麦红吸浆虫越冬幼虫分布格局与抽样技术再研究

Distribution pattern and sampling technique of overwintering larvae of wheat blossom midge, Sitodiplosis mosellana (Diptera; Cecidomyoiidae)

采用研究昆虫种群空间分布格局的经典方法 ,通过对 3块地 6个样点各 1 0 0个样方连片逐一取样调查、频次分布拟合和 5种聚集指标分析表明 ,麦红吸浆虫越冬幼虫的田间分布格局为聚集分布 ,最适合奈曼分布型 ,其次适合负二项分布型。聚集强度因田块和样点而异 ;聚块面积为 1 0 cm× 1 0 cm或 1 0 cm× 2 0 cm,从而从理论上证明了目前小麦吸浆虫调查中所采用的 31 .85 πcm2× 2 0 cm或 1 0 cm× 1 0 cm× 2 0 cm取样单位是合理的。室内模拟“Z”字形、棋盘式、双对角线和平行线 4种抽样方法各 5、1 0、1 5个样方抽样结果比较表明 ,以双对角线 1

plots, each divided into 100 samples (a square of 10cm by 10 cm and depth of 20 cm per sample), were investigated in order to study the distribution pattern and sampling technique of overwintering larvae of wheat blossom midge, Sitodiplosis mosellana (Gehin) in 3 winter wheat fields. Data were analysed by the frequency distribution and 5 aggregation indexes respectively. Results showed that the Neyman's distribution model is most suitable. The next is the negative binormal distribution model. Aggregation degrees of larvae varied with various plots. Aggregation size is a square of 10 cm by 10 cm or a rectangle of 10 cm by 20 cm based on the Iwao's ρ indexes. Therefore, the sample size, used to investigate population density of the pest, with 31.85лcm 2 by 20cm (depth) or 10cm by 10 cm by 20 cm was proved to be feasible. Relative errors of 4 sampling methods including 'Z' shape, chess manual, twin diagonal line and parallel line with 5, 10, 15 samples, respectively, were compared each other through simulating samples indoor. The least error was found in the twin diagonal line with 15 samples.