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 from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.