荔枝园荔枝蒂蛀虫常规爆发期的种群空间分布格局

Spatial distribution patterns of Conopomorpha sinensis Bradley during its conventional population outbreak in litchi orchard

荔枝蒂蛀虫Conopomorpha sinensis Bradley是我国最重要的荔枝、龙眼蛀果类害虫之一。为了准确把握荔枝园中荔枝蒂蛀虫的分布规律,以便对该虫的危害盛期进行预测预报和采取防治措施,本文采用生物学统计方法和地理统计学方法对荔枝园中荔枝蒂蛀虫卵、蛹和成虫的空间分布特征进行了研究。结果显示:2019年5月和6月,无挂果荔枝树的有虫株率分别为67.74%和68.57%,而挂果荔枝树的有虫株率达90.91%和91.67%。该时期荔枝园内荔枝蒂蛀虫蛹的半变异函数最佳拟合模型均为球型模型,成虫均为指数模型,而卵在5月和6月的拟合模型分别为球型模型和指数模型。不同时期荔枝蒂蛀虫各虫态的拟合变异函数模型虽存在一定差异,但所指明的空间分布格局均为聚集分布。引起荔枝蒂蛀虫卵和蛹聚集分布主要由生境和自身生物学特性共同所致,但当虫口密度降低时,成虫的聚集分布仅由生境引起。另外,用Kriging插值方法生成的空间分布图显示荔枝蒂蛀虫卵、蛹和成虫均明显趋向于以挂果荔枝树为中心的聚集分布,聚集斑块由聚集中心区域向四周逐渐减小。5月至6月,荔枝蒂蛀虫卵、蛹和成虫在荔枝园内趋向以挂果荔枝树为中心的聚集分布,不同时期荔枝园内荔枝蒂蛀虫的聚集分布成因随种群密度变化有所不同。

Conopomorpha sinensis Bradley(Lepidoptera:Gracilariidae)is the most destructive borer pest of Litchi chinesis and Euphoria longan.The spatial distribution pattern of C.sinensis population were analyzed using biostatistical and geostatistical methods in litchi orchard for forecasting and scientific management of C.sinensis.The results showed that the ratio of infected trees was 67.74%and 68.57%for the fruitless litchi trees in May and June,and that was 90.91%and 91.67%for the fruiting litchi trees.The semivariogram curve models of egg,larva and adult of C.sinensis in May and June were as follow:The pupae were both spherical models.The adults were both exponential models.Therefore,it was found that the spatial distribution patterns of all the models were aggregated,although their models had a little different in different periods.The reason for the aggregation of C.sinensis egg and pupae were mainly its bionomics and environment,while the adult aggregation was only caused by the environment when its population density decreased to some extents.As the maps with Kriging interpolation described,the C.sinensis aggregation exhibited an obvious spatial aggregation centered on the fruiting litchi trees and the aggregated plaques decreased slightly from the aggregation center to edges during May to June.The egg,pupa and adult of the C.sinensis tended to an obvious spatial aggregation centered on the fruiting litchi trees.The reason for the aggregation of C.sinensis in the litchi orchard varied with its population density,but mostly caused by its bionomics or and environment.