粟瘿蜂在板栗林的分布及抽样技术

对板栗Castanea mollissima林的系统调查结果表明栗瘿蜂Dryocosmus kuriphilus虫口密度随板栗林龄的递增而逐渐上升.间种了农作物的板栗林的栗瘿蜂虫口密度较低.在任何虫口密度下,栗瘿蜂在林间均为聚集分布,分布的基本成分是个体群,其聚集度随着种群密度的升高而增大.栗瘿蜂虫口密度在单株树树冠的东南西北4个方向之间无显著差异,而在内外层或上下层之间存在极显著差异.双对角线、单对角线、平行线和简单随机抽样方法均可作为栗瘿蜂虫口数量的调查方法.采用Iwao方法求出了最适抽样数和列出了序贯抽样表.

The spatial distribution of chestnut gall wasp and its sampling techniques in the chestnut plantation

The chestnut (Castanea mollissima) plantation was surveyed systematically. The results showed that the population density of chestnut gall wasp (Dryocomus kuriphilus) increased while chestnut trees grew from 1 to 6 years gradually. Compared with no intercropping treatment, the chestnut plantation intercropped with earthnut, corn and soybean had the lowest gall rate by the chestnut gall wasp.The distribution of chestnut gall wasp was the aggregated distribution patten and its basic component was individual colony in a chestnut plantation.The higher the population density of chestnut gall wasp ,the higher its aggregated degree in the chestnut plantation was.In the same crown level,the population density of chestnut gall wasp was not different significantly in the orientation of eastern,southern,western and northern branches of the trees. The population density was significantly different between inner and outer or upper and lower crown layers. The sampling methods,including intersecting diagonal,diagonal,parallel and random sampling were suitable to study chestnut gall wasp. The optimum sampling number and sequential sampling table were obstained by Iwao's method.