小油菜播种期与密度对黄条跳甲危害程度的影响

在青海西宁地区，小油菜３月２１日～４月２０日播种，密度为４５、７５、１０５、１６５、２２５万株／ｈｍ２。黄条跳甲危害随播期推迟而加重，种植密度大，危害重。危害小油菜的黄条跳甲主要是黄宽条跳甲，其次为黄曲条跳甲，二者比例为３．３∶１。

A preliminary study on the occurrence of striped flea beetles under different sowing time and density of spring rape ( Brassica campestris L.)

This paper reports striped flea beetles occurred in different sowing times and densities of spring rape. The results obtained from 4 sowing times and 5 sowing densities indicated striped flea beetles damaged rape seedlings increasingly when sowing time was postponed and sowing density was enlarged. There were 2 kinds of the beetles which damaged spring rape in Xining, dominant species was Phyllotreta humilis , another was P.vittata , with a ratio of 3.3 to 1. It's very important to begin sowing early properly and to control sowing density strictly in order to diminish the pests.