Alkaloid secretion inhibited by antibiotics in Aphaenogaster ants

Abstract Although alkaloids are frequent in the poison glands of ants of the genus Aphaenogaster , this is not the case for A. iberica . Hypothesizing that in the genus Aphaenogaster , alkaloids are produced by symbiotic bacteria, except for A. iberica , we treated an experimental lot of both A. iberica and a ‘classical’ Aphaenogaster species, A. senilis , with an antibiotic. Compared to workers from a control lot, this treatment reduced considerably alkaloid production in A. senilis , whereas A. iberica did not react to the treatment. Furthermore, the treatment induced an increase in cuticular hydrocarbon quantities in A. senilis , but not in A. iberica . An analysis of the ant microbiota will be the next step to confirm our hypothesis.