球孢白僵菌对斜纹夜蛾高毒菌株筛选与制剂的研发

Selection and Formulation of a Beauveria bassiana Strain with High Virulence towards Spodoptera litura(Lepidoptera:Noctuidae)

斜纹夜蛾Spodoptera litura是一种危害极大的农业害虫,为了探索1条可持续、无污染的新型防治方法,我们通过标准喷塔法从12株球孢白僵菌Beauveria bassiana中筛选出1株对斜纹夜蛾2龄幼虫高毒力的菌株———球孢白僵菌Bb2860菌株。在喷雾浓度为（2592±275）孢子.mm-2的高浓度下,菌株Bb2860对斜纹夜蛾2龄幼虫在第7d的校正死亡率达82.43%±6.03%。不同制剂的室内生测试验表明,孢子水悬液和2种油剂（分别为不含稳定剂和含有稳定剂）在中浓度319~529孢子.mm-2的喷雾浓度下,7d后对斜纹夜蛾2龄幼虫的累计死亡率分别为54.8%7、0.0%和76.7%;菌药协同作用为86.8%。另外,于2009年9月在安徽马鞍山进行自然条件下对花椰菜叶上斜纹夜蛾幼虫的田间小区药效试验。处理9d后,纯菌剂的相对防效为77.64%;低剂量和常规用量5%氟啶脲（抑太保）的相对防效分别为49.02%和89.70%;菌药混用的相对防效为91.13%。本研究显示出利用球孢白僵菌制剂及其与低剂量抑太保混用防治斜纹夜蛾的良好应用前景。

Spodoptera litura（Lepidoptera： Noctuidae） is a devastating insect pest on various vegetables,crops and economic plants.To explore alternative strategy for sustainable control of the pest population,12 strains of Beauveria bassiana were bioassayed under the concentrated standard spray of 2592（±275） conidia·mm-2.The strain Bb2860 was most virulent to the second-instar larvae of S.litura,causing a corrected mortality of 82.43%（±6.03%） at 7 d after spray.Subsequently,this strain was formulated with a mineral oil containing a stabilizer or not and bioassayed against the larvae.The fungal sprays of 319-529 conidia·mm-2 in water,oil formulation（with and without stabilizer） alone and together with 10% of the labeled application rate of chlorfluazuron resulted in the cumulative mortalities of 54.8%,70.0%,76.7% and 86.8%,respectively.The oil formulation with stabilizer was tested for field efficacy against the pest population on cauliflower in Maanshan city,Anhui Province during September 2009.Treatments with the oil formulation,10%（low dose） and 100%（standard control） of the labeled application rate of chlorfluazuron,and the combination of the fungal formulation and the low dose of chlorfluazuron resulted in the relative efficacies of 77.64%,49.02%,89.70% and 91.13% after 9 d,respectively.The results indicate that the combined spray of the oil formulation of B.bassiana and the low dose of chlorfluazuron were effective against S.litura.