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机构地区:[1]浙江省上虞市林业站,浙江上虞312300 [2]浙江省林科所,杭州311300
出 处:《昆虫天敌》1999年第2期65-69,共5页Natural Enemies of Insects
摘 要:根据10个样地100株粟树8452茶果枝剪枝标实象(CyllorhynchitesursulusRoelofs)为害状调查数据,分析为害状的空间分布格局。结果显示:东、南、西、北四个方向为害程度差异不显著。树枝顶部为害程度显著低于下部各个方向,达1.05倍。样地间差异也达到极显著水平,而且这种差异与样地的管理水平相一致。该种群为害状空间分布的基本成份为个体群,总体为聚集分布。用Iwao回归法分析,得出理论最适抽样数(n)回归式为:n=(1.67/X+0.07)/D2,式中X为粟枝平均被害率,D为允许误差。在防治指标定为果枝被害率10%时,序贯抽样的累积被害率上下限(T’(0))为:T’(0)=10×9.54×。每平方米土壤虫口密度和树上虫口密度相关性式为:Y=3.9883×P-0.3016,相关系数为0.95。式中Y为P分别为剪枝粟实象树上成虫密度与土壤中幼虫密度。这说明可用土壤中幼虫密度估计成虫密度。By the data collected from the field invetigation the space pattern of symptom caused byweevil (Cyllorhynchites ursulus Roelofs) on its host plant ( Castanea mollissima Bl. ) branches wasanalyzed in this paper. The differenes of the damage symptom among the branches in different di-rections was significant . The damage on the top portion of host plant canopy was much lowr thanthe other directions. The differece among different sampled fields was also significant.This differ-ence was coinidence with the management levels. The spece pattern belonged to the aggregatedtype. By lwao regression model the formulae of optimum sample units (n)was:n=(1.67/x +0.07)/D2 where X was the mean of the damage rate of plant branches, D was relative errors. Whenthe control index was 10% of the branches damaged, the upper or lower limits functions of accumu-lated damage rate (T(0) ) to judge whether the insecticides were used or not were: T(o) = 10 × n9.54 ×n , where n was the number of sample units. lts adult lived on the tree canopy, its larvaelived in the soil under tree canopy . By the densities of the adult and the larvae the relationship be-tween them was analyzed with the ther regression model . The model was Y = 3.9883 × P-0.3016,where Y was the adul density, P was the larvae density. The regression coefficient was 0. 95. Thisindicated by the be density in soil the adult density could been estimated.
分 类 号:S436.64[农业科学—农业昆虫与害虫防治] S4[农业科学—植物保护]
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