| The oriental fruit fly, Bactrocera dorsalis Hendel (Diptera, Tetriphitidate), has a strong reproductive and environmental resilience, once spread and colonization, can easily cause a serious impact on local agricultural production. To infer the population dynamics of oriental fruit fly in new area of invasion, the relationship with climate meteorological factors, the influence of temperature and host plants on the growth and development, and scientific prevention strategy were analysed. The results are as follows.1 Population dynamics of oriental fruit fly in Shapingba, and its relationship with climate factors.The population dynamics of oriental fruit fly was monitored year-round in Shapingba, Chongqing. The B. dorsalis occured seasonally only between May and November, with one yearly peak between August and October. The population in 2012 was large great and outbreaking, and was significantly different from other years. The climate factors including monthly mean temperature, humidity, rainfall were analyzed by principal component analysis and correlations analysis. The result showed that the rainfall and temperature are the main climate factors, the monthly mean temperature, monthly maximum temperature, monthly minimum temperature and rainfall were positively correlated with population dynamics (P<0.01). The sunlight hours, rain days and humidity were not positively correlated with population dynamics (P>0.05). Because of the largest correlation coefficient (R=0.718), the rainfall was the key factor which influence the population fluctuation of B. dorsalis. Combined with the data analysis, the rainy season in Shapingba is April to June and August to October, during which the B. doralis’ occurred early and its population was in peak. The rainfall of this period largely determines the occurrence of B. dorsalis all the year around.2 The effects of temperature on the development of B. dorsalis populationThe research measured developmental period, survival rate, developmental threshold temperature, sex ratio and other data of B. dorsalis’egg, larvae and pupae. At 14℃, the developmental period of B. dorsalis’egg, larvae and pupae was 7.14d, 38.46d and 41.48d, respectively. The developmental period of a generation was longest at 89.08d. At 34℃, the developmental period was shortest, which was 16.12d from egg to adult, and was 1.02d,7.45d and 7.68d for the egg, larvae and pupae stages, respectively. By using linear regression model, the developmental threshold temperature was 10.3℃,9.7℃ and 9.6℃ for the egg, larvae and pupae stages, respectively. The effective accumulation temperature was 398.2 day-degree for the developmental period from egg to adult, and was 27.1,185.2 and 188.7 day-degree for egg, larvae and pupae stages, respectively. The survival ratio of its each developmental stages was lower at low and high temperature. The survival ratio of larvae was higher than egg and pupae at the same temperature. Temperature had no significant effects on the sex ratio of B. dorsalis. The egg laying amount of B. dorsalis was less at low and high temperature than preference temperature.3 The effects of host plants on the development of B. dorsalisThe research measured the effects of several main fruits and vegetables in Shapingba on the development and oviposition preference of B. dorsalis. The results indicated that the egg laying amount on the several host plans was including ioquat, citrus, peach, tomato, peach, grapes, watermelon, pumpkin, zucchini, cucumber. The egg laying amount on loquat was most than others. In the experiment of survival and development, B. dorsalis could not complete the life cycle on pumpkin, tomato, zucchini, cucumber, which showed that the four kinds of vegetables were unfavorable for the B. dorsalis. The developmental period of B. dorsalis was shortest on Ioquat, which was 1.58d,10.58 and 10.12d for egg, larvae and pupae, respectively. The weight of pupae on peach was heaviest,14.21mg. There was no significant difference of the weight on citrus and pear. The lightest weight of pupae was 11.37mg on watermelon. Because of the fruiting period of the main host plants was consecutive, B. dorsalis could occur continuously all year round. |
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