Orientation cues of soybean aphid, Aphis glycines Matsumura, to plants

Through feeding and colonization, the soybean aphid Aphis glycines Matsumura (Hemiptera: Aphididae) has reduced soybean [Glycine max (L.) Merr.] yield. The soybean aphid is responsible for causing soybean deformities, such as reduced pod set and stunting, as well as transmitting plant disease. Plant resistance has been employed as a means of controlling aphid populations in soybean fields. This research was conducted to determine if soybean aphid could distinguish a resistant plant from a susceptible plant and if the aphid would travel towards a susceptible plant from a resistant plant. The experimental set-up included two plants separated by six inches within a 7"by 14" arena. Treatments included all combinations of resistant and susceptible plants among the two plants within the arena. Forty aphids were placed on the first plant and 24h were allotted for travel. At 24h, the number of aphids on each plant was counted under the microscope. Amongst apterous adults, more aphids moved onto the susceptible plant from the resistant plant than in any other treatment (Kruskal Wallis; p < 0.004). A Mann-Whitney test confirmed a difference between the test treatment (resistant to susceptible) and the treatment ranked second in the Kruskal Wallis test (resistant to resistant) (z < 0.001). No difference was observed in the treatments amongst first instar nymphs. Observed aphid behaviour is expected to help soybean breeders understand how resistance is affecting the soybean aphid.