ELECTROANTENNOGRAM RESPONSES OF HYLES-LINEATA (SPHINGIDAE, LEPIDOPTERA) TO VOLATILE COMPOUNDS FROM CLARKIA-BREWERI (ONAGRACEAE) AND OTHER MOTH-POLLINATED FLOWERS

Electroantennograms (EAGs) from field-collected Hyles lineata moths we re recorded in response to 10 individual floral volatiles identified f rom Clarkia breweri (Onagraceae), to 22 scent compounds produced by ot her moth-pollinated flowers and to eight ubiquitous ''green leaf volat iles.'' Females' EAGs were generally 1.5- to 2-fold greater than those observed for male moths. Female:male EAG rank orders were significant ly correlated, but marked differences in order were observed for some compounds (e.g., benzyl alcohol, cinnamic aldehyde, geraniol, and lina lool). Linalool, benzyl acetate, methyl salicylate, and pyranoid linal ool oxide elicited the largest EAG responses (-1.2 to -0.8 mV) among s cent compounds from C. breweri. EAG responses were significantly lower for monoterpenes as a pooled compound class than for aromatic esters, alcohols and aldehydes, fatty acid derivatives, N-bearing compounds a nd oxygenated terpenoids. EAG responses to structurally related scent compounds were not significantly different in most cases. Both male an d female H. lineata were sensitive to most C. breweri scent compounds at 10(-2) to 10(-4) mu g/gl doses, and rank order in potency varied wi th the dose/concentration tested. H. lineara's olfactory sensitivity t o diverse volatile compounds across a range of doses/concentrations su ggests that a broad array of volatiles could function as floral attrac tants for foraging hawkmoths.