- Author: Ben Faber
Food safety:
Dung beetles and soil bacteria reduce risk of human pathogens
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."
https://phys.org/news/2019-03-food-safety-dung-beetles-soil.html#jCp
Jones MS, Fu Z, Reganold JP, et al. Organic farming promotes biotic resistance to foodborne human pathogens. J Appl Ecol. 2019;00:1-11.
Read more at: https://phys.org/news/2019-03-food-safety-dung-beetles-soil.html#jCp
Read more at: https://phys.org/news/2019-03-food-safety-dung-beetles-soil.html#jCp
Read more at: https://phys.org/news/2019-03-food-safety-dung-beetles-soil.html#jCp
- Author: Ben Faber
CONTACT: Anita Brown (530) 792-5644
Assistance Available for California Producers to Aid Declining Monarch Butterfly
USDA Helps Producers Manage for Habitat, Improve Ag Operations
DAVIS, Calif., Jan. 28, 2019 – California agricultural producers can voluntarily help the monarch butterfly on their farms and ranches through a variety of conservation practices offered by the U.S. Department of Agriculture (USDA). This assistance comes at a critical time as recent reports show the western population of the monarch butterfly is at an all-time low.
“With the monarch butterfly's western population in peril, we're encouraging California producers to make simple tweaks on their farms that can go a long way for this iconic species,” said Carlos Suarez, state conservationist with USDA's Natural Resources Conservation Service (NRCS) in California. “NRCS offers more than three dozen conservation practices that enable producers to help monarchs and other pollinators as well as benefit their agricultural operations.”
The overwintering monarch butterfly's western population declined by 85 percent between 2017 and 2018, according to counts released by the Xerces Society for Invertebrate Conservation. Nationwide, the species has seen population declines since the 1980s, in part because of the decrease in native plants like milkweed – the sole source of food for monarch caterpillars.
As monarch butterflies migrate, they must have the right plants in bloom along their migration route to fuel their flight. Producers – especially those along California's coast and in the Central Valley and Sierra foothills – can play an important role in helping the species.
Through a variety of conservation practices, NRCS helps producers improve management of healthy stands of milkweed and high-value nectar plants and protect these stands from exposure to pesticides.
Planting native milkweeds is critically important to rebuild the western monarch population, but scientists at the Xerces Society recommend that milkweed not be planted within five miles of overwintering sites near the coast. It did not typically occur there and may prevent returning monarchs from going into their winter clusters.
NRCS also recommends California producers to establish plants that bloom in the fall, as monarchs head to coastal overwintering sites, and in the late winter and very early spring, as the winter clusters of monarchs break up. These fall-blooming species include goldenrod and asters, and late-winter species include coyote brush, manzanitas, and native California lilac and other Ceanothus species.
Read the complete news release online here.
-NRCS-