豆田棉铃虫分布型与经济阈值的研究

在鲁北豆田,棉铃虫Heliothis armigera(Hubner)已上升为主要食叶害虫。10项指标测定14个样本表明,该虫在豆田属聚集型分布。提出了“Z”字型10点抽样方式和不同密度下的合理抽样数量。室内饲养结果,食豆叶6龄共14.4天,平均食叶量12734毫米~2/头。利用田间人工接虫与模拟剪叶,并考虑天敌、费用等因素,建立了150～200公斤/亩范围内的经济阈值。

STUDIES ON DISTRIBUTION PATTERN AND ECONOMIC THRESHOLD OF HELIOTHIS ARMIGERA(HBNER) IN SOYBEAN FLELD

The cotton bollworm,Heliothis armigera(Hubner),has become the main leaf-eating pest in north of Shandong province.Determination of samples collected from 14 fields for 10 indices indicated that the population of its larvae in soybean field distributed in aggregated pattern,so a sampling way,10 points in Z form,and rational sampling numbers under different density of larvae were proposed.Laboratorial rearing showed that the larva had 6 instars,the larval stage prolonged for 14.4 days and the leaf-eating amount averaged for 12734 mm~2 per head.An economic threshold of heads for 10-13.3 kg/ha was established based on the results of simulated tests including artificial inoculation of larvae and cutting leaves in soybean fields,and considering the factors of natural enemy and control cost,etc.