对甜菜夜蛾高毒力苏云金杆菌的分离及生物测定

从山野和田间土壤样品中分离得到苏云金杆菌62株.经镜检发现,这些菌株的伴孢晶体多数呈菱形(79.0%).初步的生物测定结果表明,62株菌株中对小菜蛾、斜纹夜蛾和甜菜夜蛾的致死率超过90%以上的菌株分别有44株、8株和6株.其中CAB109、CAB110、CAB116和CAB162这4株菌株对上述3种害虫都表现出高活性.将其稀释成1.0×107cfu/mL后进一步生物测定的结果,CAB109菌株对甜菜夜蛾的毒性最高,死亡率达100%,比已经商品化的NT0423农药高15%.血清型鉴定发现,CAB109菌株的血清型为H7,属aizawai亚种,而其余3种血清型全部为H3abc,属kurstaki亚种.对害虫的毒性和血清型都表明,CAB109菌株是防治甜菜夜蛾非常有潜力的优良菌株.

Isolated and bioassay of Bacillus thuringiensis with high insecticidal activity to spodoptera exigua

62 Bacillus thuringiensis isolates were collected from wild and field soil samples.By microscopic examination found that these crystal of mostly isolates were bipyramidal shape（79.0%）.The preliminary bioassay results showed that during the 62 isolates the preliminary of 44 isolates on Plutell xylostella were more than 90%,and the same affection between 8 isolates on Spodoptera litura and 6 isolates on Spodoptera exigua.Bioassay results were four isolates（CAB109,CAB110,CAB116 and CAB162） had high activity controlling for P.xylostella,S.litura and S.exigua.Than thinning these four isolates to 1.0×107cfu/ml for further bioassay that the highest toxicity with 100% mortality belong to CAB109 isolate which was 15% higher than NT0423 pesticide.Identification of serotype showed that CAB109 isolate was H7 belong to aizawai subspecies and other three were H3abc type to kurstaki subspecies.All the results showed that the best prevention of isolate was CAB109 for S.exigua.