Olfactory responses of Rhopalosiphum padi to three maize, potato, and wheat cultivars and the selection of prospective crop border plants

Understanding host plant volatile – aphid interactions can facilitate the selection of crop border plants as a strategy to reduce plant virus incidence in crops. Crop border plant species with attractive odours could be used to attract aphids into the border crop and away from the main crop. As different cultivars of the same crop can vary in their olfactory attractiveness to aphids, selecting an attractive cultivar as a border crop is important to increase aphid landing rates. This study evaluated olfactory responses of the bird cherry-oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), to three cultivars each of maize [Zea mays L. (Poaceae)], potato [Solanum tuberosum L. (Solanaceae)], and wheat [Triticumaestivum L. (Poaceae)] with the aim of selecting an attractive crop border plant to reduce the incidence of the non-persistent Potato virus Y [PVY (Potyviridae)] in seed potatoes. Volatiles emitted by the crop cultivars were collected and identified using coupled gas chromatography/ mass spectrometry. Quantitative and qualitative differences were found among cultivars. Behavioural responses of alate R. padi to odours of the cultivars and synthetic compounds identified from the plants were determined with a four-arm olfactometer. Rhopalosiphum padi was attracted to odours emitted from maize cultivar 6Q-121, but did not respond to odours from the remaining eight crop cultivars. Volatile compounds from maize and wheat cultivars that elicited a behavioural response from R. padi and contributed to differences in plant volatile profiles included (Z)-3-hexenyl acetate (attractant) and a-farnesene, (E)-2-hexenal, indole, and (3E,7E)-4,8, 12-trimethyltrideca-1,3,7,11-tetraene (TMTT) (repellents). We conclude that maize cv. 6Q-121 is potentially suitable as a crop border plant based on the behavioural response of R. padi to the olfactory cues emitted by this cultivar. The findings provide insight into selecting crop cultivars capable of attracting R. padi to crop border plants.