ELECTROANTENNOGRAM RESPONSES OF THE CABBAGE SEED WEEVIL, CEUTORHYNCHUS-ASSIMILIS, TO OILSEED RAPE, BRASSICA-NAPUS SSP OLEIFERA, VOLATILES

Electroantennograms (EAGs) were recorded from male and female cabbage seed weevils (Ceutorhynchus assimilis Payk.) in response to volatiles isolated and identified from the odor of oilseed rape (Brassica napus ssp. oleifera DC. cv. Ariana). Relatively large EAGs were obtained on stimulation with volatiles produced by the oilseed rape crop at the time when seed weevils were actively searching for host plants. Artificial rape odor without certain key volatile compounds was in most cases significantly less stimulatory than odor containing these volatiles. There were significant differences in the EAG response of the sexes of C assimilis to the green leaf volatiles of oilseed rape and several terpenes present in rape flower odor. The importance of the qualitative and quantitative composition of host-plant odor in host location by C. assimilis is discussed.