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.