Managing the competition: How do burying beetles and microbes sustainably coexist in competition over shared resources?

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Antimicrobial resistance (AMR) is one of the most important public health issues that society currently faces. Inappropriate use of antibiotics has accelerated the rate at which bacteria have evolved resistance and the development of new antimicrobials is very expensive and time-consuming and has almost come to a halt. Consequently we need to develop better ways to sustainably utilize existing and future antimicrobials.However, there is a lack of consensus on the best way to manage resistance, especially for bacteria. Which resistance management strategy would be most effective? Is it most effective to reduce prescribing rates or should antimicrobials be given in combination, and if so, what combinations? It has been difficult to address these questions in a clinical setting and relevant experimental systems to validate resistance management strategies outside of clinical trials are currently rare. Here we proposal a novel approach to these problems: use organisms in which management of bacteria and other microbes is a fundamental part of their natural history to elucidate the most effective strategies to combat antimicrobial resistance. Burying beetles fit the bill perfectly. They process the carcasses of small vertebrates such as mice to rear their young and are unusual among invertebrates in having extended, complex parental care. In addition to feeding their offspring like birds do (burying beetle larvae beg to be fed and parents respond by regurgitating food - dead mouse) they also produce antimicrobial secretions to combat competition from microbes, especially bacteria. It is this latter form of parental care that we are most interested in here. Since there is evidence that burying beetles have been providing care and managing competition from microbes for approximately 100 million years there are likely to be substantial rewards from exploring what resistance management strategies they use.The particular novelty of our approach is to use experimental evolution to see how both beetles and bacteria respond to increased selection pressure from each other. We can therefore observe evolution in action and test the relative efficiency of different resistance management strategies directly. In particular we will challenge populations of burying beetles over successive generations with resistant bacteria that we will produce in the lab and see how they respond and what resistance management strategies they use. We predict that burying beetles reduce the rate at which bacterial communities evolve resistance by managing how different bacteria compete with one another through variation in the composition of the cocktail of antimicrobials that they produce. Our results are expected to provide a significant step forward in our understanding of how to manage AMR most effectively.