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一、寄生情况的观察与调查粘虫〔Mythimna separata(Walker)〕是我省农业的重大害虫之一,在全省各发生区都以其第二代幼虫主要为害小麦、玉米。在研究我省粘虫第二代幼虫种群数量的变化规律中,常发现一些捕食性的天敌昆虫如步甲、虎甲和寄生性的天敌如姬蜂、绒茧蜂、寄生蝇和线虫等,对其有一定的抑制作用。据我们1980—1982年对我省宕昌、卓尼、临潭、临洮、甘谷等地的不完全调查及室内饲养观察的结果,我省第二代粘虫幼虫寄生性天敌的寄生率平均在23％左右。由于各地的施药水平不一,寄生率相差悬殊。如施药次数历年较高的临洮、甘谷城关地区,一般寄生性天敌寄生率仅6％左右;而在宕昌、卓尼、临潭等施药较少的地
I. Observation and investigation of parasitic conditions Mythimna separata (Walker) is one of the major pests of agriculture in our province. Wheat and corn are mainly harmed by the second-generation larvae in all districts of the province. In the study of the variation rule of population number of the second generation larvae of armyworm in our province, some predatory natural enemies, such as steppe, tiger armor, and parasitic natural enemies, such as myrmese, velvet bee, parasitic fly and nematode, It has a certain inhibitory effect. According to the results of incomplete surveys and indoor rearing observations of Dangchang, Zhuoni, Lintan, Lintao and Gangu provinces in 1980-1982, the parasitism rates of the parasitic natural enemies of second-generation armyworm larvae in our province were between About 23%. Due to the different levels of pesticide application, the parasitism rate is very different. For example, the parasitic rate of natural parasites is only about 6% in Linqu and Guanyu Chengguan areas with high application frequency over the past years; while in Dangchang, Zhuoni and Lintan,