BEHAVIORAL AND ELECTROPHYSIOLOGICAL RESPONSES OF APHIDS TO HOST AND NONHOST PLANT VOLATILES

Alate and apterous virginoparae of Aphis fabae Scop. and alate virginoparae of Brevicoryne brassicae (L.), walking in a linear track olfactometer, were attracted by odor from leaves of their host plants. A. fabae responded to odor from undamaged but not damaged bean leaves. Gynoparae (autumn migrants) of A. fabae, however, did not respond to their host plant (spindle, Euonymus europaeus) odor. Odors of certain nonhost plants masked the attractiveness of the host plant leaves, but tansy (Tanacetum vulgare) and summer savory (Satureja hortensis) volatiles repelled B. brassicae and A. fabae, respectively. 3-Butenyl isothiocyanate attracted B. brassicae and Lipaphis erysimi (Kalt.), the latter species being more sensitive in both behavioral and electrophysiological studies. Isothiocyanate receptors were found on the antennae of A. fabae, which was repelled by these compounds, 4-pentenyl isothiocyanate being the most active.