烟草甲虫高毒力苏云金杆菌的分离与筛选

对云南7个优质主产烟区收集的450份烤后烟样,运用4%NaCl培养基选择分离法,分离出苏云金芽孢杆菌475株。其中对含毒蛋白基因cryⅠ及cryⅤ的18个Bt菌株用2龄烟草甲虫进行生物毒力测定,试验9 d后,9个Bt菌株生物毒力测定校正死亡率均超过80%;试验12 d后,5个Bt菌株生物毒力测定校正死亡率均超过95%。同时对分离出的Bt菌进行PCR毒素蛋白基因鉴定,含cryⅠ毒素蛋白基因的Bt菌有7株,出菌率为1.47%;含cryⅤ毒素蛋白基因的Bt菌11株,出菌率为2.32%;没有含cryⅢ毒素蛋白基因的Bt菌。因此,为进一步用苏云金芽孢杆菌防治烟叶仓贮害虫提供了科学依据。

Isolation and Selection of High Toxicity Bacillus thuringiensis to Lasioderma serricorne

475 Bacillus thuringiensis strains were isolated from 450 tobacco sample collected from 7 main tobacco-produced area in Yunnan by the method of 4% NaCl cutural medium and identification of them were done by means of PCR toxin gene.The results indicated that 7 Bt strains which plating efficiency was 1.47% contained cryⅠ toxin gene,11 Bt strains contained cryⅤ gene which plating efficiency was 2.32%,there was no Bt isolates containing cryⅢ gene.The bioassay toxicity of 18 Bt isolates containing cryⅠand cryⅤ gene was determinated to Lasioderma serricorne(F.)second instar,the results showed that there existed all of 9 Bt with over 80% corrected mortality 9 days after inoculation and 12 days after that 5 isolates with over 95% corrected mortality.From these the conclusion can be drawn that Bt is potential by used to control pest on stored tobacco leaf.