二化螟Cry1Ac敏感和耐受品系的适合度差异及中肠蛋白酶活性比较

Comparison of fitness and midgut proteinase activities of Cry1Ac-tolerant and- susceptible Chilo suppressalis( Lepidoptera: Crambidae)

抗性/耐受种群的适合度代价和中肠蛋白酶活性研究是了解昆虫抗性进化、抗性产生的生理生化基础及抗性治理的重要内容。本研究以室内继代汰选的具有相同遗传背景的Cry1Ac耐受和敏感品系为研究对象,系统研究了两品系的适合度和中肠蛋白酶活性差异。研究结果表明,与敏感品系相比,耐受品系幼虫的存活率显著下降,且耐受种群不同日龄幼虫体重均低于敏感种群,20日龄时达显著差异;但两品系不同虫态的发育速度、蛹重、化蛹率、羽化率和成虫繁殖力均没有显著差异。中肠蛋白酶活性研究表明,耐受种群的类胰蛋白酶活性显著低于敏感种群,但两种群的总蛋白酶和类胰凝乳蛋白酶活性没有显著差异。该研究对于识别蛋白酶介导的Bt抗性机制和昆虫Bt抗性治理均具有重要意义。

Researches on fitness cost and midgut proteinase activities of resistance / tolerant strain are important bases to understand resistance evolution,resistance mechanism and resistance management.Midgut proteinase activities and fitness were compared between Cry1Ac-tolerant and-susceptible strains of Chilo suppressalis with the same genetic background. Larval survival rate of Cry1Ac-tolerant strain significantly decreased,compared to susceptible strain. Moreover,larval weights of different ages tolerant C. suppressalis obviously declined,and differed significantly at 20 d age,when compared with that of susceptible strain. However,there were no significant differences in developmental rate,pupal weight,pupation rate,emergence rate and adult fecundity of the two strains. Trypsin-like protease activities of Cry1Ac-tolerant C. suppressalis were significantly lower than those of susceptible C. suppressalis,but no significant differences were shown in total midgut protease and chymotrypsin-like protease activities of the two strains. This study is very meaningful to identify protease-mediated resistant mechanism and manage insect Bt-resistance.