苏云金杆菌预处理棉铃虫二龄幼虫对氰戊菊酯抗性缓解及机理研究(英文)

本文研究了Ｂ．ｔ预处理棉铃虫二龄幼虫对氰戊菊酯抗性缓解及其机理。结果表明，Ｂ．ｔ预处理后的幼虫对氰戊菊酯的敏感性提高。与敏感性种群相比较，在Ｂ．ｔ预处理和未处理两个抗性种群的幼虫对氰戊菊酯的ＬＤ_５０之间纯比值分别大约增加了６２．６％和８０．９％。特异性酶抑制剂对乙酰胆碱酯酶的抑制作用显示，在活体内，马拉氧磷和甲基对氧磷对乙酰胆碱酯酶抑制效率提高了６６．１％和９９．８％；在活体外抑制效率（Ｉ_５０） ６０％和６７．５％及５５．６５％和８６．４％。同时，乙酰胆碱酯酶动力学各因子变化显著。在Ｂ．ｔ预处理的抗性棉铃虫幼虫中，Ｋｍ值从４５．５８％减少到６８．６２％；Ｋｉ值分别增加了２１．２％和４０．９％及３８．２％和６１．５％。这些结果证实Ｂ．ｔ预处理２４ｈ抗性棉铃虫二龄幼虫对氰戊菊酯的敏感性提高，乙酸胆碱酯酶的变化是重要原因之一。这一研究为在ＩＰＭ系统中将微生物杀虫剂和化学杀虫剂协调使用缓解棉铃虫对拟除虫菊酯类杀虫剂的抗性提供理论基础。

RESISTANCE ALLEVIATION IN THE LARVAL COT-TON BOLLWORM TO FENVALERATE AFTER PRE-TREATMENT WITH BACILLUS THURINGIENSIS

Resistance alleviation and mechanism in the 2nd instar larvae of one susceptible and two resis- tant strains of the cotton bollworm, Helicoverpa armigera to fenvalerate were studied at 24 h after the lar- vae were treated with Bacillus thuringiensis Berliner (B. t. ) preparation. The results showed that re- spouses of larvae with B. t pretreatment to fenvalerate were much more sensitive than those without B. t pretreatment. Compared with the susceptible strain (YZ-S), net ratios between LD_50s with and without B. t pretreatment in the two resistant strains increased approximate 62.6% and 80. 9%, respectivelyl inhi- bition of specific inhibitors to esterases displayed that efficacy of malaoxon and paraoxon methyl to acetyl- cholinesterase increased from 66. 1 % to 99. 8% in vitro and in vivo ; dynamic factors of acetylcholinesterase were significantly changed, in which K_m and V_(max) values decreased from 45. 58% to 68. 62% and Ki values of malaoxon and paraoxon methyl to acethylcholinesterase increased approaimate 60%. It suggested that the sensitivity of the 2nd instar larvae of resistant H. armigera to fenvalerate might increase after B. t pre- treatment for 24 h, and change of acetylcholinesterase was an important factor during resistance alleviation by B. t pretreatment. The research showed that it is practicable to bring the coordinated use of B. t and chemical insecticides in IPM system.