麦长管蚜为害损失及防治指标的研究

作者于1982—1984年对陕西关中麦区常发性的主要害虫麦长管蚜的数量消长与小麦产量损失的关系进行了测定,试验表明:在小麦整个生育期内均有该蚜虫为害,抽穗前蚜口增长缓慢,抽穗后蚜口急骤上升,灌浆期至乳熟期蚜口达最高峰。灌浆期间蚜害对小麦产量损失最严重,当百株蚜量1000头时,灌浆期受蚜害的损失率占全穗期同等蚜量为害损失的56.46—62.34%;占由扬花开始受害损失的72.6—88.23%。在灌浆期蚜量与产量损失率的关系式 y=0.9323x-1.4729。不同生育期喷药防治证明,以灌浆初期防治增产效果最佳,比不防治的千粒重增加8.2%,均比其它时期防治增产显著。据分析,在小麦扬花末期和灌浆初期是防治麦长管蚜的最适期。在500斤左右产量水平的麦田,其防治指标应为400—500头/百穗蚜量。

A Study of the Feeding Damage and Economic Threshold of English Grain Aphids (Homoptera Aphidae)

English grain aphids(Macrosiphum avenae(Fabricius)is one of the major pests in central Shaanxi Plain.The correlation between the yield loss of wheat and the dynamics of aphid population in the field had been cvaluated by the authors in the years 1982-1984.The system- atic survey and experiments indicate that the pest occurs throughout the whole growing season of winter wheat.The population of the aphid increases slowly before ear emergence of the plant,but goes up abruptly after that.During the milky stage to soft dough stage,the aphid number reaches maximum.The milky stage feeding makes most severe wheat yield loss,e.g.when the population level was kept at 1000 aphids per 100 plants,the damage ratio of milky stage feeding to the whole-ear stage feeding was 56.46-68.34%,and of flowering stage feeding to the whole-ear stage feeding was 72.6-88.23%. In the milky stage,the correlative formula between aphid population and the wheat yield loss is Y=0.9323X-1.4729.Spraying insecticide in the different stage indicates that the early milky stage treatment produces the best effect on the yield,per 1000 grain weight increased 8.2% when compared with thc nonsprayed treatment(CK),Statistical analysis shows that the later flowering stage and/or the early milky stage are the best time for insecticide spraying to control English grain aphids,and the economic threshold for 500 jin/mu yield level wheat field is 400-500 aphids per 100 ears.