多杀菌素对天敌昆虫白蛾周氏啮小蜂的毒力评估

Toxicity assessment of spinetoram against naturalenemy insect Chouioia cunea (Yang)

【目的】生物防治与化学防治相结合是害虫综合防治的重要策略,蛹寄生蜂白蛾周氏啮小蜂是一种重要的天敌昆虫,在美国白蛾的生物防控中起关键作用。本研究旨在评估农林生产中常用的广谱、低毒杀虫剂多杀菌素对白蛾周氏啮小蜂的安全性。【方法】采用药膜法检测多杀菌素对小蜂的毒力,并检测亚致死浓度多杀菌素处理后,小蜂体内解毒酶活性的变化。【结果】多杀菌素对小蜂无短期(1 h)触杀作用,但随施药时间延长,其对小蜂的毒杀作用增强,25 mg·L-1多杀菌素施药2 h后,可诱导约18.67%小蜂个体死亡。施药4 h后,不同浓度多杀菌素对小蜂的毒杀作用差异最明显,低浓度(5 mg·L-1)多杀菌素可诱导11.33%小蜂死亡,而中、高浓度多杀菌素(≥15 mg·L-1)可诱导77.33%~88.00%个体死亡。施药6 h后,LC 50值达7.44 mg·L-1,安全系数为0.31,属高风险性农药。此外,亚致死浓度多杀菌素可明显诱导小蜂羧酸酯酶活性提高,对乙酰胆碱酯酶与谷胱甘肽-S-转移酶活性具有剂量效应。【结论】多杀菌素对白蛾周氏啮小蜂的毒力作用较强,在美国白蛾生防区需慎用。

【Aim】The combination of biological and chemical controls serves as an important preventive strategy for pest control.Chouioia cunea,a pupa wasp,is a critical natural enemy insect and plays a key role in the biological control of Hyphantri acunea.The purpose of this study was to evaluate the safety of spinetoram,which was a broad-spectrum and low-toxic insecticide commonly used in agriculture and forestry production on C.cunea.【Method】The toxic film method was employed for detecting its toxicity to C.cunea.The detoxification enzyme activities of C.cunea were determined after the treatment of spinetoram with sublethal concentration.【Results】The results showed that spinetoram had no obvious killing effects on C.cunea in a short period of time like one hour.However,the application of 25 mg·L-1 spinetoram for 2 h caused a mortality rate of 18.67%,suggesting that the increased treatment time might be a deciding factor for more apparent toxicity.Low dosage(5 mg·L-1)induced 11.33%mortality while relatively high dosage(≥15 mg·L-1)could lead to 77.33%-88.00%mortality rate.Our data also revealed that the value of LC 50 reached 7.44 mg·L-1 with the safety factor being 0.31 after 6 h post stimulation,indicating that this pesticide could be regarded as high-risk cytotoxicity.Meanwhile,the treatment of spinetoram with sublethal concentration enabled the activities of detoxification enzymes to be significantly up-regulated as well as acetylcholinesterase and glutathione-S-transferase to be influenced in a dose-dependent manner.【Conclusion】The results showed that spinetoram has a strong toxic effect on C.cunea,and should be carefully considered in areas where H.cunea is used.