研究了作用机制完全不同的苯甲酰基脲类(氟铃脲)和双苯甲酰基肼类(抑食肼和虫酰肼)昆虫生长调节剂(IGR)及其混用对棉铃虫的生物活性和作用方式。供试3龄幼虫经氟铃脲点滴处理后，逐渐表现活动缓慢、反应迟钝、取食减少，最终死亡。死亡幼虫体壁薄而易破，头部背面呈现明显突起的白色透明水泡状(易破体并有体液流出)，部分虫体黑化，表现明显的蜕皮障碍。3龄幼虫经抑食肼处理后，最先也表现为行为迟缓、食量减小，最终死亡的幼虫虫体缩小并发黑，部分存活的幼虫2 d后即蜕皮。氟铃脲与抑食肼混合处理后，部分试虫呈现氟铃脲的中毒症状，部分试虫则表现抑食肼中毒症状，少量个体两种症状并发。氟铃脲对棉铃虫3幼虫的LD50值(点滴法)和1龄幼虫的LC50值(叶片法)分别为0．7434μg a．i．／头和2．0592 mg／L，表现出很强的触杀作用和胃毒作用；虫酰肼对棉铃虫1龄幼虫也具有较强的胃毒作用，LC50值为25．2576mg/L；抑食肼对棉铃3龄幼虫触杀毒力很弱，LD50值超过39．3633μg a．i．／头。氟铃脲与虫酰肼混合处理后，对棉铃虫的作用以相互独立作用为主，但氟铃脲1 mg／L加虫酰肼5mg／L则呈现增效作用。%Symptom,toxicity and mode of action of insect growth regulators (IGRs), hexaflumuron,tebufenozide and RH5849, to cotton bollworm, Helicoverpa armigera (Hubner) were observed and assessed. After treated topically by hexaflumuron,the 3-instar larvae tend to move slowly with little sensitivity to a stimulate,fed on litter food an eventually die with the thin integument and a white transparent prominence on head. Some dead larvae become black and show failure of molt. The 3-instar larvae treated by RH5349 are also inactive in moving and feeding,dead larvae are in black and shrunken bodies,and living larvae abnormally molt in advance. After treated by the mixture of two chemicals, some larvae show the poisoning symptom of hexaflumuron, others are the symptom of RH5849, whereas a few larvae show mixed symptom. Hexaflumuron has a high contact toxicity to cotton bollworm, with 0.7434 μg a.i./larva of LD50 in topical application test, and a high stomach toxicity with 2.0592 mg/L of LC50 in leaf dipping bioassay. Tebufenozide is also stomach poisoning with 25.2576 mg/L of LD50, but RH5849 has little contact poison with more than 39.3633μg a. i./larva of LC50. In the mixture with different ratios , hexaflumuron and tebufenzide are independent in action to the bollworm except the ratio of hex aflumuron 1 mg/L and tebufenozid 5 mg/L that tends to be synergistic.
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