[Comparative studies on the function of the metapleural gland in ants]

In 6 of 7 ant subfamilies investigated, the workers produce an acidic secretion in their metapleural glands. With the exception of the gland fluid of Cremastogaster (Physocrema) inflata, all tested secretions were found to suppress the growth of Escherichia coli. From this and from former results, it is concluded that the metapleural gland contents function as an antiseptic.In Cremastogaster inflata the metapleural gland is greatly enlarged. The workers release the highly sticky secretion when attacked and so immobilize their arthropod enemies. In addition the fluid releases alarm behavior; the antiseptic gland has become a defence-alarm gland.The acidic antibiotic secretion from the enlarged metapleural glands of Cremastogaster (Physocrema) difformis is not sticky. It is constantly discharging in small quantities protecting the colony against microorganisms. When workers fight against animal enemies, the discharge can be increased. Enemies are repelled by the irritating tar-like smell.