SITONA LINEATUS HOST-PLANT ODORS AND THEIR COMPONENTS - EFFECT ON LOCOMOTOR BEHAVIOR AND PERIPHERAL SENSITIVITY VARIATIONS

Adult Sitona lineatus L., (Coleoptera: Curculionidae) feed on the leav es of various species of leguminous plants, and females lay in the vic inity of pea plants, the roots of which are eaten by the larvae. A stu dy of the volatiles from several legumes and of the response of S, lin eatus individuals to these substances was undertaken using two complem entary techniques: behavioral, to study the locomotory orientation; an d electrophysiological, using electroantennography (EAG). Four volatil e compounds, cis-3-hexen-1-ol, 2-hexenal, cis-3-hexen-1-yl acetate, an d 3-octanone, were identified from pea, vetch, clover, and lucerne, by coupled gas chromatography-mass spectrometry (GC-MS) and coupled gas chromatography-infrared spectrometry (GC-IR). After emergence from Jul y to mid-November, the image display high response to the odor of pea and some other leguminous plants. A second period of enhanced sensitiv ity was observed during crop colonization from March to May. High EAG response to pea odor and cis-3-hexen-1-yl acetate was correlated with periods of enhanced locomotory orientation during these months. Experi mental results indicate that cis-3-hexen-1-yl acetate could play a key role in discriminating pea among other acceptable leguminous species.