The role of cuticular hydrocarbons in intraspecific aggression in the invasive antCardiocondyla obscurior

Abstract

AbstractCuticular hydrocarbons (CHCs) are important cues for nestmate discrimination and intraspecific aggression in ants. In invasive ants, diminished CHC profile diversity is suspected to contribute to the ecological and evolutionary success of populations by reducing intraspecific aggression between colonies. The antCardiocondyla obscuriorhas successfully colonized habitats around the world, reaching high local population densities. However, despite being invasive, colonies still react aggressively against each other, especially in interactions with non-nestmate alate queens. Here, we study whether CHCs are relevant for antagonistic interactions in this species, by combining behavioral experiments with gas-chromatography coupled with mass spectrometry (GC-MS). We show that queen and worker CHC profiles show pronounced quantitative as well as qualitative differences, that queens with depleted CHC profiles receive virtually no aggression from non-nestmates, and that aggression levels are positively correlated with the naturally occurring CHC profile differences between colonies. These findings provide first empirical evidence for a role of CHCs and chemical diversity in antagonistic behaviors against foreign queens in this species. They further suggest that invasive populations ofC. obscuriorare multicolonial and polydomous.