On the metapleural gland of ants, reloaded

The metapleural gland (MG) is a complex glandular structure unique to ants, suggesting a critical role in the evolutionary success of ants. At the origin of ants 120-140 million years ago, the MG was likely present in all castes, including males, but MG loss occurred repeatedly in diverse ant lineages, particularly in males. Four functions of MG secretions have received empirical support for at least some ants: antimicrobial sanitation, chemical defense, recognition odor, and territorial marking. An untested hypothesis is that MGs may produce mating pheromones as a secondary function in addition to antibiotics (Hölldobler & Engel-Siegel 1984). Towards assessing this hypothesis, we began the first chemical analyses of male and queen MG secretions for any ant. We outline an integrated approach drawing on functional morphology, phylogenetic history, comparative behavior, and chemical ecology to elucidate the evolutionary origin and diversification of the MG of ants.

Hölldobler B., Engel-Siegel H. 1984. On the metapleural gland of ants. Psyche 91: 201-224.