Fire ants feed their nestmates with their own venom

Authors: Chen, Jian; Du, Yuzhe - Cathy

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2022
Publication Date: 8/12/2022
Citation: Chen, J., Du, Y. 2022. Fire ants feed their nestmates with their own venom. Journal of Insect Physiology. 142:104437. https://doi.org/10.1016/j.jinsphys.2022.104437.
DOI: https://doi.org/10.1016/j.jinsphys.2022.104437

Interpretive Summary: Ants are supposed to be vulnerable to infectious disease due to their intimate contacts among colony members and low genetic diversity. However, ants are very successful in controlling disease because they have evolved remarkable adaptations to overcome their vulnerability to the disease. It has been long known that ants use their own antibiotic venom as external disinfectants to prevent disease by incorporating the venom onto the nest material and the surface of their brood. ARS scientists found significant amount of venom alkaloids in the crops and midguts of red imported fire ants, indicating fire ants also use their venom as an internal antibiotic. This discovery is important not only to our understanding in ant social immunity, but also to the future implementation of biological control of fire ants using pathogenic microorganisms.

Technical Abstract: Infectious disease is a great challenge to social insects. Remarkable adaptations have been evolved in social insects to combat epidemics. Venom secretion is widely used by ants for disease control, which is generally used as an external disinfectant. Here we report evidence that Solenopsis invicta use their own venom as an internal medication. Venom alkaloids at concentration levels that were reported to be effective against various pathogens were found in crops and midguts of ants. Venom alkaloids were found in midguts of the larvae, indicating that trophallaxis must be involved in the transfer of venom, since larvae do not produce alkaloids and they depend on workers to be fed. The queen provided alkaloids to her first batch of larvae in the incipient colony. Collective utilization of venom as an internal antibiotic may play an important role in the social life of fire ants and their evolution.