Can dung beetles make organic food safer?
Dung beetles can help suppress E.coli in soil, say researchers
Source: Entomology Today
For farmers — especially organic farmers, who are increasingly challenged by food safety guidelines — dung beetles could provide an elegant solution to a vexing problem. Entomologists at Washington State University are investigating whether the insects could suppress harmful foodborne pathogens in the soil before they spread to humans.
The research will take place on 45 farms in Washington, Oregon and California, thanks to a $500,000 grant recently awarded by the US Department of Agriculture’s National Institute of Food and Agriculture Organic Research and Extension Initiative.
Dung beetles play an important role in removing faeces, which can contain E. coli bacteria, and in killing pathogens in the faeces.
“Organic farmers have so few options for reducing their risk of E. coli,” said Matt Jones, a doctoral student who will lead the three-year investigation. “They fund an awful lot of post-harvest work for food safety, but relatively less is being done right on the farm, trying to work with what eats poop and what eats E. coli. We’re trying to pay attention to the ecology of the pathogen. You can think of dung beetles as an ecologically based cleanup crew.”
Droppings left by wildlife, domestic animals, and birds that carry harmful E. coli bacteria can contaminate farm produce, putting consumers and farmers at risk for illness and lawsuits. Some farmers have pulled out windbreaks, drained ponds, and installed extensive fencing in order to decrease the risk of contamination from rodents, deer, and birds. These measures are expensive and not necessarily backed by scientific research to reduce risk, said Bill Snyder, WSU professor of entomology.
Simplifying the landscape in this way runs counter to the organic approach of increasing diversity on the farm in order to take advantage of natural ecosystem processes like pollination and pest control.
“We could be making the problem worse,” Snyder said. “By simplifying the environment, do you reduce the population of dung beetles?”
Different types of dung beetles have evolved diverse ways of eating, living in, and laying their eggs in animal faeces. Together these approaches provide a “blanket attack” on animal faeces.
Jones wants to understand the relationships between the beetles’ activities, farm management practices, and the natural suppression of human-pathogenic E. coli. He will collect data at organic, conventional, and integrated livestock/produce farms about the number of dung beetle species, how they are spread across different types of farms and how quickly they consume animal faeces.
In the lab, he’ll measure the survival rate of the particularly harmful O157:H7 E. coli bacteria in soils collected from the farms in the presence of the different species of dung beetles.
Most food safety guidelines, known as good agricultural practices or GAPs, focus on improving post-harvest handling practices.
The ultimate goal of this project is to provide new and long-time growers with tools to effectively improve the natural suppression of human pathogens on the farm — and to inform the debate on farm-based food safety practices with scientific research.
Jones said it’s too soon to know just what the potential management strategies might be, but the project includes extension components to make sure growers are informed. A series of farm-walk field days, called “Dirty jobs: Nature’s pooper scoopers and how they can help save your farm,” will be offered to teach growers how to monitor dung beetles on their farms.
Meanwhile, Jones has his work cut out for him.
“It’s a glamorous project,” Snyder joked. “Matt drives around to all these farms with a freezer full of pig poop for baiting dung beetle monitoring traps.”