1Lehrstuhl Tierphysiologie, Universität Bayreuth, 95440 Bayreuth, Germany.
2Umweltforschungszentrum Leipzig-Halle, Theodor-Lieser-Straße 4, 06120 Halle, Germany.
Aggression between members from different insect colonies may be a consequence of attempts to monopolise resources. Proximate factors that trigger and control the level of aggression may be of external and/or internal origin. When neighbours represent a smaller relative threat than strangers, as it is the case in many territorial systems, a reduced aggression between neighbouring colonies can be expected (dear-enemy phenomenon). For a comparative study we chose the termite genus Macrotermes in which all species are territorial. Recent work in M. subhyalinus provided no evidence for such a dear-enemy phenomenon (see poster: Jmhasly et al.). As a further example we chose M. falciger and correlated levels of aggression with inter-colonial differences in cuticular hydrocarbon compositions and neighbourhood. The results are: (1) Between colonies of M. falciger we found the full range of alarm and aggression, from no aggression between individuals up to pairings of individuals with overt aggression (death of most individuals). Aggression was rarely found within colonies. (2) In M. falciger we found three chemical phenotypes with clear differences in cuticular hydrocarbon compositions. With increasing differences in hydrocarbon compositions alarm and aggression increased. Both results are consistent with those from M. subhyalinus. (3) In contrast to M. subhyalinus, in M. falciger dear-enemy phenomena are an important proximate factor of aggression between colonies.