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1980—1982、1984—1985年在河北省饶阳县的不同土壤肥力水平、不同棉花品种上进行了模拟为害和自然为害试验,旨在确定第三代棉铃虫 Heliothis armigera (Hubner)虫口密度与棉花产量之间的关系。结果表明,棉花对于第三代棉铃虫为害的补偿能力较弱。较好的土壤肥力亦不能促使棉株完全补偿三代期间的受害损失。每亩皮棉减产斤数Y与第三代百株累计卵量E_3的关系为:Y=-0·2801+0.0643E_3。根据防治的直接收益与直接代价,算出了第三代棉铃虫的经济阈值为百株累计卵量35粒,这一阈值可适用于不同肥力水平的地块。
1980-1982-1985-1985 in Raoyang County of Hebei Province in different soil fertility levels, different cotton varieties were simulated damage and natural damage experiments to determine the third generation of cotton bollworm Heliothis armigera (Hubner) population density and cotton The relationship between yield. The results showed that cotton was less able to compensate for the third generation of cotton bollworm damage. Better soil fertility also did not prompt cotton plants to fully compensate for victimization losses during the three generations. The relationship between the yield of cotton lint per acre Y and the cumulative egg volume E_3 of the third generation of one hundred plants is Y = -0.2801 + 0.0643E_3. According to the direct benefits and direct costs of prevention and control, the economic threshold of the third generation of cotton bollworm was calculated to be 35 grains per 100 oval eggs. This threshold can be applied to plots of different fertility levels.