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棉铃虫在鲁西北地区一年发生4代,一代主要在小麦上发生为害,一般每平方米有虫0.1—1.0头,形不成明显的为害,1992年大暴发,一般每平方米有虫10—15头,多的50头以上,小麦受害减产5％左右。二代主要在春棉上,百株累计落卵6000—10000粒,(往年500—700粒),多的达15000粒以上,寄主范围之广,数量之多,为害程度之重,是历史上从未有过的,棉花、玉米、大豆、花生、蔬菜、苹果、枣、梧桐、西瓜等均受为害,棉花顶心受害率86％-95％,有的拔了棉苗改种玉米等其他作物;玉米受害株率95.6％,大豆受害株率92.3％;苹果顶梢受害率90.2％;枣果受害率20％左右,造
The cotton bollworm occurs in the northwest of Shandong Province for 4 generations a year. The generation mainly occurs on the wheat. Generally, there are 0.1-1.0 insects per square meter, which can not form obvious damage. In 1992, there was a large outbreak of 10- 15 heads, more than 50 heads, wheat yield reduction of about 5%. The second generation is mainly on spring cotton. One hundred strains accumulate 6000-10000 grains (500-700 grains in previous years), more than 15000 grains more than others. The host range is wide and the quantity is large. We have never had cotton, corn, soybeans, peanuts, vegetables, apples, dates, sycamore, watermelon and so on. The top damage rate of cotton is 86% -95% Crops; Damage rate of corn plants 95.6%, soybean strain rate of 92.3%; apple top damage rate of 90.2%; jujube damage rate of 20%