Treating cattle with antibiotics affects greenhouse gas emissions, and microbiota in dung and dung beetles

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 283; no. 1831; p. 20160150
• Main Authors: Hammer, Tobin J., Fierer, Noah, Hardwick, Bess, Simojoki, Asko, Slade, Eleanor, Taponen, Juhani, Viljanen, Heidi, Roslin, Tomas
• Format: Journal Article
• Language: English
• Published: England The Royal Society 25.05.2016
• Subjects: Air Pollutants - metabolism; Animals; Anti-Bacterial Agents - administration & dosage; Antimicrobial; Archaea; Biochemistry and Molecular Biology; Biokemi och molekylärbiologi; Body Size; Carbon Dioxide - metabolism; Cattle - metabolism; Coleoptera - genetics; Coleoptera - microbiology; Coleoptera - physiology; Ecology; Ekologi; Feces - chemistry; Feces - microbiology; Gases; Genetic Fitness; Greenhouse Effect; Greenhouse Gases; Insect; Methane; Methane - metabolism; Microbiome; Microbiota - drug effects; Nitrous Oxide - metabolism; Population Density; insect; methane; antimicrobial; greenhouse gases; microbiome
• ISSN: 0962-8452; 1471-2954; 1471-2954
• DOI: 10.1098/rspb.2016.0150

Antibiotics are routinely used to improve livestock health and growth. However, this practice may have unintended environmental impacts mediated by interactions among the wide range of micro- and macroorganisms found in agroecosystems. For example, antibiotics may alter microbial emissions of greenhouse gases by affecting livestock gut microbiota. Furthermore, antibiotics may affect the microbiota of non-target animals that rely on dung, such as dung beetles, and the ecosystem services they provide. To examine these interactions, we treated cattle with a commonly used broad-spectrum antibiotic and assessed downstream effects on microbiota in dung and dung beetles, greenhouse gas fluxes from dung, and beetle size, survival and reproduction. We found that antibiotic treatment restructured microbiota in dung beetles, which harboured a microbial community distinct from those in the dung they were consuming. The antibiotic effect on beetle microbiota was not associated with smaller size or lower numbers. Unexpectedly, antibiotic treatment raised methane fluxes from dung, possibly by altering the interactions between methanogenic archaea and bacteria in rumen and dung environments. Our findings that antibiotics restructure dung beetle microbiota and modify greenhouse gas emissions from dung indicate that antibiotic treatment may have unintended, cascading ecological effects that extend beyond the target animal.