Qualitative and quantitative differences in cuticular hydrocarbons between laboratory and field colonies of Pogonomyrmex barbatus.

Ants held in the laboratory and field ants of the species Pogonomyrmex barbatus have quantitative differences in their cuticular hydrocarbons and a qualitative difference in their methyl-branched hydrocarbons. Laboratory-held workers showed twice the hydrocarbon content as field ants. This difference was mainly due to higher amounts of straight-chain alkanes and methyl-branched alkanes in laboratory ants, whereas the proportion of the alkenes remained the same for both groups. In addition to the absence of some hydrocarbons in the field colonies, one of the methyl-branched hydrocarbons differed in amount and branching pattern between the two groups of ants. Whereas, notable peaks of 2-methylalkanes were identified in ants kept in the laboratory, these compounds could not be identified in ants living in their natural habitat. However, a trace amount of 4-methyltriacontane was found in lieu of the 2-methyltriacontane counterpart in field ants. Possible explanations for both qualitative and quantitative differences are discussed.