棉红铃虫表皮结构与自然耐药性研究

THE CUTICLE STRUCTURE OF PECTINOPHRA GOSSYPIOLLA (SAUNSERS) AND ITS NATURAL TOLERANCE TO INSECTICIDES

棉红铃虫４龄漫行期滞育幼虫中后胸背板表皮高度皱缩，由外向内呈明暗相间的抛物线型片层结构；非滞育幼虫表皮不皱缩，呈明暗相间的直线型片层结构。漫行期滞育幼虫雌雄个体表皮厚度无明显差异，分别为２７．８９μ和２３．７５μ，是非滞育型幼虫对应性别的３．０１倍和２．８８倍。而表皮的致密程度在不同虫态和性别之间均无明显差异。说明表皮增厚引起的穿透速率降低是漫行期滞育幼虫耐药性高于非滞育幼虫的原因之一。

Electron microscopy scanning of the thorax sections of the pink bollworm showed that the cuticle of diapausing larvae at wandering stage was composed of many shade alternating with light parabolalike lamella and was highly wrinkly, and that of non-diapausing 4th instar larvae comprised many shade alternating with light line-like lamella without any wrinkles. The cuticle thickness had only slightly difference (<1.15-fold) between the female and male diapausing larvae at wandering stage, and were 3.01 and 2.88 fold, compared with those of the corresponding sexes of non-diapausing 4th instar larvae, respectively. The lamella per μ cuticle, regardless of physiological state (diapausing or non-diapausing) and sex, were very similar. The results suggested that one of the causes for the natural insecticide tolerance of diapausing larvae at wandering stage was the increase of cuticle thickness, and the sexual difference in natural insecticide tolerance was not obviously related to the cuticle structure.