棉蚜种内竞争对其种群数量的影响

棉蚜在每株接种2，4，8，16，32头等不同初始密度情况下的种群数量变化进行了实验观察，并对有翅蚜的数量动态进行了观察和分析。棉蚜增殖速度有随初始接种密度的增大而显著降低，而且随着繁殖时间的增加而加强趋势。在接种2周后，有翅蚜占总蚜量的比例在接种密度为8头/株时达到最高，之后开始迁飞，但到接种3周后，最高比例出现在接种密度为16头/株，说明有翅蚜的产生与迁飞不但受种群密度的影响，且受其它因子的影响。

Effect of Intra specific Competition on Population\;Dynamic of the Cotton Aphid, Aphis Gossypii

The population dynamic of the cotton aphids, Aphis gossypii Glover, under varying inoculated densities by 2,4,8,16 and 32 aphids per plant, was observed in the gauze covering cage in June, 1998. The alate population was observed and analyzed. The cotton aphid population increased significantly with the downward inoculated densities and with the time. At the age of two weeks after inoculation, the highest ratio between alate and total aphids occurred under the density of 8 per plant and emigrated thereafter. But at the age of three weeks, the highest ratio switched to the density of 16 per plant. The result showed that the development of alate in the cotton aphid was not only affected by the density of aphids (crowd) but also by other factors.