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 U.S. Department of Agriculture’s National Institute of Food and Agriculture Organic Research and Extension Initiative.
“Every vegetable grower struggles with this issue regardless of management practices,” said Bill Snyder, WSU professor of entomology. “It’s a wide open area where there is a hunger for more information and not a lot of good information out there.”
Attacking E. coli
Dung beetles play an important role in removing feces above ground and in killing pathogens in the feces that they feed on.
“We’re trying to pay attention to the ecology of the pathogen,” said Matt Jones, a doctoral student who will lead the three-year investigation. “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, Snyder said.
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 feces. Together these approaches provide a “blanket attack” on animal feces.
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 feces.
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.
Food safety begins on the farm
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.”
In addition to Snyder and Jones, the project team includes Thomas Besser, WSU College of Veterinary Medicine; John Reganold, WSU Crop and Soil Sciences; Daisy Fu, WSU Entomology; and David Headrick, Cal Poly San Luis Obispo.
by Sylvia Kantor | Washington State University | College of Agricultural, Human & Natural Resource Sciences