Regulation of the chemical signatures of two termite species, Reticulitermes santonensis and Reticulitermes lucifugus grassei, living in mixed experimental colonies

Abstract

Each of the two termite species Reticulitermes santonensis and Reticulitermes lucifugus grassei has its own distinct chemical signature, on which the intra- and inter-species recognition processes are based. When the 2 species were kept together in artificially mixed colonies, changes in their chemical signatures were observed after only 2 h of cohabitation: each species acquired all the hydrocarbons specific to the other species, but R. lucifugus grassei acquired larger amounts of the R. santonensis hydrocarbons than vice versa. After a 24 h period of cohabitation, both the homospecific and allospecific signatures carried by all the individuals were in the same proportions as those characterizing the individuals of the 2 species prior to cohabitation. The other species' signature was therefore acquired additively, probably via physical contacts between the cohabiting individuals. After 14 days of cohabitation, however, changes in the amounts of some of the components synthesized by each species were observed, and the allospecific signature also differed from that acquired at the beginning of the experiment: a regulatory process involving quantitative changes in only some of the cuticular components was therefore at work. The results obtained with this artificially mixed colony model show that the hypotheses put forward up to now by previous authors about regulatory mechanisms of this kind are not in fact mutually exclusive, but may be applicable to various successive periods of cohabitation.