七星瓢虫和异色瓢虫对烟蚜及被寄生蚜的取食选择与气味反应

Feeding selectivity and odor response of Coccinella septempunctata and Harmonia axyridis to Myzus persicae(Sulzer) and parasitized M. persicae

【目的】研究2种捕食性瓢虫对烟蚜及被烟蚜茧蜂寄生烟蚜(以下简称寄生蚜)的取食选择和气味反应,为合理利用多种天敌昆虫组合防治烟蚜提供理论依据。【方法】在室内分别将不同寄生龄期的寄生蚜和等量未被寄生正常烟蚜(以下简称烟蚜)供给瓢虫取食,分别计算七星瓢虫和异色瓢虫成虫和4龄幼虫对烟蚜及寄生蚜的取食率;以烟蚜的不同虫态作为气味源,利用嗅觉仪测定2种瓢虫对寄生蚜气味的反应。【结果】七星瓢虫和异色瓢虫成虫均会取食1日龄和2日龄寄生蚜及烟蚜,且对二者的取食选择性无显著差异(P>0.05,下同);2种瓢虫成虫对3日龄和4日龄寄生蚜取食率显著低于烟蚜(P<0.05,下同),对该龄期寄生蚜的取食选择性较弱。七星瓢虫幼虫对2日龄寄生蚜和烟蚜的取食选择性无显著差异,但对4日龄寄生蚜的取食选择性显著低于烟蚜,取食后寄生蚜与烟蚜混合群体形成僵蚜的比例较高;异色瓢虫幼虫对较高日龄寄生蚜仍表现出明显的捕食,对2日龄和4日龄寄生蚜取食选择性与烟蚜均无显著差异,从而使取食后寄生蚜与烟蚜混合种群形成的僵蚜比例较低。七星瓢虫和异色瓢虫成虫除对烟蚜成蚜气味表现出明显的趋向反应外,还分别对僵蚜壳和寄生蚜表现出一定的趋向性。【结论】2种瓢虫成虫在低日龄寄生蚜和烟蚜间无明显的取食选择性,在高日龄寄生蚜和烟蚜间存在明显的取食选择性;七星瓢虫幼虫在2日龄寄生蚜和烟蚜间无明显的取食选择性,但对4日龄寄生蚜的取食选择性显著低于烟蚜;异色瓢虫幼虫在2日龄和4日龄寄生蚜与烟蚜间无明显取食选择性。2种瓢虫成虫对烟蚜成蚜气味的趋向作用强于寄生蚜和僵蚜。

【Objective】The feeding preference and odor response of two kinds of predatory ladybirds to Myzus persicae(Sulzer)and M.persicae parasitized by Aphidius gifuensis(reffered as parasitic aphids in the following part)were studied in order to provide a theoretical basis for the rational use of natural enemies to control M.persicae.【Method】Parasitic aphids of different parasitic ages and the same amount of normal aphids without parasitism(referred as aphids in the following part)were fed to ladybirds respectively in the laboratory,and the feeding rates of adult ladybirds and fourth instar larvae to M.persicae and parasitic M.persicae were calculated respectively.The response of two ladybirds to the odor of parasitic aphids was determined by olfactometer.Experiment using different states of M.persica as odor sources.【Result】Adult C.septempunctata and H.axyridis could feed on parasitic aphids and aphids of 1 or 2 instar.But there was no significant difference between the feed rate on parasitic aphids and aphids(P>0.05,the same below),the feed rate of C.septempunctata and H.axyridis on 3 and 4 instar parasitic aphids was significantly lower than on aphids(P<0.05,the same below)and the feeding selectivity on 3 and 4 instar parasitic aphids was weak.There was no significant difference in feeding selectivity of the larvae of C.septempunctata between the 2 instar parasitic aphids and aphids,but its feeding selectivity on 4 instar parasitic aphids was significantly lower than aphids.After eating,the proportion of mummied aphids was high in the mixed group of parasitic aphids and aphids.The larvae of H.axyridis showed prey on parasitic aphids with old instars,and showed no significant difference in feed selectivity between the 2 instar and 4 instar parasitic aphids,and finally led to the low rate of the mummied aphids in the mixed group of parasitic aphids and aphids.Adult C.septempunctata and H.axyridis showed an evident response to the odor of adult aphids,and also showed certain tendency to shell of mummied aphids and parasitic aphids.【Conclusion】There is no selectivity between the young instar parasitic aphids and aphids for adult C.septempunctata and H.axyridis,but evident selectivity between the old instar parasitic aphids and aphids.The larvae C.septempunctata show no feed selectivity between the 2 instar parasitic aphids and aphids,but its selectivity for the 4 instar parasitic aphids is significantly lower than aphids.There is no evident feed selectivity between the 2 and 4 instar parasitic aphids and aphids.Adult C.septempunctata and H.axyridis show stronger odor response to aphids than parasitic aphids and mummified aphids.