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桃蚜是上海地区桃树和蔬菜上的一个主要害虫,自一九六○年以来,由于长期使用乐果防治,桃蚜逐渐适应,虫体中的羧酸酯酶能够迅速将乐果水解,解毒成无毒或毒性较小的化合物,使桃蚜对乐果产生了抗药性。因此,近年来乐果的防治效果急剧下降,初期用20％乐果乳剂5000倍液已能获得良好的防治效果,如今改用40％乐果乳剂,浓度提高到2000倍,还不能控制为害。据悉,江苏、
Myzus persicae is a major pest on peaches and vegetables in Shanghai. Since 1960, due to the long-term use of dimethoate, Myzus persicae has gradually adapted, and the carboxylesterase in the parasites can rapidly hydrolyze dimethoate, Detoxification into non-toxic or less toxic compounds, the green peach aphid resistance to dimethoate. Therefore, the prevention and control effect of dimethoate has dropped sharply in recent years. At the early stage, 20% dimethoate emulsion 5000 times has obtained good prevention and cure effect. Instead of using 40% dimethoate emulsion, the concentration is increased to 2000 times and can not be controlled. It is reported that Jiangsu,