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蚜茧蜂是麦田穗期麦长管蚜和黍缢蚜等蚜虫的主要寄生性天敌,一般年份被寄生的僵蚜率在5—10%,个别高的年份可达40%以上。笔者于1989年4月底到5月下旬,选择相距较远的麦田3块,每块田内随机取点30个,每点30穗,每5天调查一次,逐穗记载僵蚜数。将调查结果以4种聚集强度指标分析,表明僵蚜(即蚜茧蜂幼虫)在麦田一般为负二项分布,其聚集的原因主要是受环境(食料)因素所造成的.利用 Iwao(1971)提
Aphidius pulchricornis is the main parasitic natural enemy of aphids such as wheat aphid and wheat aphid in wheat field. The average incidence of parasitized aphids is 5-10% in some years and 40% in some high years. From the end of April 1989 to the end of May 1989, we selected 3 far wheat fields, each of which randomly took 30, 30 spikes each, and investigated every 5 days. The results of the survey were analyzed by four kinds of aggregation intensity indicators, indicating that the stiff aphid (ie, the larvae of Aphis gossypii) are generally negative binomial distribution in the wheat field, and their aggregation is mainly caused by environmental (food) factors. )mention