Olfactory responses of Aphidius gifuensis to odors of host plants and aphid-plant complexes

The olfactory responses of Aphidius gifuensis to odors from two host plants (Nicotiana tabacum and Brassica napus ssp.) and their complexes with different infestation levels of two host aphids (Myzus persicae and Lipaphis erysimi) were respectively examined in an olfactometer. The results showed that female A. gifuensis did not respond to odors of undamaged or mechanically damaged host plants, but significantly responded to odors of aphid/plant complexes. Moreover, A. gifuensis responded significantly to odors of both M. persicae and L. erysimi/plant complexes when host plants were infested by high levels of aphids, suggesting that quantity of aphid-induced volatiles could be important for attracting A. gifuensis. When tested between aphid/plant complexes, A. gifuensis did not show its preference for either complex. The efficiency of A. gifuensis against aphids in open fields potentially could be improved by using its olfactory response to aphid/plant complexes.