|Vander Meer, Robert - Bob|
Submitted to: Naturwissenschaften
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2004
Publication Date: 3/26/2004
Citation: Katzav-Gozansky, T., Boulay, R., Vander Meer, R., Hefetz, A. 2004. In-nest environment modulates nestmate recognition in the ant Camponotus fellah. Naturwissenschaften. p. 1-10. Interpretive Summary: A key element in the success of ants is that a colony's queen(s) is usually shielded from outside intrusions of pathogens and parasites by large numbers of sterile workers. Nestmate recognition (recognition of other members of your colony) maintains this colony insularity, thus workers from each colony of a given species may behave aggressively toward workers from another colony and compete for territory and resources. Our understanding of the nestmate recognition system is still rudimentary. Scientists at the Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida and the Department of Zoology, Tel Aviv University, Tel Aviv, Israel, through a U.S.- Israel Binational Science Foundation grant demonstrated for the first time that nest-volatiles affect nestmate recognition, and that the nestmate recognition process is governed by more than hydrocarbons found on the cuticle of worker ants. This work broadens the search for compounds that modify nestmate recognition behavior. Understanding nestmate recognition in ants may lead to better ways to get pathogens and parasites past the formidable defences of pest ants, such as the fire ant, Solenopsis invicta.
Technical Abstract: Multiple behavioural and chemical studies indicate that nestmate recognition cues are low-volatile substances that reside on the cuticular surface. We tested the hypothesis that nest environment, in particular nest volatile odours, can modulate nestmate recognition-mediated aggression. Workers of Camponotus fellah were isolated within their own nest by confining them in small cages composed by either single (SM) or double mesh (DM) screening. Individual workers isolated outside their nest served as control. SM workers could maintain limited physical contact with their nestmates, while DM workers were exposed to nest volatiles only. When reintroduced into a group of 50 nestmates, the totally isolated workers were treated as alien ants whereas the SM workers were treated as nestmates. Aggression towards DM ants depended on the period of isolation. Only workers isolated for over two months were aggressed by their nestmates, which did not significantly differ from totally isolated nestmates. Cuticular hydrocarbon (HC) profiles did not completely correlate with the behavioural data. Contrary to prediction from the bioassay, the profiles of both SM and DM ants were clearly distinct from that of the non-isolated ants. However, they were also distinct from the isolated ants. This indicates that nest environment affected label-template mismatch through modulating aggressive behaviour, as well as the direction at which cuticular HCs diverged during the separation period. In a second experiment we tested whether alien odour habituation can modulate nestmate recognition. Queenright (QR) and queenless (QL) groups were housed together with or without limited contact and odour flow between the groups. Both QR and QL resident ants were equally aggressive towards alien ants with which they had no prior contact. However, when limited contact and odour flow were possible, QR, but not the QL workers showed highly elevated aggression, compared to the non-contact ants. We suggest that nest volatiles modulate the ants' aggressive behaviour in a queen-dependent manner, either by affecting their motivation or by affecting nestmate recognition cues. This study demonstrates for the first time that factors other than label-template mismatch affects nestmate recognition, and directs attention to nest-volatiles as possible modulators.