中文摘要：

研究了蜡蚧轮枝菌两个菌株No. V3.4504和No. V3.4505感染沙里院褐球蚧的外观症状、入侵体壁的过程及胞外蛋白酶与几丁质酶的作用. 结果发现，用菌株No. V3.4504的孢子悬浮液感染蚧虫2 d后，在虫体表面蜡粉稀薄的位置和柔软的虫体腹面出现了菌丝，5 d后菌丝覆盖虫体，7 d后菌丝层加厚，虫体开始死亡. 显微切片观察，在体壁的外表皮、内表皮和真皮层都发现了菌丝，说明该菌已侵染成功. 以蚧虫的表皮为培养基对这两个菌株连续培养8 d，发现菌株No. V3.4504的蛋白酶活性在前6天连续上升，最大值为（33.94 ± 1.61） U/g，然后降低；几丁质酶活性在前期维持在一个较低水平，d 5开始增加，最大值为（7.28 ±1.36） U/g. 菌株No. V3.4505的蛋白酶和几丁质酶的活性变化趋势与No. V3.4504相似. 说明蛋白酶在菌丝侵染体壁的前期发挥了作用，降解表皮中的蛋白质，使几丁质暴露，诱导几丁质酶的大量产生，从而分解几丁质. 图3 表2 参22

英文摘要：

Two strains No. V3.4504 and No. V3.4505 of the entomopathologenic fungus, Verticillium lecanii （Zimm.） were studied on the appearance of their infection to the scale insect, Rhodococcus sariuoni Borchsenius, and the process of inbreak and the role of their extracellular protease and chitinase. The results showed that after 2 days the scale insect was infected with spore suspension of the strain No. V3.4504, a few of hyphae appeared first on some parts of body surface with thinner wax powder. On d 5, hyphae almost covered the whole body of the scale. Up to d 7, hyphae layer became thicker and the scale insect was dying. Meanwhile, on the micrograph of integument of the scale, hyphae were found in exocuticle, endocuticle and epidermis. It means that this entomopathologenic fungus had infected the insect successfully. The two strains of V. lecanii were cultivated for 8 d continuously on the culture medium prepared with cuticle material of the scale insect. It was found the protease activity of the strain No. V3.4504 increased continuously in the first 6 days and gave a maximum value （33.94 ±1.61） U/g, and then decreased. Meanwhile, its chitinase activity maintained at a lower level at the earlier stage, then began to rise from d 5, at last the maximum value reached （7.28 ±1.36） U/g. A similar changing trend was found in the protease and chitinase activities in the strain No. V3.4505. It indicated that, the protease of the fungus played an important role in the early phase to decompose protein in the cuticle and made chitin exposure during V. lecanii infected the scale insect. With the decomposing of protease, the chitinase was induced plentifully and chitin in the cuticle was subsequently decomposed. Fig 3, Tab 2, Ref 22