The chemical signatures of mating in Cochliomyia hominivorax (Diptera: Calliphoridae): evidence for mating-induced remodeling of cuticular hydrocarbons

Abstract

The New World screwworm, Cochliomyia hominivorax (Diptera: Calliphoridae), remains one of the most economically important livestock pests in the Americas. Although wound-associated attractants and putative contact pheromones have been identified, little is known about how mating influences cuticular chemical signals associated with reproductive communication used for Sterile Insect Technique (SIT)-based eradication programs. Here, we characterized cuticular hydrocarbon (CHC) profiles of virgin and mated male and female C. hominivorax (J-06 strain) using gas chromatography–mass spectrometry and multivariate analyses. Twenty-one major hydrocarbons, consisting primarily of n-alkanes and mono- and dimethyl-branched hydrocarbons ranging from C23 to C37 , were detected across all treatment groups. Total hydrocarbon abundance did not differ among treatments; however, CHC composition differed significantly between sexes and was strongly influenced by mating status. Virgin males and females exhibited pronounced sexual dimorphism, with males enriched in lower-molecular-weight hydrocarbons and females characterized by greater relative abundances of longer-chain compounds. Mating-induced substantial shifts in CHC composition, particularly in females. The compounds contributing most strongly to these differences were predominantly methyl- and dimethyl-branched hydrocarbons implicated in mate recognition and reproductive signaling. These findings identify mating status as a previously unrecognized determinant of CHC composition, provide the first characterization of mating-associated variation in cuticular hydrocarbons in C. hominivorax, and identify candidate chemical signatures of mating that may contribute to female monogamy and provide candidate semiochemicals for future behavioral and functional studies.