刚果红对棉铃虫中肠围食膜的影响及其病毒增效作用

通过观察棉铃虫幼虫正常围食膜（peritrophic membrane, PM）的形态、结构和组成，研究了刚果红对棉铃虫幼虫围食膜的破坏作用及其对棉铃虫核多角体病毒（HaNPV）的增效作用。结果表明，棉铃虫的围食膜分布于整个中肠，包裹着食物呈液囊状，类似于Ⅰ型围食膜；健康的围食膜呈无色、透明网状结构，并具有一定韧性，经刚果红染色后呈现桔红色。使用不同浓度梯度的刚果红喂食5龄幼虫，结果显示摄取含1.5%和2.0%刚果红的饲料2.5 h后，宿主不能形成完整的围食膜，而是形成易脆无弹性的围食膜碎片。经过恢复实验后发现，刚果红对围食膜的破坏作用是瞬时的，可以在较短时间内得到修复。用1.0%刚果红喂食初孵幼虫，发现1.0%刚果红对棉铃虫的幼虫生长不能产生明显的影响。1.0％刚果红能加强棉铃虫幼虫对HaNPV的敏感性，缩短病毒杀虫时间，能使5龄幼虫的病毒感染致死率达到63％，对HaNPV具有非常显著的增效作用。

Effect of Congo red on peritrophic membrane of Helicoverpa armigera (Hübner) and its viral-enhancing activity

The morphology, structure and component of normal peritrophic membrane (PM) were observed, and the disruptive effect of Congo red (CR) on the PM of larvae and its viral-enhancing activity to HaNPV in Helicoverpa armigera were studied. The results indicated that the PM of H. armigera resembled typeⅠ, which spread nearly the whole midgut and presented as a vacuole. The normal PM was colorless, transparent and stretchy. The PM dyed by CR appeared as a bisque netlike structure. When the 5th instar larvae were reared on the diets with different concentrations of CR, the larvae synthesized fragile PM fragments instead of intact PM after consuming the artificial diets with 1.5% and 2.0% CR for 2.5 h. However, the resumptive experiments testified the disruptive effect could be restored by rearing the larvae on the diet without CR. Although 1.0% CR did not affect the growth of larvae, it could enhance the sensitivity of larvae to virus infection, shorten the killing time by virus, and cause the mortality of 5th instar larvae as high as 63%.