Chemistry and functions of exocrine secretions of the antsTapinoma melanocephalum and T. erraticum

Abstract

Volatile constituents produced by ant workers belonging to the speciesTapinoma melanocephalum andT. erraticum have been analyzed by gas chromatography-mass spectrometry. The pygidial (=anal) gland secretion ofT. melanocephalum is fortified with 6-methyl-5-hepten-2-one and actinidine (the mass spectrum of which is corrected in this paper). An unidentified compound was detected in cephalic extracts. The pygidial gland secretion ofT. erraticum was also dominated by 6-methyl-5-hepten-2-one, in addition to two isomers of iridodial, and iridomyrmecin. The sternal glands contained iridodial and C15-C20 hydrocarbons. Workers ofT. melanocephalum effectively utilize their pygidial gland secretions as an alarm-defense system during aggressive encounters with workers ofSolenopsis geminata. 6-Methyl-5-hepten-2-one is active as a releaser of alarm behavior, and actinidine is repellent to workers ofT. melanocephalum. Cephalic extracts possessed attractant and arrestant properties for workers of this species.

Chemical signals associated with life inhibit necrophoresis in Argentine ants

“…Dolichodial and iridomyrmecin are produced and stored in the pygidial gland of L. humile (15,16), and this gland occurs in all ant subfamilies except the Formicinae, where it may have been lost secondarily (17,18). Volatile chemicals produced by the pygidial glands of dolichoderine and myrmicine ants are commonly thought to have alarm or defensive functions (19)(20)(21), and the less volatile constituents such as iridodials, dolichodials, and related compounds were assumed to retard the evaporation of the more volatile repellent constituents (18,20) or to act as viscous defensive agents (20)(21)(22). However, to date, the possible functions of the pygidial gland chemicals of L. humile have been largely ignored, because L. humile workers do not display alarm reactions to crushed workers (19,23).…”

“…Furthermore, iridodials and iridomyrmecin in the pygidial gland secretion of Tapinoma sp. ants suppress aggression by other ant species when individuals are daubed with the secretion (22). Iridomyrmecin is also known to have an insecticidal knockdown effect (25).…”

Communication in the migratory termite-hunting ant Pachycondyla (= Termitopone) marginata (Formicidae, Ponerinae)

“…We also identified actinidine in the pygidial gland secretions, but could not determine any behavior modifying function of this substance in P. marginata. Actinidine also occurs in the pygidial gland secretions of the termite hunting ponerine species Megaponera foetens, where it elicits alarm reactions (Janssen et al in press), and in several dolichoderine species it may function as a repellent substance (Wheeler et al 1977;Tomalski et al 1987).…”

Gastral exocrine products of a myrmicine ant strongly overlap pygidial gland products of Dolichoderinae

“…Approximately 79 % of the volatile compounds were accounted for by a 3:1 mixture of iridodials (as six peaks) (A) and actinidine (B) (Cavill et al, 1976;Tomalski et al, 1987;Wuest et al, 1977), and a further 7-8 % by isomers of two lactones related to two iridodials: dihydronepetalactone (C) and iridomyrmecin (D) (NIST/EPA/NIH, 1999 ) (Fig. 1).…”

“…1). Actinidine (B) was identifi ed from its mass spectrum and direct comparison with a synthetic sample (Tomalski et al, 1987;NIST/EPA/NIH, 1999;Wuest et al, 1977). Iridodial (A) has four stereocenters, two of which are enolizeable, raising the possibility of eight diastereomeric dialdehydes.…”