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模拟自然界中云斑天牛Batocera horsfieldi(Hope)成虫的生活状态,建立室内人工饲养及生测方法,对苏云金芽胞杆菌(Bt)的杀虫活性进行测定。将苏云金芽胞杆菌菌悬剂涂抹在野蔷薇枝条表面,饲喂云斑天牛成虫,20 d后统计死亡率、体质量变化及产卵数量。在室内测定了80株苏云金芽胞杆菌的活性,通过1次初筛和2次复筛,筛选到1株对云斑天牛成虫有较高致死率的菌株ZQ-51。该菌株处理云斑天牛成虫后平均死亡率为53.33%,平均体质量减少率和平均产卵减少率分别是5.67%和12.48%,与对照差异均极显著。从感染死亡的成虫肠道中重新分离了该菌株,并验证分离的菌株与ZQ-51具有相似的形态特征和杀虫活性,表明苏云金芽胞杆菌可通过云斑天牛取食进入肠道而发挥杀虫作用。
To simulate the living conditions of Batocera horsfieldi (Hope) adult in nature, indoor artificial feeding and bioassay methods were established to determine the insecticidal activity of B. thuringiensis (Bt). Bacillus thuringiensis suspension was smeared on the surface of wild rosebush and fed on the adults of Phalaenopsis glaucoma. After 20 days, the statistical mortality rate, the change of body weight and the number of spawning eggs were measured. The activity of 80 Bacillus thuringiensis strains was determined in the laboratory. One strain of ZQ-51, which has a high lethality to adults of Yunpeisi, was screened through primary and secondary re-screening. The average mortality rate of the strain was 53.33% after treatment of the adults and 5.67% and 12.48% of the average reduction rate of body weight and average spawning rate, respectively. The difference was significant compared with the control. The strain was re-isolated from the intestine of the infected adult and the isolated strains were confirmed to have similar morphological characteristics and insecticidal activity as ZQ-51, indicating that Bacillus thuringiensis can kill Bacillus thuringiensis by feeding into the intestine and killing Insect effect.