苏云金杆菌对菜青虫的毒力测定及田间防治效果

本文报导1974—1980年间利用苏云金杆菌(Bacillus thuringiensis)的几个变种对菜青虫(Pieris rapae L.)的毒力测定和田间防治试验结果。室内菌效试验结果指出,不同菌剂的1×10~8/ml孢子、晶体混合液处理后2天可获90％以上死亡率,某些菌剂的1×10~7/ml悬液2天内可获55—100％死亡率。室内毒力测定结果看出,HD-1和B-Hm-18对3龄幼虫毒力随菌剂浓度递减相应减低,致死中浓度(LC_(50))随作用时间增长而降低。田间防治实践所用浓度不宜过低。对菜青虫的毒力直线回归的斜率b值经多次测定范围为0.44—2.65。田间防治试验结果表明,1×10~8/ml的菌液浓度一般可使虫口减退90％以上,以B-Hm-18效果较好。0.1×10~8/ml菌液的防治效果与80％敌敌畏1:800药液防治效果相同,0.4×10~8/ml菌液防治效果显著高于敌敌畏。同浓度的HD-1(美国高效菌种)和B-Hm-18(我院分离菌株)菌剂间防治效果无显著差异。结果指出利用苏云金杆菌可以在生产上有效地防治菜青虫。

THE EFFECTIVENESS OF BACILLUS THURINGIENSIS FOR THE CONTROL OF IMPORTED CABBAGEWORM(Pieris rapae L.)

The effect of several strains of Bacillus thuringiensis on the imported cabbageworm (Pieris rapae L.) was studied in laboratory and field experiments in Harbin region between 1974—1980.The results of laboratory tests showed that a concentration of 1×10~8/ml of spores-crystals mixture of some preparations gave 89.5—94.7％ larval kill, and a concentraiion of 1×10~7/ml of other preparations gave 55—100％ larval kill respectively 2 days after application.Dosage mortality curves and LC_(50) values of HD-1 and B-Hm-18 were calculated for laboratory tests by probit analysis. The results indicated that LC_(50) value decrcased with increasing action time, and the slopes of the mortality regression lines were 0.44—2.65.In field experiments, preparations of several strains of Bacillus thuringiensis used at the rate of 1×10~8/ml obtained more than 90% pest population reduction. HD-1 and B-Hm-18 used at the rate of 0.4×10~8/ml afforded better control than DDVP.These results suggest that the Bacillus thuringiensis could be used successfully for the biological control of P. rapae in Harbin region.