甘蓝蚜危害油菜产量损失的研究

作者用一种衡量蚜虫危害的新尺度——“累计蚜量(头/天)”,对油菜不同生育阶段的单株损失及补偿作用分别作了研究。结果表明:油菜苗期、苔花期、荚果期都存在着一个造成损失的临界危害量(C)。苗期 C 为360～440(头/天),苔花期 C 为13500～16500(头/天),荚果期 C 为2700～3300(头/天)。危害量与损失率的关系符合 logistic 曲线。根据研究结果提出“有害株”的概念,既有蚜虫而又影响产量的植株。并结合蚜虫消长规律及累计蚜量的计算原理推导出确定“有害株”蚜量标准的公式B=C/(1/2)T(1+Q~n)+ITQ(1-Q~(n-1))/(1-Q)经比较,认为“危害株率”是蚜虫防治指标理想的尺度,它不仅明确可靠,而且简单易行。

STUDY ON THE YIELD LOSSES OF COLESEED CAUSED BY THE CABBAGE APHID,BREVICORYNE BRASSICAE (LINNAEUS)

A new scale-the accumulated number of aphids (days of infesta-tion×number of the insects per day,or aphid days)-was used in experiments to measure the damage caused by the cabbage aphid Bre-vicoryne brassicae (L.)].Losses caused by the damage at different stages of individual rape plants and their compensating ability were studied respectively,The results indicate that there exists a critical number (C) at each stage of rape growth to cause yield losses.C of the seedling stage=360~440 aphid (days).C of the flowering stage=13500~16500 aphid (days).C of the podding stage=2700~3300 aphid (days).The relationship between the accumulated infestation numbers and the yield losses corresponds with the logistic curve.