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山楂红蜘蛛繁殖快,数量多,危害性大,是苹果等果树生产的劲敌。过去多年的化学农药防治效果不大。1985年春,我们调查山楂红蜘蛛虫口密度时,发现山楂红蜘蛛的天敌——丽草蛉大量活动。为了利用丽草蛉控制山楂红蜘蛛的成灾,对果园内80亩苹果树,未施用化学农药,观察丽草蛉和山楂红蜘蛛自然消长情况,以确定其能否成灾,于当年5月中旬至8月初调查结果如表1:
Hawthorn spider mites reproduce fast, the number of large, harmful, is the rival apple and other fruit trees. In the past many years of chemical pesticide control effect is not big. In the spring of 1985, when we surveyed the population density of hawthorn spider mite, we found that the spider mite hawthorn has a lot of activity. In order to control the disaster of hawthorn red spider by means of reticulate grass, chemical pesticides were not applied to 80 mu of apple trees in the orchard, and the natural growth and decline of spider mites and hawthorn were observed to determine whether they could cause disaster. In May of that year, The results from mid-August to early August are shown in Table 1: