Study On Infection Pattern And Envitonmrental Factors Affecting Colonization Of Metarhizium Pingshaense

China is known as the Bamboo Kingdom because of species and plantation area,and the species. The bamboo industry is one of the most important economic industriesin Zhejiang province. In recent years, due to changing of the cropping patterns, thedamage of the wireworm has increased year by year. The damage of bamboo wirewormshas caused huge economic loss, and the harm of the wireworm has become the bottl-eneck of development of bamboo industry in Zhejiang province. Wireworm is a soil-dwelling pest, and its control is very difficult. What’s more, many efficient pesticidesagainst wireworms were forbidden because of the high toxicity and residue in market,thusbiological control of wireworms became important significantly.. In present study,Metarhizium pingshaense which was isolated from dead wireworm of Melanotus cribric-ollis was studied. The infestation pattern of M. pingshaense on wireworms was observe-d by electron microscopy, and the techniques of solid-phase fermentation and the soilcolonization of this fungus were also studied. The results were as following:1. By scanning different areas of the wireworm infected by M. pingshaense, the re-sults showed that the spores were primarily on the sections between the conjunctiva ofthoracic leg and the end of leg. And on parts with thinner cuticle, such as inter segm-ental membrane of the abdomens and the pores, the spores were found as well. Where-as, few spores existed on the hard parts of body surface.2. The results of the elector microscope scanning of the wireworms infected withM. pingshaense showed that spores occurred signs of germination, and one side ofthem showed bud protrusions in12hours after inoculation, And after18hours, thebud protrusions increased further; After24hours, bud protrusions kept increase andless than length of spores, then the end were swelled and appressoriums formed; After30~36hours, germ tubes grew further and twice longer than the spore, budding tubesor appressorium body walls occurred on the wrinkles, and began to grow inside of thewireworms; After36~96hours, the mycelia invading wireworm body absorbed abunda-nt nutrients and propagated in large quantity, and then the body cavities were complete-ly filled, and finally the fungus broke through the epidermis and firstly grew whitemycelia on foot fossea; After120hours, the surface of bodies covered with white myc-eliaand green conidia.3. The results of the transmission electron microscopy observation of M. pingshaensinfecting wireworms showed that a few mycelium bodies aliened to the epidermis in 12-30hours after the inoculation; Due to the stimuli of adverse external environment,the section films extruded, the nuclear membranes thickened, and the chromatins conden-sed, which all enabled these wireworms to resist the external invasion;30hours afterthe infection, although a small amount of hyphas had invaded in the epidermis, the wir-eworm cells were still integral and the internal structures were relatively stable;64ho-urs later, the hyphal invaded in the fat bodies of the wireworms, and then the fat bodi-es were full of mycelium segment and spores;96hours later, the ribosomal began tofall,organelles were severely damaged, the ribosomal were completely off and finally th-e ce-ll organelles were completely vacuolated.4. We studied the factors affecting conidial production of wp08in the solid-phaseof process. The factors include the medium and their humidity, the inoculation, the inc-ubation time and the volume of medium in the culture flask. The results showed thatvermiculite and rice hull were fine carriers for the fungal culture. The mixture of cornand wheat bran were good food bases. The maximum conidial yield were all above2.7×10~9spores/g with different carrier. The best mixture ratio was1:2(rice: rice hull) andthe maximum conidial yield was58×10~9spores/g. Water content of the medium wasbest around70％when inoculation ratio was1:10(v/w)．The optimum time was14d andthe optimum volume of the medium was the half of the culture flask.5. The factors affecting the germination rate of M. pingshaense in different soilwere analyzed, and we found that the germination rate in black soil was highest, howe-ver the germination rate was not significantly different among4different soils. Atthetemperature of30°C the germination rate can reach at80%in black soil whenthe soil moisture is6%.At the temperature of20°C, humidity of6%or30°C, humid-ity of12%the germination rate can reach60%.Covered soil with kanamycin germina-tion rate is62.32%and non-covered soil with the adding of chloramphenicol the sporegermination rate reached52.12%, adding penicillin, rifampicin and streptomycin soilspore germination rate reached27.06%.The spore germination was inhibited by addingphoxim and fipronil and in non-covered soil the germination rate is0%. With the add-ing of pesticides, the spore germination rate is less than5%in covered soil.