Metapleural glands (also called metasternal or metathoracic glands) are secretory glands that were considered unique to

ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

s and basal in the evolutionary history of ants. They are responsible for the production of an

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

fluid that then collects in a reservoir on the posterior of the ant's alitrunk. These reservoirs are also referred to as the bulla and vary in size between ant species and also between castes of the same species. As of 2023, research has found a metapleural gland convergently evolved in the wasp species '' Pelecinus polyturator''. From the bulla, ants can groom the secretion onto the surface of their

exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...

. This helps to prevent the growth of

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

and fungal spores on the ants and inside their nest. Though considered an important component in an ant's immunity against parasites, some ant species have lost the gland during their evolution. These losses correlate with ants that have a 'weaving' lifestyle, such as ants in the genus '' Oecophylla'', '' Camponotus'' and '' Polyrhachis''. It was originally suggested that because this weaving lifestyle also tended to involve an arboreal lifestyle, the parasite pressure above ground was not as great as for terrestrial ants, resulting in a reduced selective pressure to keep this antibiotic gland. Recent work suggests instead that these ants may just use other antiparasitic defenses such as increased grooming and venom. Most male ants are not known to have metapleural glands. It is believed that they benefit from the shared secretions of ant workers and do not need any themselves. Additionally,

slave-making ant Slave-making ants or slaver ants are brood parasites that capture Offspring, broods of other ant species to increase the worker force of their ant colony, colony. After emerging in the slave-maker nest, slave workers work as if they were in their ...

s do not have metapleural glands, though the slave species they use do and it is these ants that groom the slavemakers and their brood.

References

{{Reflist, 32em Insect anatomy Arthropod glands Myrmecology