Submitted to: Journal of Chemical Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/21/2004
Publication Date: 12/1/2004
Citation: Florane, C.B., Bland, J.M., Husseneder, C., Raina, A.K. 2004. Diet mediated inter-colonial aggression in the Formosan subterranean termite, Coptotermes formosanus. Journal of Chemical Ecology. 30: 2561-2576. Interpretive Summary: Termites like many other social insect species exhibit aggressive behavior between individuals of different colonies. However this behavior is not consistent. In case of the Formosan subterranean termite, the factors that may be responsible for evoking aggression were ambiguous. We investigated genetic relatedness and surface chemicals of different colonies as possible factors but found no correlation with aggression. However, feeding on different types of wood did lead to aggression. Following feeding on a different wood, the chemical profile of termites changed, and this may be the factor responsible for evoking aggression. The information will be useful in understanding ecology and foraging behavior of the Formosan subterranean termite. It will also provide an insight into colony expansion and merger of different colonies.
Technical Abstract: In most social insects, intercolonial and interspecific aggression is an expression of territoriality. In termites, cuticular hydrocarbons (CHCs) have been extensively studied for their role in nestmate recognition leading to aggressive discrimination of non-nestmates. More recently, molecular genetic techniques have made it possible to determine relatedness between colonies and investigate the influence of genetics on aggression. In the Formosan subterranean termite Coptotermes formosanus, however, the role of CHCs and genetic relatedness in intercolony aggression has been ambiguous, suggesting the involvement of additional factors in nestmate recognition. In this study we assess the range of aggression in this termite species and characterize the influence of genetic relatedness, CHC profiles and furthermore the termites' diet on aggression levels. We collected four colonies of C. formosanus feeding either on bald cypress or birch from three locations in Louisiana. Intercolony aggression ranged from low to very high. Differences in CHC profiles as well as genetic distances between colonies determined by using microsatellite DNA markers showed no significant correlation with aggression. However, termite diet (host tree) played a significant role in determining the level of aggression. Thus two distant colonies each feeding on different diets showed very high aggression which significantly diminished if they were fed on the same wood in the laboratory (spruce). Using headspace solid phase microextraction, we found three compounds from workers fed on birch that were absent in spruce fed individuals. Such diet derived chemicals may be involved in the complex determination of nestmate recognition in C. formosanus.