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魏县棉花年播种面积25万亩以上。但产量低而不稳,徘徊不前。究其原因主要是棉铃虫为害所致。五十年代棉铃虫在魏县发生很轻,基本不用防治。进入八十年代,棉铃虫猖獗发生,防不胜防,难以控制。造成大面积减产,严重挫伤了棉农的积极性。进入九十年代连年大发生,1991年7月25—26日,在魏县魏城镇调查,棉花单株落卵量30—40粒。幼虫成活率70％以上,严重地块棉铃被害率高达40—50％。从气象、植被、人为等生物和非生物因素进行的调查、统计分析;长期单一使用一种化学农药,使棉铃虫产生了抗药性,是猖獗发生的根本原因。如六十年代以前,以六六六、滴滴涕等有机氯农药为主防治棉铃虫,控制了较长一段时间,但是由于单一使用有机氯农药,使棉铃虫产生了抗药性。七十年代初只好改用1605、亚胺硫磷等有机磷农药防治棉铃虫,七十年代末、八十年代初,棉铃虫再度产生抗药性,致使再度猖獗
Weixian cotton planting area of 250000 acres or more. However, the output is low and unstable, stagnating. The main reason is the damage caused by cotton bollworm. Fifties cotton bollworm occurred in Wei County is light, the basic need of prevention and treatment. Into the eighties, cotton bollworm rampant, unavoidable, difficult to control. Resulting in large-scale production cuts, seriously dampening the enthusiasm of the cotton farmers. Into the nineties occurred in successive years, July 25-26, 1991, Weicheng Wei Chengzhen survey, the number of cotton eggs per plant 30-40. Larva survival rate of more than 70%, severe block boll damage rate as high as 40-50%. According to the survey and statistical analysis of biological and abiotic factors such as meteorology, vegetation and human activities, the long-term single use of a chemical pesticide has made the cotton bollworm resistant and is the root cause of rampant occurrence. For example, prior to the 1960s, the control of cotton bollworms with hexachlorocyclohexane, DDT and other organochlorine pesticides was controlled for a long period of time, but due to the single use of organochlorine pesticides, the cotton bollworm developed resistance. The early seventies had to switch to 1605, imidacloprid and other organophosphate pesticides to control cotton bollworm, the late seventies, early eighties, cotton bollworm again produce resistance, resulting in rampant