Nav: Home

Food safety: Dung beetles and soil bacteria reduce risk of human pathogens

March 19, 2019

Food safety regulations increasingly pressure growers to remove hedgerows, ponds and other natural habitats from farms to keep out pathogen-carrying wildlife and livestock. Yet, this could come at the cost of biodiversity.

New research published today in the Journal of Applied Ecology encourages the presence of dung beetles and soil bacteria at farms as they naturally suppress E. coli and other harmful pathogens before spreading to humans.

Wild and domesticated pig faeces have been known to contaminate produce in the field, leading to foodborne illnesses. Wild, or feral, pigs especially pose a risk of moving around pathogens as farmers cannot control where or when these large animals might show up.

Matthew Jones, who led the research as part of his PhD project at Washington State University, said: "Farmers are more and more concerned with food safety. If someone gets sick from produce traced back to a particular farm it can be devastating for them."

"As a result, many remove natural habitats from their farm fields to discourage visits by livestock or wildlife, making the farmland less hospitable to pollinators and other beneficial insects or birds", he added.

Dung beetles bury faeces below ground and make it difficult for pathogens to survive. To study how this may aid food safety, the entomologist drove a van full of pig faeces along the US West Coast to follow the planting of broccoli at 70 farm fields during the growing season. Broccoli, much like leafy greens, is susceptible to faecal contamination due to its proximity to the ground and the likelihood of humans consuming it without cooking.

The pig faeces were used to attract dung beetles and see how quickly they would clean up. The experiment was carried out at conventional and organic farms, and farms with or without livestock.

The organic farms seemed to attract a diverse range of dung beetle species that were most effective at keeping foodborne pathogens at bay. At conventional fields or those surrounded by pastureland, a less effective and accidentally introduced species (Onthophagus nuchicornis) outweighed the number of native dung beetles.

"We found that organic farms generally fostered dung beetle species that removed the faeces more rapidly than was seen on conventional farms", said Professor William Snyder of Washington State University.

Dung beetles likely kill harmful bacteria when they consume and bury the faeces. Previous research also suggested that these beetles have antibiotic-like compounds on their body.

To validate these findings, the researchers exposed the three most common species found in the field survey to pig faeces contaminated with E. coli. A 7-day laboratory experiment revealed that Onthophagus taurus and Onthophagus nuchicornis, both of which bury faeces as part of their breeding behaviour, reduced E. coli numbers by > 90% and < 50% respectively.

They also found that organic farming encouraged higher biodiversity among soil bacteria, which decreased the survival of pathogens.

"Bacteria are known to poison and otherwise fight among themselves and the same may be happening here", said Snyder.

These results suggest dung beetles and soil bacteria may improve the natural suppression of human pathogens on farms, making a case for reduced insecticide use and the promotion of greater plant and insect diversity.

"Wildlife and livestock are often seen as something that endanger food safety, but our research shows that reducing on-farm biodiversity might be totally counterproductive", Jones concluded.

"Nature has a 'clean-up crew' of dung beetles and bacteria that quickly remove faeces and the pathogens within them, it appears. So, it might be better to encourage these beneficial insects and microbes."
-end-


British Ecological Society

Related Bacteria Articles:

Conducting shell for bacteria
Under anaerobic conditions, certain bacteria can produce electricity. This behavior can be exploited in microbial fuel cells, with a special focus on wastewater treatment schemes.
Controlling bacteria's necessary evil
Until now, scientists have only had a murky understanding of how these relationships arise.
Bacteria take a deadly risk to survive
Bacteria need mutations -- changes in their DNA code -- to survive under difficult circumstances.
How bacteria hunt other bacteria
A bacterial species that hunts other bacteria has attracted interest as a potential antibiotic, but exactly how this predator tracks down its prey has not been clear.
Chlamydia: How bacteria take over control
To survive in human cells, chlamydiae have a lot of tricks in store.
Stress may protect -- at least in bacteria
Antibiotics harm bacteria and stress them. Trimethoprim, an antibiotic, inhibits the growth of the bacterium Escherichia coli and induces a stress response.
'Pulling' bacteria out of blood
Magnets instead of antibiotics could provide a possible new treatment method for blood infection.
New findings detail how beneficial bacteria in the nose suppress pathogenic bacteria
Staphylococcus aureus is a common colonizer of the human body.
Understanding your bacteria
New insight into bacterial cell division could lead to advancements in the fight against harmful bacteria.
Bacteria are individualists
Cells respond differently to lack of nutrients.

Related Bacteria Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Changing The World
What does it take to change the world for the better? This hour, TED speakers explore ideas on activism—what motivates it, why it matters, and how each of us can make a difference. Guests include civil rights activist Ruby Sales, labor leader and civil rights activist Dolores Huerta, author Jeremy Heimans, "craftivist" Sarah Corbett, and designer and futurist Angela Oguntala.
Now Playing: Science for the People

#521 The Curious Life of Krill
Krill may be one of the most abundant forms of life on our planet... but it turns out we don't know that much about them. For a create that underpins a massive ocean ecosystem and lives in our oceans in massive numbers, they're surprisingly difficult to study. We sit down and shine some light on these underappreciated crustaceans with Stephen Nicol, Adjunct Professor at the University of Tasmania, Scientific Advisor to the Association of Responsible Krill Harvesting Companies, and author of the book "The Curious Life of Krill: A Conservation Story from the Bottom of the World".