小麦田草地贪夜蛾的发生为害、空间分布与抽样技术

Population occurrence, spatial distribution and sampling technique of fall armyworm Spodoptera frugiperda in wheat fields

草地贪夜蛾Spodoptera frugiperda(J.E.Smith)是中国重要的外来入侵害虫,我们调查了该虫在云南省寻甸县麦田的发生与为害。结果表明:田间小麦受害株率为30%~100%,幼虫平均密度4.8~105.6头/m 2,二者呈显著正相关关系。苗期至分蘖期为害小麦的草地贪夜蛾多为低龄幼虫(1~3龄幼虫比例为98.3%),拔节期低龄及高龄幼虫均有,抽穗至灌浆期为害小麦则以高龄幼虫为主(3龄以上幼虫比例达75.4%)。空间分布型分析表明,麦田草地贪夜蛾低龄幼虫呈聚集分布,高龄幼虫为均匀分布。进一步研究提出了基于幼虫密度及龄期的麦田草地贪夜蛾理论抽样模型和基于防治指标的序贯抽样技术。本研究明确了小麦田草地贪夜蛾发生为害的特点、空间分布特征和抽样方法,为田间种群密度调查和幼虫防治工作提供了技术支撑。

Fall armyworm,Spodoptera frugiperda(J.E.Smith)is an important invasive species in China.In this study,the damage on wheat and the spatial distribution of S.frugiperda in wheat fields were investigated in Xundian county,Yunnan province.The results indicated that the percentage of wheat damaged by S.frugiperda in the fields ranged from 30%to 100%,which significantly correlated with the average larval densities(ranged from 4.8 to 105.6 individuals per meter square).The early larvae at 1st to 3rd instar were frequently observed on wheat from seedling to tillering stages(the percentage was 98.3%)and late larvae used to be found in wheat jointing or filling stages(the percentage of larvae larger than 3rd instar reached 75.4%).Spatial distribution analysis indicated that the early larvae took a pattern of aggregation distribution and the late larvae exhibited an evenly distribution in wheat fields.Further,a theoretical sampling model based on larvae age and density and a sequential sampling technique in connection with larval control threshold were developed.This study indicates that S.frugiperda is an important pest in Chinese wheat productive system,and provides a technical support for population density survey and control of S.frugiperda in wheat fields.