HYDROCARBON DYNAMICS WITHIN AND BETWEEN NESTMATES IN CATAGLYPHIS-NIGER (HYMENOPTERA, FORMICIDAE)

The objective of the present study was to evaluate the interrelationsh ip between the cuticular and postpharyngeal glands' hydrocarbons, both in the individual ant and during its interaction with nestmates. In v ivo radiochemical assays were employed to monitor the de novo hydrocar bon biosynthesis from acetate in the ant's body. The newly synthesized hydrocarbons appeared first internally and after 24 hr they accumulat ed in the postpharyngeal gland and on the cuticular surface. Blocking the possibility of external transfer of hydrocarbons between cuticle a nd postpharyngeal gland led to a significant decrease of labeled hydro carbons in the postpharyngeal gland. In addition, during encounters be tween labeled and unlabeled ants, newly synthesized hydrocarbons were transferred, mainly via trophallaxis, but also by allo-grooming and ph ysical contact. In view of these results, we propose as a model for th eir dynamics that hydrocarbons are synthesized in tissues associated w ith the integument. Through self-grooming, there is a constant exchang e of hydrocarbons between the cuticular surface and the postpharyngeal gland. Furthermore, in encounters between nestmates, hydrocarbons are exchanged among them mostly by trophallaxis, with the mediation of th e postpharyngeal gland. Thus, this gland acts as a pool for mixing col onial hydrocarbons and may serve to attain a unified colony odor.