甘薯麦蛾(鳞翅目:麦蛾科)幼虫及其被寄生幼虫田间分布图式的测定

Investigation on Spatial Patterns of Larvae of Brachmia trianuella (Gelechiidae: Lepidoptera) on Sweetpotato

本文就田间调查9组资料,应用Iwao的方法,分别对甘薯麦蛾(Brachmia triannuella)幼虫的空间分布图式以及被寄生幼虫和被寄生后幸存幼虫空间分布图式进行测定.结果表明:(1)甘薯麦蛾幼虫在薯田呈聚集图式.其分布的基本成分是个体群,个体群的分布是随机的,个体群内的分布也是随机的;个体群较致密,且大小约相等,个体群的平均面积约为0.56—1.12m^2.(2)被寄生幼虫的分布图式呈聚集型,说明甘薯麦蛾幼虫寄生蜂趋群集寄生.(3)被寄生后幸存幼虫的分布图式和原来的幼虫图式一样,都是聚集型,即Neyman A型,虽然有些田块幼虫被寄生率高达37.62％,但是寄生蜂的作用还未足以使寄主空间分布图式改变.

Nine data are tested by using the method of Iwao in study of spatial patterns of larvae of sweetpotato leaf folder (Brachmia triannuella) in sweetpotato fields. The test shows that the distribution of the larvae is of an aggregated pattern, namely, Neyman's series. The larvae occur as close colonies (mean size=0.56 to 1.11 square meter). Distribution of the colonies is random and intra-colony distribution is random too. Based on the pattern of population distribution the parasitism of the larvae are also discussed. Distribution of parasitized larvae is represented by aggregated pattern and distribution of the survival larvae is not changed, similar to original pattern.