Diet-derived male sex pheromone compounds affect female choice in a noctuid moth

Sexual signals often function in species recognition and may also guide mate choice within a species. In noctuid moths, both males and females may exercise mate choice. Females of the tobacco budworm Chloridea virescens prefer to mate with larger males, but the signal(s) underlying female choice remain unknown. Male hairpencil volatiles are emitted during close range courtship displays. However, previously identified male hairpencil volatiles, namely acetate esters, aldehydes, alcohols, and fatty acids, are not associated with female choice. Recently, two new hairpencil compounds were identified that elicit strong electrophysiological responses in female antennae: methyl salicylate (MeSA) and delta-decalactone. In this study, we investigated the effect of larval diet and adult feeding on MeSA and delta-decalactone content in hairpencils and determined whether these compounds are involved in female choice. We found that larval diet affected MeSA content in hairpencils, but not delta-decalactone. Conversely, adult feeding affected the level of delta-decalactone, but not MeSA: sugar-water feeding increased delta-decalactone content compared to plain water. In two-choice assays, females mated more with males that had higher amounts of delta-decalactone, and less with males with higher amounts of MeSA.