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为害苹果的苜蓿红蜘蛛(Bryobia praetiosa Koch.)及山楂红蜘蛛(Tetranychus viennensis Zacher),近年来已成为我国苹果的严重害虫。在辽东半岛及胶东半岛等主要苹果产区,每年因红蜘蛛的为害,影响苹果的产量很大,同时付出了很大的防治费用。如山东烟台市幸福公社五大队的苹果,最近三年来因遭受红蜘蛛的为害影响产量,每年平均达20％左右,三年减产估计在五百万斤上下,而每年为防治红蜘蛛的农药费平均每亩即需20元左右。更值得注意的是,各地普遍存在大量用药防治其他果树害虫之后,红蜘蛛有明显的发展趋势,尤其大量施用残效
Bryobia praetiosa Koch. And Tetranychus viennensis Zacher have been the serious pests of apple in China in recent years. In the main apple producing areas such as Liaodong Peninsula and Jiaodong Peninsula, the annual production of apple spiders is affected by the red spider, which results in a large output of apples and a great cost for prevention and treatment. For example, the apple of the 5th Brigade in Yantai City, Yantai City, Shandong Province, has been affected by the damage caused by the red spiders in recent three years, with an average annual rate of about 20%. The estimated annual reduction in three years is about 5 million jin. However, An average of about 20 yuan per mu. More noteworthy is that there are widespread drug control around the other fruit pests, the spider has a clear trend of development, especially the large number of residual effects