淮南棉区第2代棉铃虫种群密度较低的原因

通过田间调查、室内模拟试验以及人工辅助试验 ,探讨了雨水、天敌、作物布局和棉花生育期以及防治措施等对淮南地区第 2代棉铃虫种群密度的影响。结果表明 :大雨对棉铃虫卵有较强的冲刷作用 ,小雨淋湿棉叶对棉铃虫初孵幼虫以及较高的土壤湿度对棉铃虫蛹均有致命的打击 ;棉田四周面积较大的玉米作物是棉铃虫的主要食物源 ,棉花迟播迟栽对第 2代棉铃虫幼虫的钻蛀极为不利 ;天敌的捕食与寄生对第 2代棉铃虫种群的增长起到了重要的抑制作用 ,而不合理地使用化学农药则会削弱这种作用

Reasons for Lower Population Density of the 2nd Generation of Helicover-pa armigera in Cotton Region in South of Huaihe River

In order to inquire into the effect of rainwater, natural enemy, crop distribution, growth stage of cotton and control measures on population density of the 2nd generation cotton bollworm in cotton area in South of Huaihe River, field investigation, simulated experiment in laboratory and manual supplement experiment were conducted. The manifestations were as follows: heavy rain would scour the eggs of bollworm evidently. Drizzle was fatal to the larva just incubated and the higher soil humidity was fatal to the pupa. Large areas in relative of maize around cotton field was the main food source which attracted the bollworm. The measurements of late-sowing and late-transplantation in South of Huaihe River were detrimental for the larva of the 2nd generation bollworm to damage the cotton. Predation and parasitism of natural enemies played an important role in the control of cotton bollworm. But, unreasonable use of pesticide would weaken this function.