灭幼脲Ⅰ号对松毛虫作用方式的研究

THE WAY OF DIMILLIN EFFECT ON LARCH CATERPILLAR

用含有致死剂量的蜕皮抑制剂灭幼脲I号(Dimilin)饲料喂养落叶松毛虫幼虫,幼虫内部组织的中肠及马氏管未出现变化,体壁出现一些变化。显微切片观察,内表皮组织呈现损伤,不是完全附着在上表皮上,出现疏松分离状态。同时进一步对体壁定量化学分析表明,内表皮中的几丁质沉积量约减少了12％;而另一方面,蛋白质的含量不受影响。这就揭示了灭幼脲I号对松毛虫有一种特殊的作用方式——妨碍几丁质的沉积,使新形成的表皮缺少硬度,在蜕皮期间不能正常蜕掉旧皮最终导致死亡。从此证明灭幼脲T号和常规杀虫剂性质不同,能引起松毛虫在蜕皮期间死亡,如剂量较低,可使发育迟缓或畸形。

The larch caterpillar (dendrolimus superans) was reared on the forage which contained lethal dose of moulting inhibitor Dimilin. No abnormal changes were observed both in midgut and malpighian tubes under microscopic examination of paraffin sections of those tissues. But injury was found in integument the endocuticle did not adhere to the epicuticle thoroughly, and they appeared in a loosen separate state. Besides. the quantitative analysis of body wall has also showed that after the larvae were treated with Dimilin, the chitinous content in the endocuticle reduced by 12%, whereas protein content did not be affected. This indicates that Dimilin has a special way of action to hamper the rate of chitinous deposition at the endocuticle. So, the cuticle thus formed lacks hardness, it can not meet with pressure or can not give enough force tosupport the muscle during moulting. For this reason, the larvae can not moult off the old Cuticle and finally died. Experiments show that at all experimental concentrations of Dimilin, the effect of this insecticide is different from that of conventional pesticides. Even below the lethal dose, the tested larvae died during moulting. At lower dose, larvae appears being stunted in development or deformed. In this case, Dimilin is similar to anti-moulting hormones.