Could dung beetles boost food safety on the farm?

Food safety doesn’t start at the processing facility.

Farmers go to great lengths to protect their crops from invading pathogens. Recent years have seen outbreaks attributed to bacteria like E. coli deposited by passing wildlife (through their droppings) and runoff from nearby livestock feedlots, which can infect low-to-the-ground crops like broccoli and leafy greens. Though science is still figuring out how bacteria most often goes from soil to crops (through the roots? By getting on the surface?), it can be safely said that keeping pathogens from contaminating soil in the first place is the goal.

“Farmers are more and more concerned with food safety,” said Matthew Jones, who recently conducted research on the matter as part of his PhD project. “If someone gets sick from produce traced back to a particular farm it can be devastating for them.”

What if there was a natural way to help suppress E. coli and other pathogens in the field?

A team of researchers examined the potential effects of an unlikely hero, the dung beetle, on crop fields, looking at the way the beetles bury feces below the ground, where pathogens are less likely to survive. (Not all dung beetles roll those famous balls that quadruple their bodies in size — some bury feces in tunnels.)

Jones drove a van full of dung beetle bait — pig feces — along the U.S.’s West Coast, following the planting of broccoli at 70 farm fields. Some farms were organic, and some were conventional. Others also raised livestock.

“We found that organic farms generally fostered dung beetle species that removed the feces more rapidly than was seen on conventional farms,” said William Snyder, a professor at Washington State University who was involved with the study.

Jones and his team point out that previous research has suggested beetles have antibiotic-like compounds on their bodies. Though beetles aren’t infallible bacteria-killers, they might make it harder for pathogens to survive for this reason and because of the way they consume and bury feces.

Just how good a job do they do, though? The researchers exposed the three most common species they found in the fields to pig feces contaminated with E. coli. Onthophagus taurus beetles were found to reduce E. coli by more than 90%, and Onthophagus nuchicornis did so by about 50%.

The team also found evidence that organic farms are more likely to have biodiversity in terms of soil bacteria, which seemed to decrease the survival of pathogens as well.

So, while it’s unlikely that dung beetles will take over the food safety industry, it seems they do their part to help, as much as little bugs can, at least.

“Nature has a ‘clean-up crew’ of dung beetles and bacteria that quickly remove feces and pathogens within them, it appears,” Jones said. “So, it might be better to encourage these beneficial insects and microbes.”

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