关键词: 嗜线虫致病杆菌, 毒素, 棉铃虫, 中肠, 组织病理学

Abstract: Xenorhabdus nematophila HB310 is highly virulent to many insects, and it is symbiotic with Steinernema carpocapsae HB310. ToxinⅡwas obtained by salting out and native-PAGE from the cells of X. nematophila HB310. The histopathology of toxinⅡto Helicoverpa armigera larvae was studied by dissecting and olefin slice of the midgut. The symptoms showed that the histopathology of the H. armigera midgut was similar to that of other novel midgut-active toxins such as the δ-endotoxins from Bacillus thuringiensis, as well as Tca from Photorhabdus luminescens W14. The midgut tissues of H. armigera fouth-instar larvae began to change after taken the toxinⅡorally in 6 hours. The foreport of peritrophic membrane began fracture and the cells extended. The epithelium was decomposed gradually and the midgut tissues were loose or disordered at last. The peritrophic membrane disappeared after 12 hours but appeared again after 72 hours following transient or sublethal exposure to the toxin. The toxinⅡalso directly destroyed the excised peritrophic membrane of H. armigera.

Key words: Xenorhabdus nematophila, Toxin, Helicoverpa armigera, Midgut, Histopathology