为了明确玫烟色棒束孢对小菜蛾的致病作用,分别以1×105孢子/mL和1×108孢子/mL浓度的玫烟色棒束孢菌株EBCL03011孢子悬浮液感染小菜蛾幼虫,观察了感病幼虫体表和体内器官组织的病变情况。结果显示,感病虫体颜色由局部浅褐色逐渐变为大面积深褐色,病虫出现缩短、强直等外部形态的变化。组织切片观察显示,接种后4 h,附着于体壁的分生孢子开始萌发入侵;16h后,小菜蛾内表皮被分解,菌丝段进入血腔。与此同时,被幼虫取食进入消化道的分生孢子也增殖产生菌丝段,以菌丝段突破肠壁细胞,向附近的脂肪体入侵;随着玫烟色棒束孢继续在虫体内增殖,24 h后各组织器官遭到不同程度破坏;48 h后,感病幼虫死亡,虫尸体内的菌丝突破体表,在虫体外形成菌丝层。表明玫烟色棒束孢入侵小菜蛾有两条途径,第1条为体表途径,第2条为消化道途径。 In order to elucidate the pathogenicity of C. obliquus to Plutella xylostella, the Plutella xylostella larvae were inoculated with spores suspension of M. gossypii at a concentration of 1 × 105 spores / mL and 1 × 108 spores / mL, respectively. The susceptible larvae surface and body organ tissue lesions. The results showed that the color of susceptible pests gradually changed from local light brown to large area dark brown, the emergence of diseases and pests shortened, and the changes of external morphology such as rigidity. Tissue sections showed that conidia attached to the body wall began to germinate and invading at 4 h after inoculation. After 16 h, the inner epidermis of Plutella xylostella was broken down and mycelium segment entered the blood cavity. At the same time, the conidia fed by the larvae into the digestive tract also proliferated mycelium segments, the mycelium segment broke through the intestinal wall cells and invaded the nearby fat body. With the continuous growth of C. obliquus, After 24 h, all tissues and organs were destroyed to varying degrees. After 48 h, the susceptible larvae died, and the mycelium in the dead body broke through the body surface and formed mycelium layer outside the insect body. The results showed that there were two pathways of invasion of Plutella xylostella into Plutella xylostella, the first one was the body surface and the second was the digestive tract.