Cuticular hydrocarbon profiles of dominant versus subordinate male Nauphoeta cinerea cockroaches.

Abstract

Interactions between male Nauphoeta cinerea cockroaches are characterized by an elaborate ritual that leads to a stable dominant-subordinate hierarchy between two individuals. Chemical signals involving volatile sex pheromones and cuticular hydrocarbons play an important role in establishing and maintaining dominance status. The present study was performed to identify cuticular hydrocarbons in two- and three-times dominant or subordinate individuals obtained by forcing dyadic encounters. Two methods, i.e., solid-phase microextraction (SPME) and organic solvent extraction, were used to isolate cuticular hydrocarbons. A total of 23 peaks of cuticular hydrocarbons were identified. Analysis showed quantitative differences in hydrocarbon profiles of three-times dominant and subordinate individuals according to extraction method and dominance status. Dominant individuals were characterized by higher proportions of the monomethylalkanes 11- and 13-MeC36, 13- and 15-MeC38, and 11-, 13-, and 15-MeC35, while subordinate individuals had higher proportions of the following monomethylalkanes: 7-, 9-. and 11-MeC31, 5-MeC31, 3- and 8-MeC32, and 9-, 10-, 11-, and 12-MeC32. Discussion focuses on the reliability of hydrocarbons as indicators of dominance status and on their correlation with physiological processes.