To investigate the effects of mosquitofish, Gambusia affinis on aquatic insect biodiversity in South China, three common species of aquatic insects in mosquitofish habitat, I. E. , Cloeon bengalense, Chironomus kiiensis and Aedes albopictus, were selected under the lab condition to test the feeding preference of mosquitofish. The resulted showed that mosquitofish had no significant feeding selection on all preys in low density under the single-predator-and-multiple-preys experimental design. But mosquitofish preferred the larvae and pupa of A. Albopictus to other preys with the increase of prey density. When the prey ratio was 1' 1 under the single-predator-and-two-prey experimental design, mosquitofish frequently prefer larvae of A. Albopictus to the other prey. However, there was no significant influence to total prey consumption for mosquitofish when prey ratio was changed but total prey numbers unchanged. The results suggested that G. Affinis preferred to feed on the mobile prey close to water surface and showed no interest in the unmoving or dead prey, and mosquito larvae were the favorite prey of mosquitofish compared with mayflies and chironomids.%为了解食蚊鱼Gambusia affinis对华南地区水生昆虫多样性的影响,在实验室条件下,以食蚊鱼栖境中有代表性的3种水生昆虫为猎物,研究食蚊鱼的捕食选择性.结果表明,在单捕食者-多种猎物作用系统中,当猎物密度较低时,食蚊鱼对不同猎物的捕食选择性差异不显著.但随猎物密度的增加,食蚊鱼对白纹伊蚊Aedesalbopictus幼虫和蛹的捕食量明显增加,对摇蚊Chironomus kiiensis幼虫和蜉蝣Cloeon bengalense稚虫的捕食量下降.在单捕食者-2种猎物的作用系统中,在猎物比例相同的情况下,食蚊鱼更喜欢捕食白纹伊蚊幼虫；但是在猎物总数不变的情况下,改变猎物比例,对食蚊鱼总的捕食量影响不大.说明食蚊鱼喜欢捕食漂浮于水面上、会动的活体猎物,对死的或不动的猎物不敏感,且对蚊子幼虫具有明显的嗜好性.
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