新疆吐鲁番棉田海氏桨角蚜小蜂消长动态及空间分布型

Population Dynamics and Spatial Distribution of a Parasitoid Eretmocerus hayati in the Turpan Cotton Fields in Xinjiang

采用棋盘式取样调查吐鲁番棉田不同方位及棉株不同高度海氏桨角蚜小蜂(Eretmocerus hayati)的种群动态。调查结果显示,海氏桨角蚜小蜂对烟粉虱具有典型的跟随控制作用,各调查区海氏桨角蚜小蜂在下层与中层棉叶寄生率均显著高于上层(P<0.05),但下层与中层差异不显著(P>0.05),与烟粉虱自棉株下部逐渐向上危害的规律相吻合。海氏桨角蚜小蜂对烟粉虱若虫寄生率在棉田北区的西向显著高于南向(P<0.05),其他各区的方位间没有差异(P>0.05)。对海氏桨角蚜小蜂的多个聚集度指标和Iwao线性回归分析发现其空间分布型呈聚集分布,其聚集原因是由海氏桨角蚜小蜂行为和环境条件共同引起。应用Iwao的抽样模型建立了海氏桨角蚜小蜂的田间理论抽样公式:N=(4.2762/m+2.2534)/D^2。

Chessboard sampling method was adopted to investigate the population dynamics of Eretmocerus hayati on variant parts of cotton plants in different areas of the cotton field.Eretmocerus hayati showed a typical follow-up and control pattern towards Bemisia tabaci based on the investigation.The parasitic rate of Eretmocerus hayati at the middle part and lower part of cotton leaf were significantly higher than that at the high part in the investigation areas（P〈0.05）,which matches the lower-to-upper damage habit of the whitefly in the cotton field.Parasitism rate of Eretmocerus hayati to the whitefly on the west direction was significantly higher than the north direction in the northern area（P〈0.05）.No significant difference was found among directions of other areas.Aggregation indexes and Iwao linear regression analysis showed that Eretmocerus hayati presented aggregative spatial distribution in field conditions.This distribution pattern can be co-effected by the parasitoid＇s behavior and environment factors.Field sampling formula was built based on the Iwao sampling model：N =（4.2762/m ＋2.2534）/D^2.