Population dynamics of Bactrocera dorsalis Hendel at different habitats in relation to meteorological factors

Abstract: 【Objective】The oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae) is one of the major and widespread destructive pests in agriculture with a host range of > 46 families and 250 species of fruits and vegetables in temperate, tropical and sub-tropical areas. Adult oriental fruit fly lay eggs inside the fruits of different types of host plants for feeding and oviposition, costing millions of dollars every year. This pest represents a major biosecurity threat to the horticulture sector of many countries in the world. The objective of this study is to determine the population dynamics of B. dorsalis in evergreen citrus and deciduous persimmon orchards in Guangxi, and analyze the correlation between population dynamics of B. dorsalis and meteorological factors. Information gained from this study is expected to provide effective strategies for managing this pest.【Methods】Sex pheromone traps were used to detect the population dynamics of B. dorsalis in the citrus (Guangxi Academy of Specialty Crops, Guilin City) and the persimmon orchards (Pingle and Gongcheng Counties, Guilin City) in Guangxi from 2015 to 2017. Two traps (distance of each trap = 30 m) were hung on fruit trees within these areas mentioned above. The sex pheromone traps were set at 1.5-2.0 m above the ground (modified by the species of fruit tree) and were checked once every 10 days. Numbers of male B. dorsalis captured by these traps were recorded. Meteorological data including ten-day mean maximum temperature (℃, X1) , mean minimum temperature (℃, X2) and mean temperature (℃, X3) ; ten-day rainfall amounts (mm, X4) ; and ten-day sunlight hours (h, X5) were provided by Guangxi Meteorological Administration.The correlation between population dynamics of B. dorsalis and these meteorological data, and the principal components in these main meteorological factors were analyzed using SPSS software.【Results】Males of B. dorsalis were captured by sex pheromone traps from late May to middle Dec. in the seasons from 2015 to 2017. Periods of inception of peak, peak of emergence, and end of peak of B. dorsalis in the citrus orchard were consistent with those in persimmon orchards, which occurred in late May, late May to Nov. and middle Dec., respectively. A few male adults were captured by sex pheromone traps in Jan. and Feb. from 2015 to 2017, which were the coldest months during the year. Higher number of male adults captured by sex pheromone traps in Jan. and Feb. indicated greater likelihood of population outbreak in this year. Population dynamics of B. dorsalis had positive correlations with the ten-day mean maximum temperature, mean minimum temperature and mean temperature, and ten-day sunlight hours in both citrus and persimmon orchards from 2015 to 2017 (p < 0.05) . However, ten-day rainfall amounts had not any correlation with the population dynamics of B. dorsalis in the two different habitats (p > 0.05) . Ten-day mean maximum temperature and ten-day mean minimum temperature were the important meteorological factors influencing the population dynamics of B. dorsalis in the citrus and persimmon orchards. In the citrus orchard in Guilin, the proportions of variance contribution of ten-day mean maximum temperature and ten-day mean minimum temperature were 89.190% and 10.139%, with function expressions of F1 = 0.000 X1 + 0.005 X2 + 0.129 X3-7.855 X4-42.622 X5 and F2 = 0.000 X1 +0.004 X2 + 0.138 X3 + 6.629 X4-48.457 X5, respectively. In the persimmon orchard at Pingle County, proportions of ten-day mean maximum temperature and ten-day mean minimum temperature were70.433% and 27.201%, with function expressions of F1 = 0.001 X1 + 0.004 X2 + 0.093 X3 + 4.787 X4-32.231 X5 and F2 = 0.001 X1 + 0.003 X2 + 0.104 X3-3.964 X4-38.480 X5, respectively. In the persimmon orchard at Gongcheng County, proportions of ten-day mean maximum temperature and ten-day mean minimum temperature were 78.929% and 19.436%, with function expressions of F1 = 0.000 X1 + 0.005 X2 +0.099 X3-6.026 X4-32.602 X5 and F2 = 0.000 X1 + 0.004 X2 + 0.106 X3 + 5.024 X4-39.649 X5, respectively.【Conclusion】Population dynamics of B. dorsalis in evergreen citrus orchards was similar to those in deciduous persimmon orchards in Guilin, Guangxi Province. Higher number of male adults captured by sex pheromone traps in Jan. and Feb. means higher possibility of the population outbreak in this year.Ten-day mean maximum temperature and ten-day mean minimum temperature were the most important meteorological factors influencing the population dynamics of B. dorsalis in Guilin, Guangxi Province.