棉花蚜螨繁殖率及棉蚜再猖獗

氰戊菊酯曾对棉蚜有极好的防治效果,而对棉叶螨防治效果极差。棉蚜抗药性的发展使药效发生了变化,近来的试验表明,该药对蚜虫药效很差,对伏蚜根本无效,１００和２００ｐｐｍ对棉蚜已属低浓度,可使其繁殖率增加４－８倍,在田间使用氰戊菊酯可形成大的棉蚜群体。在相同浓度下一般可抑制棉叶蚜群体,使药后存活很少的棉叶螨在种间竞争中处于劣势而使群体越来越小。氰戊菊酯的复配剂－丰收菊酯弥补了氰戊菊酯的不足,可同时控制蚜

MONITORING ON THE REPRODUCTION RATE OF COTTON APHID AND CARMINE SPIDER MITE ON COTTON AND THE RESURGENCE OF COTTON APHID UNDER PYRETHROIDS PRESSURE

In early 1980s,fenvalerate had deen highly effective on cotton aphid Aphis gossypii Glover but ineffective on carmine spider mite Tetranychus cinnabarinus Koch.Its efficacics changed significantly as the resistance of cotton aphid increased.The results of late tests showed that it was already very poor for controlling aphid,and the summer type cotton aphid was even no mortality reactity reaction to it.Application with 100 and 200 ppm of fenvalerate the lower concentration to cotton aphid, could cause the population increase 4-8 times after such treatment. The field application of fenvalerate caused rapid development of cotton aphid population,whilst under the same concentration treatment,the reproduction of carmine spider mite was suppressed,and showed certain ovicidal action.Through the application of fenvalerate on the complex population of aphid and mite,the high cotton aphid population in this inter-specific competition made the inferior one of carmine spider mite became smaller and smaller."Fengshou",a mixture of fenvalerate and monocrotofos had remedied the defect of fenvalerate,it suppressed thepopulation increase of both aphid and mite simultaneously,and overcame the resurgence of the two pests.