Study On Microstructure Of The Compound Eye And Phototactic And Colour Behavior Of Maladera Orientalis Motsch(Coleoptera: Scarabaeidae)

The external morphology and microstructure of the compound eye under light and dark adaptation and phototactic of the pests of apple-growing areas Maladera orientalis Motsch in orchards in Taihang Mountains were investigated by means of scanning electron microscope, histological and behaviour measure. The main results were as follows:1. The compound eyes with a shape of heart, located on the lateral upside of its head, was composed of 3 800 ommatidia in both sexes. It have a special structure of triangular cone connection with forehead on the upper side of antennae,some short hair on the surface. The surface of everyone ommatidium was irregular hexagon. A special concavo-convex structure formed by striae was situated in the middle of facets.There was no difference significantly on every regional.2. The organization of the compound eye of Maladera orientalis Motsch belonged to the type of superposition eye with a clear zone. Each ommatidium contained corneal lens, crystalline cone, retinula cells, rhabdom, basement membrane and tracheal system where the piglment granules could be observed. Dioptric apparatus were composed of corneal lens which was the flat on the outer margin and the salient in the center and infundibulate type of crystalline cone which can be divided. Retinula cell column beneath each crystalline cone were encompassed by 4-6 retinula cells gathering together in“flower petals”, with clear zone in the surrounding areas. Rhabdom was composed of the specilization of retinula cells. The area of cross section of the middle segment of rhabdom was largest. Rhabdom adjoining in basement membrane were distributed a mass of pigments. The microstructure of compound eye of M. orientalis was so different in dark or light adaptation. Photographic systems of M. orientalis was regulated by crystalline cone opened and closed or opened slightly, movement of the proximal retinula cell result in the change of clear zone, movement of pigments granules of basement membrane.3. The spectrum stimulus gave rise to the phototaxis of M. orientalis. The spectral sensitivity response at 14 monochromatic light selected through 340 nm to 605 nm occurred in curve with multiple peaks, the primary peak in 400 nm(violet) and 420 nm(blue-violet) was the highest response rate of phototaxis 39.72%, the secondary in 498 nm(skyblue)and 524 nm(green) was the highest response rate of phototaxis 38.6%,and the rest in 380 nm and 562 nm was 37 %; the phototaxis female adult higher than male adult significantly.4. The intensity of light stimulus gave rise to the phototaxis of M. orientalis. The response rate of phototaxis was increasing as the negative relative intensity of light, it was showed as curves with " " shape in white light and with upper and lower wave irregularity in 420nm.The phototaxis rate increased obviously with increased strength of light in Log2.5-0 in the white light, however, The phototaxis rate decreased obviously with increased strength of light in Log4.5-2.5 in the white light. The best of the phototaxis rate were located at Log3.0, 1.5, 0, Log4.5-4.0 second place.It was coincident in the behaviour to light between male and female.5. Study on taxis responses of M. orientalis for ten kinds of the different color with the green for the control group. The result showed that different coloured influenced capturing M. orientalis, Significantly more M. orientalis were caught in violet than others. It is not significant among violet, sky blue on capturing difference sex M. orientalis.The taxis responses rate of red was differences under the different background. The study showed that the dimming mechanism of the ommatidium of M. orientalis 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 of basement membrane.This innovation is confirmed both the spectrum and intensity of light stimulus gave rise to the phototaxis of M. orientalis, it seemed to play a more important role that the light intensity than spectrum,but the effect level was also involved with wavelengths.At the same time, confirmed the best taxis responses of M. orientalis was violet, sky blue of ten kinds of the color. These findings reveal the intrinsic link between the source of the characteristics of light and the provision of a scientific reference of phototaxis in M. orientalis or the beetles,but also provided a new thinking and approaches sustainable use to control pests of agriculture and forestry.