玫烟色拟青霉对菜青虫的侵染及致病作用

采用扫描电镜和组织切片方法研究了玫烟色拟青霉(Paecilomyces fumosoroseus)对3龄菜青虫的侵染和致病作用。结果表明:玫烟色拟青霉可通过体壁侵染虫体。3龄菜青虫在接菌8h后,附着在虫体表面的孢子开始萌发,24h后菌丝即可穿透体壁进入血腔,48h后可见虫体内有部分菌丝体。侵入虫体内的菌丝对寄主组织没有选择性。菌丝首先在入侵的血腔中生长,然后侵入邻近的脂肪体和肌肉,随菌丝在虫体内的增殖,中肠、丝腺等相继被侵染。受侵的各组织器官均发生明显的病变,如体壁分离、脂肪体变形、溶解,肌纤维排列松散,中肠上皮细胞脱落并出现许多空泡等。

Histopathological changes of the larvae of Pieris rapae infected by Paecilomyces fumosoroseus

A histopathological study on the larvae of Pieris rapae(L)infected by Paecilomyces fumosoroseus showed that the fungi mainly infected the insect body by penetrating the cuticle.The conidia on the cuticle of the larvae of P.rapae germinated 8 hours after inoculation.The hyphae penetrated the cuticle of the 3rd instar larvae in 24 hours and some hyphae were observed inside the body in 48 hours.Invasion of the hyphae in the host tissues showed no significant selection.They grew in hemolymphs at the beginning and then entered the fat body and muscle.As the hyphae grew,the midgut and the silk gland were successively infected.Pathological changes occurred in all infected tissues and organs,including disintegrated cuticle,malformation and dissolution of the fat body,loose muscle fibre layout,disappearance of the midgut epithelial cells and vacuolization.