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为明确苏云金杆菌(Bt)与灭幼脲混剂对美国白蛾幼虫的毒杀效果,笔者对美国白蛾4龄幼虫围食膜被破坏的状况进行了研究。经超薄切片透射电镜观察发现,美国白蛾4龄幼虫围食膜表面平整光滑,有较明显的多层结构。经Bt+灭幼脲混剂对美国白蛾4龄幼虫处理120 h后,围食膜上出现较多的白色和黑色斑点状孔洞,并扩大为斑块状孔洞,形成了薄而易脆、易断或溃烂、无弹性的围食膜碎片,并致围食膜被破坏和幼虫死亡。试验证明,Bt+灭幼脲混剂对白蛾4龄幼虫围食膜的破坏最快,Bt和灭幼脲单剂次之。同时,经Bt+灭幼脲混剂及其单剂对美国白蛾4龄幼虫的林间LT_(50)、LT_(100)值和飞防毒杀速率测定发现,Bt+灭幼脲混剂对美国白蛾幼虫的致死率均高于其单剂,毒杀速率快于单剂。因此,Bt+灭幼脲混剂处理可较快地破坏白蛾4龄幼虫围食膜,其毒杀速率明显提高。
In order to clarify the poisoning effect of Bt and omlubi on the white lady moth larvae, the author studied the destruction of the peritrophic membrane of the 4th instar larvae of Coccinella septempunctata. By ultra-thin section transmission electron microscope observation, the 4th instar larvae of American white moth peritrophic surface smooth and flat, there are more obvious multi-layer structure. After treatment of 4th instar larvae of C. medinalis by Bt + MBU for 120 h, more white and black spots appeared on the peritrophic membrane and expanded to plaque-like holes, forming a thin and easy to crisp, easy Broken or ulcerated, inelastic peri-membrane fragments, and caused by the destruction of the peritoneal membrane and larval death. Experiments show that, Bt + MBF mixture on the 4th instar larvae of the white moth destruction of the peritoneal membrane fastest, Bt and chlorbenzuron single dose. At the same time, the LT_ (50), LT_ (100) values and the anti-toxin-killing rate of the fourth instar larvae of Bt + MB were observed. The results showed that Bt + Mortality of moth larvae were higher than a single dose, poisoning faster than a single dose. Therefore, Bt + MBF treatment can quickly destroy the 4th instar larvae of the white moth peritrophic membrane, the poisoning rate was significantly increased.