Sensitivity And Behavioral Reponse Mechanism Of Anomala Corpulenta Motschulsky To Light Signal

Phototaxis of insect is one of the most generally biological phenomena in nature.Research on insect behavioral and physiological mechanisms of response to light signal,which not only has important scientific significance, but also improve the control technologyof the harmful insects. Anomala corpulenta Motschulsky is one of the most importantunderground pest species in farmland, recently, as light traps as main control is an importantmeans of pest control. The exoskeleton of A. corpulenta can selective reflection left-handedcircularly polarized light, and which are greatly interest to many biologists. The light traps hasbroad-spectrum to trap the insect species, which is obviously harmful to protect insectbiodiversity in the farmland. In order to elucidate the mechanism of insect phototaxis andoptical signal in insect vision and use to improve pest control technology by light traps, thisthesis try to research on visual structure characteristics of A. corpulenta, light perceptionmechanism, electrophysiological behavioral response to light intensity, color vision andpolarized light visual, and biological significance of polarized light signal, the mainconclusions are as follows:1. The feature of compound eyes and the regulation mechanism of light werepreliminarily identified in A. corpulenta. According to the observation by electron microscopyand optical microscope, the thickness of compound eye corneal is over50μm and more thanthe majority insects (<10μm), which is suitable to move in the soil. The compound eyes of A.corpulenta belong to the type of superposition eye with a “clear-zone”, which is characterizedby the crystalline cone closing or opening, the migration of secondary iris and membranepigment granules upon light/dark adaptation, crystalline cone is4or2division, crystallinecone splitting line closed, the migration of basement membrane pigment particles fromproximal to distal, the migration of the secondary pigment granules into the clear-zone underlight adaptation, preventing light receiving in the daytime. On the contrary while the splittingline of crystalline cone cracked at night, screening pigment granules collectively cluster indistal inter ommatidial spaces around the cone, and basement membrane distribution ofpigment granules in the proximal, easy to accept the weak light.2. The sensitive region of compound eyes of A. corpulenta located in the ultraviolet (400nm), green (498-562nm) and blue (460nm) region. Circadian rhythms can affect the spectralsensitivity, spectral sensitivity was significantly larger at night than in daytime, no significant effect between genders. The compound eyes of A. corpulenta adapts quickly to changing lightconditions, The amplitude of ERG (Electroretinogram) in response to white-light stimulivaried with the light intensity: the stronger the luminance, the higher the ERG value. There isno significant difference between circularly polarized light, line polarized light andunpolarized light.3. The insect will have phototaxis reaction under the monochromatic wavelengths between340nm and610nm spectrum. Phototactic behavior response rates were higher in themonochromatic light UV region (405nm), blue (460nm) and green (505nm and570nm) inmale and female. Sexes can affect on the phototactic behaviour, but only in the size of peak. A.corpulenta also can produce a certain phototactic behavior reponse under left and rightcircularly polarized light, horizontal and vertical linear polarized light stimulation. Butphototactic reponse rate of circularly polarized and linear polarized light was significantlylower than unpolarized light, field trapping tests also showed that unpolarized lightsignificantly was higher than circularly polarized and linear polarized light in trapping effectof A. corpulenta. These results demonstrate that A. corpulenta is able to distinguish polarizedand unpolarized light.4. Visual loss was obvious significance on mating behavior in A. corpulenta. The abilityof polarized light reflection loss on exoskeleton of A. corpulenta, mating rate wassignificantly decreased. A. corpulenta does use the green circular polarization signal for matechoice in its visual environment.The research showed that A. corpulenta had no significant difference with mostterrestrial insects in light sensitivity and phototaxis under different wavelengths light. There isa huge problem to design specific light trap by wavelengths. It was proposed that current lighttraps should be used timely in the area of specific pests rampant occurrence period in singlecrop. A. corpulenta has polarized vision, and the study is the first to show left circularlypolarized light cuticular reflections from A. corpulenta is one of the biological significance,and A. corpulenta can communicate with conspecific species. These results will contribute tounderstand and develop insect vision ecology.