Study On Microstructure Of The Compound Eye And Phototactic Behavior Of Chrysopa Pallens Ramber (Neuroptera: Chrysopidae)

The microstructure of the compound eye under light and dark adaptation and phototactic behavior of the dominant predatory enemies Chrysopa pallens Ramber in many farmlands and orchards was investigated by means of optics microscope, histology and behaviour measure. The main results were as follows:1 The compound eyes with a shape of half sphere, located on the lateral upside of its head, was composed of 3 600 ommatidia in both sexes. The angle between the foremost and the hindmost ommatidia along the axis was 180°, and it was about 200°between the uppermost and the lowermost one. The exterior of compound eyes was smooth, the surface of ommatidium was hexagon, arranged closely just like beehive. The results showed that the compound eyes of Chrysopa pallens had square-built eyeshot, and high sensitivity.2 The organization of the compound eye of C. pallens belonged to the type of superposition eye with a clear zone. Each ommatidium contained corneal lens, crystalline cone, 6 to 8 retinula cells and basement membrane where the pigment granules could be observed, which were encompassed by two primary iris pigment cells and six secondary iris pigment cells in periphery. The microstructure of compound eye of C. pallens was so different in dark or light adaptation. In dark adaptation, the crystalline cone opened obviously and the 5～7 distal retinula cell nucleus moved close to the crystalline cone, the pigment granules of secondary iris pigment cells surrounded the crystalline cone, the distance of the longitudinal movement of pigment granules on basement membrane among the rhabdoms was about 19μm. In light adaptation, the crystalline cone closed or opened slightly, both the distal retinula cell nucleus and the most of pigment granules of secondary iris pigment cells moved to proximal end and surrounded retinula cells column, and the distance of the longitudinal movement of pigment granules on basement membrane among the rhabdoms was about 45μm. No differences in the microstructure of compound eye were observed between male and female under the same light- or dark-adaptation respectively.3 In a certain range of white light intensity (Log4.5～Log0.0), after two hours dark-adapted, The intensity influence the phototactic behaviour response, the stronger the luminance, the higher the phototactic behaviour rate. The change of the prophase is not evidence, but the anaphase is the current of quick, when the light intensity was biggest(Log0.0), the phototactic behaviour rate reached biggest, so the whole curve appeared a near "J" shape; compared with phototactic behaviour, it was stochastic of photophobism response, showing no orderliness, the max. was 4.5%. It was coincident in the behavior to white light between male and female.The innovation of this study is that, we found that the ommatidium of C. pallens was characterized by the crystalline cone closing or opening, the longitudinal movement of distal retinula cell nucleus and pigment granules on basement membrane, excepted the longitudinal movement of secondary iris pigment granules.