H. armigera larvae at 72 h after treatment. After application of BtA, larval mortality of H. armigera increased as time extended. Bioassay of the contact toxicity of these compounds to pupae and female adults of parasitoid M. mediator showed that BtA has low toxicity to pupae and female adults of M. mediator, with the mortality values of 13.82% and 7.33%, respectively, in comparison with fenvalerate and carbosulfan. We so concluded that BtA has a moderate toxicity to the lepidopterous pest, H. armigera, and a relatively low toxicity to its parasitoid, M. mediator.