| The biology including duration,life history,host,super cooling point and freezing point of Bactrocera dorsalis (Hendel) (Diptera:Tephritidae) was studied. The result indicated that the duration of eggs,larvae,pupae and adults is 1.7 days,8 days,13 days and 60 days under 25±1℃. B. dorsalis has 6-7 generations each year in Shanghai landscape green spaces and overwinters in the pupal stage. The super cooling point of larvae,pupae and adults is -5℃,-9℃and -12℃, and the freezing point is -2℃.-7℃,-7℃.There are 7 main host plants of Bactrocera dorsalis (Hendel) (Diptera:Tephritidae) in Shanghai urban green space investigated:Amygdalus persioa L., Ziziphus jujube Mill., Citrus L., Pyrus L., Citrus medica L., Chaenomeles Lindl., and Punica granatum L.. The preference order is:Citrus L.>Amygdalus persioa L.>Ziziphus jujube Mill.>Pyrus L.> Citrus medica L.>Chaenomeles Lindl.>Punica granatum L. B. dorsalis prefers the fruits. Three to four plant species among the 7 host plants simultaneously exist in the same one urban green space. Therefore, the adults of B. dorsalis may inter-transfer among the different host plants according to the fruits. Further more, they develop a mechanism of transfer and harm.In order to identify the factors affecting the population dynamics of the oriental fruit fly, B. dorsalis, in Shanghai landscape green spaces, we inspected the population level with the entrapment method of adult fruit fly, including 7 influencing factors, such as host plant species, quantity, the distance between living places of population and food facilities, garbage stations, fruit markets, average air temperature and average relative humidity per day. The results indicated that the correlation coefficient between the population level and the host plant quantity was 0.938. Therefore, the host plant quantity is the most important factor affecting the population level of the oriental fruit fly. The correlation coefficient between the population level and the distance between living places of population fruit markets is -0.996, which is with the negative correlation. The cluster analysis demonstrated that the population level and the distance between living places of population and garbage stations was classified into one class, and they were grouped into one class with the distance between living places of population fruit markets, so these indicated that the population level was related to the distance between living places of population and garbage stations, fruit markets.To study the effects of Co60-y ray on Beauveria bassiana, the Co60-y ray is used to pupa of B. bassiana. Treatment time is 31 min and the rate is 3.08Gy/min with total dosage of 95.5Gy. The results indicated that the treated female and the treated male can not propagate, the treated female and the untreated male can not propagate, and the untreated female and the treated male can not propagate, but the untreated female and the untreated male propagate normally.The results indicated that all pupa treated with Co60-y is sterile.Twelve strains of Beauveria bassiana (Bb1824, Bb1840, Bb1853, Bb1981, Bb1995, Bb2003, Bb268, Bb853, Bb886, Bb1035, Bb1205, Bb2264) were seleted to posses the virulence to dipterous insect. Through the observation of the colony morphological characteristics, mensurate the sporulation and conidia germination, six strains (Bb886,Bb1035,Bb1824,Bb1981,Bb2003, Bb1840) were dominant than others, including mycelium grows fast, higher sporogenous ability and higher conidia germination ratio. By the method of bioassay, the strain of Bb886 was filtered from 6 strains, which has highest infection ratio, mortality and lowest LT50 to B. dorsalis larvae, the Infection ratio is 86.7%, corrected mortality is 89.2% and LT50 is 5.18 days under the 2×107/mL conidia condition. |
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