摘要
[Objective] This study was conducted to isolate and screen new Bacillus thuringiensis （Bt） strains against Lepidoptera insecticides. [Method] Bt strains were isolated from soil of Changbai Mountain area by temperature screening method, and highly-toxic Bt stains were then selected by biological determination and toxicity de- termination. [Result] From 150 soil samples, 18 Bt isolates were isolated, with an average isolation rate of 12.0%. Specifically, the isolation rate from mountain field was 8.5 %, and the isolation rate from farmland was 16.2%. The results of activity determination showed that there were17, 5 and 4 strains showing lethality rate over 90% against Plutel/a xylosrel/a, Spodoptera litura and Spodptera exigua, respectively, and among them, strain YNI-1 exhibited high activity against all the 3 kinds of in- sects. The results of toxicity determination showed that strain YNl-lhad the best fast-acting property against S.litura and S. exigua; strains with high toxicity against S. exigua were YN6-2〉YN1-1〉YN4-2〉YN2-6 sequentially; and toxicity of strains against S. /itura was in order of YN4-4〉YN1-1 〉YN6-1 〉YN4-1 〉YN2-1. [Conclusion] According to activity determination and toxicity determination, strain YN1-1 was screened as the target strain with wide spectrum, fast-acting property and high toxi- city.
[目的]分离筛选出对鳞翅目害虫高毒力的新苏云金杆菌。[方法]通过温度筛选法从长白山区土壤中分离出苏云金杆菌,再通过生物测定和毒力测定筛选出高毒力苏云金杆菌。[结果 ]从150份土壤样品中分离出18株苏云金杆菌,其分离率为12.0%,其中山地分离率为8.5%,农田分离率为16.2%。活性测定结果 ,18株菌株中对小菜蛾、斜纹夜蛾及甜菜夜蛾致死率超过90%的菌株分别有17株、5株和4株,其中YN1-1菌株对3种害虫都表现出高活性。毒力测定结果,YN1-1菌株对甜菜夜蛾和斜纹夜蛾的速效性最好;对甜菜夜蛾高毒力菌株依次为YN6-2>YN1-1>YN4-2>YN2-6;对斜纹夜蛾高毒力菌株依次为YN4-4>YN1-1>YN6-1>YN4-1>YN2-1。[结论]经活性测定和毒力测定,最终筛选出广谱性、速效性及高毒力的YN1-1为目标菌株。
基金
Supported by Natural Science Foundation of Yanbian University(2011-34)~~
