The Role of Cuticular Hydrocarbons in the Intraspecific Sexual Recognition Of Cyclocephala barrerai (Coleoptera: Melolonthidae).

A mixture of hydrocarbons of different molecular weights covers the Coleoptera cuticle, protecting the insects from desiccation and, in some cases, providing information about their physiological state. Courtship and mating in Cyclocephala barrerai Martínez begin when the male's antennae touch the female's thorax and elytra. The male antennae of C. barrerai have sensilla that detect hydrocarbons; however, the role of these compounds in the mating behavior of this beetle species remains unknown. Here, we analyzed the behavioral responses of both sexes of C. barrerai to conspecific cuticular hydrocarbons (CHCs) and identified them to determine how their composition varies by sex and age. CHCs were extracted from laboratory-reared C. barrerai individuals by immersion in hexane. We measured the percentage of adults that responded to CHCs extracts applied to a minimal visual component, a filter paper, an inert decoy, and a conspecific carcass stripped of CHCs. We identified and quantified the CHCs using gas chromatography coupled with mass spectrometry. Males exhibited arrestment, courtship, and copulation behaviors in response to CHCs extracted from females. The extracts contained nine compounds, seven of which were identified and six quantified. Insects emerged from the pupa with a similar amount of CHCs, and they differentiated as the gonads matured. Our results suggest that CHCs from C. barrerai females function as a contact sex pheromone.