白僵菌不同菌株对美国白蛾幼虫的致病力及田间应用研究

Pathogenicity and field application of different strains of Beauveria bassiana on larvae of Hyphantria curea Drury

为了研究白僵菌不同菌株对美国白蛾的生物防治效果,选用11株不同寄主来源的球孢白僵菌菌株,研究其在室内对美国白蛾1龄幼虫的致病力,筛选出高效致病菌株后,进一步测定其毒力,并且在田间条件下测定高效致病菌株对美国白蛾幼虫的防治效果.结果表明,4个白僵菌菌株Bb10331、Bb7725、Bb7716和Bb87303对美国白蛾有较强的毒力,120 h后的校正死亡率均超过90%,其中Bb7725的防治效果最好.4个菌株孢子的致死中浓度（LC50）为3.28×106~6.42×106m L-1,半数致死时间（LT50）为71.13~94.39 h.田间实验结果表明,孢子浓度为1×108 m L-1的白僵菌在施药7 d后防除效果较好,为74.40%~87.29%.

To evaluate the biocontrol effect of different strains of Beauveria bassiana on Hyphantria curea Drury,the pathogenicity of eleven strains of B. bassiana from different hosts was conducted on the first larvae of H. curea. Furthermore,the highly pathogenic strains were screened and the toxicity was measured. The results showed that：there were four strains of B. bassiana（Bb10331,Bb7725,Bb7716 and Bb87303）with highly infecting effecet. The corrected mortality was more than90% after infection for 120 h,and the strain of Bb7725 had the best effect among the four strains. Meanwhile,the LC50 of the four effective strains was 3.28 ×106-6.42 ×106spores m L-1and the LT50 was 71.13-94.39 h. The field trials showed that the controlling effect of the four strains of B. bassiana at the concentration of 1 ×108spores m L-1reached the highest values of74.40%-87.29% after spray for 7 d.