Expansion Strategies of a North American Termite Species Introduced in France (Isoptera: Rhinotermitidae)

Abstract:
Reticulitermes santonensis (Rhinotermitidae) is a subterranean termite that infests urban areas in France where it causes serious economic damages. It is largely accepted that French populations of R. santonensis have been founded by the introduction of a North American species, R. flavipes. Understanding the expansion strategies of an introduced species in a new environment is important to improve its population control. In this study, we performed a comparative analysis of the social structure of R. santonensis with an endemic species, R. grassei. All samples were collected on the island of Oléron where the two species live in sympatry. We are presenting three main results: (1) Using behaviour tests, we show that colonies of R. santonensis often fuse during intraspecific encounters, and seem to dominate colonies of R. grassei. By contrast, R. grassei colonies show a strong intraspecific aggressiveness and consequently do not fuse. (2) Chemical analysis of the cuticular hydrocarbons indicates that R. santonensis colonies possess a chemical homogeneity, whereas the chemical signature of R. grassei colonies presents important variations within populations. (3) Preliminary genetic analyses reveal that R. santonensis colonies are vast and possess more than two reproductives. These results show that the social structure of native and introduced species strongly differs, and suggest that R. santonensis presents some advantages over R. grassei to spread in its environment.