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 were recorded in response to 10 individual floral volatiles identified from Clarkia breweri (Onagraceae), to 22 scent compounds produced by other moth-pollinated flowers and to eight ubiquitous ''green leaf volatiles.'' Females' EAGs were generally 1.5- to 2-fold greater than those observed for male moths. Female:male EAG rank orders were significantly correlated, but marked differences in order were observed for some compounds (e.g., benzyl alcohol, cinnamic aldehyde, geraniol, and linalool). Linalool, benzyl acetate, methyl salicylate, and pyranoid linalool oxide elicited the largest EAG responses (-1.2 to -0.8 mV) among scent 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 and oxygenated terpenoids. EAG responses to structurally related scent compounds were not significantly different in most cases. Both male and 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 with the dose/concentration tested. H. lineara's olfactory sensitivity to diverse volatile compounds across a range of doses/concentrations suggests that a broad array of volatiles could function as floral attractants for foraging hawkmoths.