中文摘要：

为评价新近发现的润州黄色杆菌（Flavobacter runzhou）GXW15-4菌株对鳞翅目害虫的防治效果,以甜菜夜蛾不同龄期幼虫为靶标害虫,采用浸叶法进行了毒力测定。结果表明,该菌（浓度55.00×10^6cfu/ml）对甜菜夜蛾低龄幼虫有较强的致死率,1-4龄幼虫接种后第3d的累积死亡率分别为96.15%、80.00%、67.86%和67.86%;致死中浓度分别为3.93×10^6、6.34×10^68、.59×10^6和10.2×10^6cfu/ml。取食含有高浓度菌液的叶片后第4d,1龄幼虫全部死亡,2至4龄幼虫死亡率达90%左右。润州黄色杆菌对同龄期甜菜夜蛾幼虫的半致死时间随药液浓度的增大而缩短;在同一浓度下,幼虫的半致死时间随龄期增大而延长。

英文摘要：

The non-spore-forming bacterium, Flavobacter runzhou, is a recently found insect parthogen that infects numerous lepidoterous larvae. The virulence of the parthogen against larvae of the beet armyworm, Spodoptera exigua Hübner （Noctuidae, Lepidoptera） was evaluated by the leaf-dip method. The pathogen caused higher mortalities to young larvae than to old larvae, the cumulative mortality （5.50 × 10^7 conidia/ml） at three days after the initial infection was 96.15 % for the first instar, 80.00% for the second, 67.86% for the third, and 67.86% for the last instar larvae, respectively; and at four days after the initial infection, mortality of the first instar larvae was 100%, that of the 2nd to forth instar larvae was ca. 90%. The LD50 was 3.93 × 10^6 conidia/ml for the first instar, 6.34 × 10^6 conidia/ml for the seeond, 8.59 × 10^6 eonidia/ml for the third, and 1.02 × 10^7 eonidia/ml for the last instar larvae. The LT50 to the same instar larvae was shortened with inerease in eoneentration of the pathogen formulation,while it was extended with increase of larval instars at the same concentration of the pathogen formulation.