Study On External Morphology And Microstructure Of The Compound Eye Of The Moth, Acleris Fimbriana Thun-berg

The external morphology and microstructure of the compound eye under light and dark adaptation of the pests of apple-growing areas Acleris fimbriana Thun-berg in Chinese northern orchard were investigated by means of scanning electron microscope (SEM) and histological method. The main results were as follows:1. The compound eyes with a shape of half sphere were convex. There were about 924 ommatidia in the eye of the female, and about 1,100 in that of the male. The hexagonal facts were more rules in most parts of the eye, with a diameter of ca 19μm in the male. A little of the facets were 5-sided and the sharp of the rim ommatidia was irregular and hexagon. The ommatidial surface was revealed to be covered evenly with corneal nipples. A special concavo-convex structure formed by striae was situated in the middle of facets. There were some sensilla between the ommatidia which near the center and dorsal eye region of the male and female. Compared with the eyes of the center eye region, sensilla of the dorsal region were more in number and longer in length.2. Each ommatidium contained corneal lens,crystalline cone, 5 retinula cells, rhabdom, basement membrane and tracheal system where the piglment granules could be observed, which were encompassed by six primary iris pigment cells and six secondary iris pigment cells in periphery. Its compound eyes capped by strongly convexly curved corneae of 20μm in diameter. Beneath each corneal lens a cluster of four cone cells enveloped by six primary pigment cells. The sensory apparatus adjoins the dioptric apparatus, with the rhabdom abutting on. The small clear-zone can be found between dioptric apparatus and retinula cell column.3. The microstructure of compound eye of A. fimbriana was so different in dark or light adaptation. In dark adaptation,the crystalline cone opened obviously and the five distal retinula cell nucleus moved close to the crystalline cone and the primary iris pigment cells nuclear moved close to the crystalline cone cells. The pigment granules of secondary iris pigment cells surrounded the crystalline cone. In light adaptation,the crystailine cone closed or opened slightly. The five distal retinula cell nucleus and the pigment granules distributed upper retinula cells column. The primary iris pigment cells nuclear moved to the distal crystalline cone. Filaments were showed between each retinula cell, the form of organization changed in different states. In light adaptation the sharp was linear and in dark adaptation was fibrillar. No differences in the microstructure of compound eye were observed between male and female under the same light- or dark- states respectively.The study showed that the dimming mechanism of the ommatidium of A. fimbriana was characterized by the crystalline cone closing or opening, the longitudinal movement of distal retinula cell nueleus and the primary iris pigment cells nuclear and pigment granules. Furthermore, filaments were showed between each retinula cell, the change of the form of organization were the first observation in different states.