烟粉虱成虫在西兰花菜地种群分布型及抽样技术

Spatial distribution pattern and sampling technique of Bemisia tabaci adults in the broccoli fields

通过对西兰花莲座期的烟粉虱不同发生密度地块调查,取得了21组样本资料,应用聚集度指标法、I-wao法和Taylor法等对其空间分布型进行测定检验,结果表明烟粉虱成虫在西兰花秧苗上呈聚集分布,其聚集度是随着种群密度升高而增加。其聚集原因经Blackith种群聚集均数测定,当m<3.7049时,其聚集是由于某些环境如气候、栽培条件、植株生育状况等等所引起的;当m≥3.7049时,其聚集是由害虫本身的聚集行为与环境条件综合影响所致。在此基础上,通过几种抽样方式比较测定,以五点式为最佳,并提出了最佳理论抽样数和最佳序贯抽样模型:N=1/D2[0.8751/m+0.6753],Tn=0.8751/[D02-0.6753/n]。

Three methods of aggregated indices, Iwao＇s way （regressive relation by M^＊-m） and power law of Taylor were used to determine the spatial dislribution pattern of B. tabaci adults in the broccoli field. The results showed the pattern of B. tabaci adults belonged to aggregation distribution, and aggregation indices increased with the increase of population densities. The cause of aggregation was tested by Blackith＇ s method, when rn 〈 3. 7049, the aggregation pattern was caused by some environmental factors such as climate, cultivation, plant growth and so on; When rn 〉13.7049, the aggregation causes were induced by behaviors of the insect and environmental conditions. Based on the distribution pattern, it was found that five points sampling was optimum among several sampling methods. The models for determining the optimum theoretical sampling number and the optimum sequential sampling are proposed. The models were as follows：N=1/D^2[0.8751/m＋0.6753],Tn=0.8751/[D0^2-0.6753/n].