Coinfections with multiple pathogens can result in complex within‐host dynamics affecting virulence and transmission. While multiple infections are intensively studied in solitary hosts, it is so far unresolved how social host interactions interfere with pathogen competition, and if this depends on coinfection diversity. We studied how the collective disease defences of ants – their social immunity – influence pathogen competition in coinfections of same or different fungal pathogen species. Social immunity reduced virulence for all pathogen combinations, but interfered with spore production only in different‐species coinfections. Here, it decreased overall pathogen sporulation success while increasing co‐sporulation on individual cadavers and maintaining a higher pathogen diversity at the community level. Mathematical modelling revealed that host sanitary care alone can modulate competitive outcomes between pathogens, giving advantage to fast‐germinating, thus less grooming‐sensitive ones. Host social interactions can hence modulate infection dynamics in coinfected group members, thereby altering pathogen communities at the host level and population level.
We thank Bernhardt Steinwender and Jorgen Eilenberg for the fungal strains, Xavier Espadaler, Mireia Diaz, Christiane Wanke, Lumi Viljakainen and the Social Immunity Team at IST Austria, for help with ant collection, and Wanda Gorecka and Gertraud Stift of the IST Austria Life Science Facility for technical support. We are thankful to Dieter Ebert for input at all stages of the project, Roger Mundry for statistical advice, Hinrich Schulenburg, Paul Schmid-Hempel, Yuko Ulrich and Joachim Kurtz for project discussion, Bor Kavcic for advice on growth curves, Marcus Roper for advice on modelling work and comments on the manuscript, as well as Marjon de Vos, Weini Huang and the Social Immunity Team for comments on the manuscript. This study was funded by the German Research Foundation (DFG) within the Priority Programme 1399 Host-parasite Coevolution (CR 118/3 to S.C.) and the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no 291734 (ISTFELLOW to B.M.).
Milutinovic B, Stock M, Grasse AV, Naderlinger E, Hilbe C, Cremer S. Social immunity modulates competition between coinfecting pathogens. Ecology Letters. 2020;23(3):565-574. doi:10.1111/ele.13458
Milutinovic, B., Stock, M., Grasse, A. V., Naderlinger, E., Hilbe, C., & Cremer, S. (2020). Social immunity modulates competition between coinfecting pathogens. Ecology Letters. Wiley. https://doi.org/10.1111/ele.13458
Milutinovic, Barbara, Miriam Stock, Anna V Grasse, Elisabeth Naderlinger, Christian Hilbe, and Sylvia Cremer. “Social Immunity Modulates Competition between Coinfecting Pathogens.” Ecology Letters. Wiley, 2020. https://doi.org/10.1111/ele.13458.
B. Milutinovic, M. Stock, A. V. Grasse, E. Naderlinger, C. Hilbe, and S. Cremer, “Social immunity modulates competition between coinfecting pathogens,” Ecology Letters, vol. 23, no. 3. Wiley, pp. 565–574, 2020.
Milutinovic B, Stock M, Grasse AV, Naderlinger E, Hilbe C, Cremer S. 2020. Social immunity modulates competition between coinfecting pathogens. Ecology Letters. 23(3), 565–574.
Milutinovic, Barbara, et al. “Social Immunity Modulates Competition between Coinfecting Pathogens.” Ecology Letters, vol. 23, no. 3, Wiley, 2020, pp. 565–74, doi:10.1111/ele.13458.
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