MECHANISM UNDERLYING CUTICULAR HYDROCARBON HOMOGENEITY IN THE ANT CAMPONOTUS-VAGU S (SCOP) (HYMENOPTERA, FORMICIDAE) - ROLE OF POSTPHARYNGEAL GLANDS

The aim of the present study was to investigate the regulation and the homogeneity of the chemical signature between members of Camponotus v agus after experimentally changing the cuticular chemical signature by topically applying hydrocarbons. Topical application of pentane (solv ent) to the cuticle of isolated workers led to a significant decrease in the quantities of the cuticular hydrocarbons measured within 3 hr, followed by an increase within the following 3 hr and a period of rela tive stability from 9 hr to 14 days. On the other hand, after topical application to isolated workers of n-tetracosane, a hydrocarbon existi ng only in trace quantity in this species, the quantity of this hydroc arbon measured over time in the epicuticular wax tended to level out a t about 14 days after treatment. In contrast, topically applied (Z)-9- tricosene, an unsaturated hydrocarbon not normally synthesized by this species, decreased dramatically within a few hours and had completely disappeared within 14 days. (Z)-9-Tricosene applied to one member of a group was present in the postpharyngeal glands of the other members from 30 min to seven days of cohabitation. The highest levels were rec orded in all six workers in each group after one day. GC-MS analyses s howed that (Z)-9-tricosene was present in the cuticles of some untreat ed workers only after four and seven days of cohabitation with a treat ed worker. These data suggest: (1) that the deposited (Z)-9-tricosene decreased very quickly on the cuticle of the treated worker, although the total amount was spread over the cuticle and postpharyngeal gland and (2) that it was absorbed by the nontreated workers via the postpha ryngeal glands during licking or grooming activities and reincorporate d into the cuticle at four and seven days. When the treated worker was separated from the other ants by a wire mesh, (Z)-9-tricosene was det ected neither in the cuticle nor in the postpharyngeal gland of nontre ated workers.