Biodiversity and the Natural Suppression of Human Pathogens

Restoring livestock to mixed-vegetable farms allows on-farm fertilizer production and the sale of high-value meat products.  Likewise, diversifying farms with native plants provides habitat for pest-killing birds and predatory insects. Unfortunately, both practices carry the risk of unintentional contamination of produce by human pathogens (e.g., E. coli O157:H7), transmitted through livestock feces or those of vertebrate wildlife drawn to native plantings. Currently, the only way to manage this risk is to remove all natural vegetation from the farm, which disrupts natural pest control, or to install deer-fencing around the entire farm perimeter, which is expensive and cannot exclude all vertebrate carriers of human pathogens. Arthropods and microbes that eat feces likely reduce this risk, but little is known about coprophage biodiversity, impacts, or conservation. Working on farms varying in their levels of livestock integration, we propose to: (1) Quantify biodiversity of feces-feeding arthropods (e.g., dung beetles, flies) through intensive field sampling; (2) Assess functional-genetic diversity of soil microbes using next-generation sequencing approaches, focusing on genes likely to be active in feces digestion; and (3) Relate biodiversity among coprophagous arthropods and microbes to rates of feces removal and E. coli suppression. Our ultimate goal is to provide vegetable growers with practical ways to reduce the risk of harboring human pathogens on their farms, by conserving and augmenting beneficial coprophagous insects and microbes. We address BIOAg goals by developing “biologically-intensive approaches to sustainable management of soil quality, whole farm food systems, livestock and animal health, and organic wastes.”