十一星瓢虫种群动态及其对棉蚜的捕食功能

Population Dynamics and Predatory Function of Coccinella undecimpunctata to Aphis gossypii

十一星瓢虫是南疆棉田棉蚜的优势种天敌之一，田间调查表明：棉田中十一星瓢虫与棉蚜的变化关系密切，随着棉蚜数量的增加不断增加，7月15日瓢虫数量达1163头／百株，为全年最高峰；瓢蚜比由7月10目的1：305．94下降到7月15目的1：91．36，其发生高峰出现在棉蚜高峰后5d。麦田是十一星瓢虫重要的早期虫源地，应加以保护利用。室内试验结果表明：在不同的棉蚜密度下，幼虫及成虫对棉蚜的功能反应均符合HollingⅡ反应，当N→∞时，1～4龄幼虫和成虫最大日捕食量分别为17．42、46．73、96．15、151．52和144．93头，表明十一星瓢虫对棉蚜捕食潜力很大，尤其是3、4龄幼虫及成虫对棉蚜具有较大的捕食潜能。

Field observations indicated that populations of Coccinella undecimpunctata, one of the dominant species of natural enemies of Aphis gossypii in cotton fields in Southern Xinjiang, fluctuated closely with those of Aphis gossypii. Population size of C. undecimpunctata peaked at 1163 per 100 plants on July 15, and ratio of ladybird to aphids decreased from 1：305.94 on July 10 to 1：91.36 on July 15. Wheat field was found to be the main pool of the ladybird in early season. Functional response of C. undecimpunctata to A. gossypii fitted well with the models of HollingⅡ under different density of A. gossypii. Daily maximum predatory capacities of 1 - 4 instar larvae and adult on A. gossypii were 17.42, 46.73, 96.15, 151.52 and 144.93, respectively.