Behavioral and electrophysiological responses of cabbage aphids to odors from host plants infested by conspecific and heterospecific herbivores

Behavioral and electrophysiological studies on aphid responses to host plant odors, although important, are still not exhaustive for some species. Moreover, most studies have not focused on whether these responses are mediated by odors from plants infested by conspecific and heterospecific individuals. Here, our goal was to identify the chemical cues involved in the attraction of the cabbage aphid (Brevicoryne brassicae L.) to cabbage plants. To achieve this, we collected volatiles emitted from uninfested cabbage plants, cabbage plants infested by either B. brassicae (conspecifics) or by diamondback moth (Plutella xylostella) larvae (heterospecifics), and from aphids alone. Choice tests revealed that B. brassicae were mostly attracted to odors from conspecific-infested cabbage plants; however, they also showed attraction to odors from uninfested plants and plants infested by P. xylostella larvae and were least attracted to odors from aphids alone. Using coupled Gas chromatography-Electroantennographic detection studies (GC-EAD) and Gas chromatography–Mass spectrometry (GC–MS), we revealed some chemically active compounds that elicited B. brassicae olfactory response, with more of these compounds in the cabbage plant infested by conspecific than in the rest of the treatments. It is possible that the knowledge gained from this work could pave the way for synthetic lures as an integrated pest management approach for B. brassicae. Therefore, more studies would need to be conducted to validate and isolate those exact compounds that positively excited the cabbage aphids’ olfactory response.