To fight infectious diseases, host immune defenses are employed at multiple levels. Sanitary behavior, such as pathogen avoidance and removal, acts as a first line of defense to prevent infection  before activation of the physiological immune system. Insect societies have evolved a wide range of collective hygiene measures and intensive health care toward pathogen-exposed group members . One of the most common behaviors is allogrooming, in which nestmates remove infectious particles from the body surfaces of exposed individuals . Here we show that, in invasive garden ants, grooming of fungus-exposed brood is effective beyond the sheer mechanical removal of fungal conidiospores; it also includes chemical disinfection through the application of poison produced by the ants themselves. Formic acid is the main active component of the poison. It inhibits fungal growth of conidiospores remaining on the brood surface after grooming and also those collected in the mouth of the grooming ant. This dual function is achieved by uptake of the poison droplet into the mouth through acidopore self-grooming and subsequent application onto the infectious brood via brood grooming. This extraordinary behavior extends the current understanding of grooming and the establishment of social immunity in insect societies.
Funding for this project was obtained by the German Research Foundation (DFG, to S.C.) and the European Research Council (ERC, through an ERC-Starting Grant to S.C. and an Individual Marie Curie IEF fellowship to L.V.U.). We thank Jørgen Eilenberg, Bernhardt Steinwender, Miriam Stock, and Meghan L. Vyleta for the fungal strain and its characterization; Volker Witte for chemical information; Eva Sixt for ant drawings; and Robert Hauschild for help with image analysis. We further thank Martin Kaltenpoth, Michael Sixt, Jürgen Heinze, and Joachim Ruther for discussion and Daria Siekhaus, Sophie A.O. Armitage, and Leila Masri for comments on the manuscript.
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Tragust S, Mitteregger B, Barone V, Konrad M, Ugelvig LV, Cremer S. Ants disinfect fungus-exposed brood by oral uptake and spread of their poison. Current Biology. 2013;23(1):76-82. doi:10.1016/j.cub.2012.11.034
Tragust, S., Mitteregger, B., Barone, V., Konrad, M., Ugelvig, L. V., & Cremer, S. (2013). Ants disinfect fungus-exposed brood by oral uptake and spread of their poison. Current Biology. Cell Press. https://doi.org/10.1016/j.cub.2012.11.034
Tragust, Simon, Barbara Mitteregger, Vanessa Barone, Matthias Konrad, Line V Ugelvig, and Sylvia Cremer. “Ants Disinfect Fungus-Exposed Brood by Oral Uptake and Spread of Their Poison.” Current Biology. Cell Press, 2013. https://doi.org/10.1016/j.cub.2012.11.034.
S. Tragust, B. Mitteregger, V. Barone, M. Konrad, L. V. Ugelvig, and S. Cremer, “Ants disinfect fungus-exposed brood by oral uptake and spread of their poison,” Current Biology, vol. 23, no. 1. Cell Press, pp. 76–82, 2013.
Tragust S, Mitteregger B, Barone V, Konrad M, Ugelvig LV, Cremer S. 2013. Ants disinfect fungus-exposed brood by oral uptake and spread of their poison. Current Biology. 23(1), 76–82.
Tragust, Simon, et al. “Ants Disinfect Fungus-Exposed Brood by Oral Uptake and Spread of Their Poison.” Current Biology, vol. 23, no. 1, Cell Press, 2013, pp. 76–82, doi:10.1016/j.cub.2012.11.034.
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