Re-investigation of cuticular hydrocarbons in imported fire ants: Evidence for a second type of hybrid Solenopsis fire ant?

Chemical analyses by GC-MS of hexane extracts from workers of Solenopsis invicta, S. richteri, and S. invicta * S. richteri hybrids revealed that cuticular hydrocarbons are species-specific. Workers of all fire ant species contain common, monomethyl, dimethyl, trimethyl-branched alkanes, and several alkenes. Analyses of the body chemical profiles of different fire ant populations from the southeastern US revealed a new type of hybrid fire ant (hybrid II), which is different from the hybrid type previously reported in the literature (hybrid I). The major components of cuticular hydrocarbons between hybrid I and II do not differ qualitatively. However, quantitative differences in some of the key components (i.e. heptacosane and 3-methylheptacosane) are recorded between the two hybrid types. The GC profile of cuticular hydrocarbons from the hybrid type II fire ant is reported in this paper for the first time.