【摘要】 东北农业大学昆虫教研室从黑龙江地区病死鳞翅目昆虫体内分离出苏云金杆菌（Bacillusthuringiensis,Bt）菌株74株，随后以甘蓝夜蛾为供试昆虫对这些菌株的毒力进行了测定，结果表明，很多菌株对甘蓝夜蛾的初孵幼虫均具有一定的毒力，经过初筛、复筛，试验选出了毒力相对较高的5个菌株，当菌液浓度在8×10~7个芽孢·mL(－1)时,甘蓝夜饿死亡率分别达到80％～95％，Lc50分别为43，63，68，710，1778倍液。更多还原

【Abstract】 74 Bacillus thuringiensis (Bt) strains were isolated from corpses of Lepidopterous insects. The strains were used to conduct bioassay compared with their toxicties on cabbage armyworm Mamestra brasica(L.). The results showed that M. brassicae larvae were sensitive to many of the strains. Five Bt strains of high toxicity were also screened according to the bioassay. The mortality of M. brassicae larvae treated with the 5 strains at concemration of 8×107 spores. mL-1 was 80% ~ 95%. The Lc50 of the 5 strains to M. brassicae larvae were 43, 63, 68, 710and 1778 respectively.更多还原