CORVALLIS, Ore. — New research from Oregon State University Extension Service found that slugs and snails are strongly attracted to bread dough, a discovery that could lead to better control of these destructive pests in agriculture, nurseries and home gardens.
“We gave them a choice of food and they consistently went for the bread dough. They really, really like it. They went bonkers for it. Bread dough outperformed everything.”
Since ancient times, slugs have damaged crops. Today they cause billions of dollars in losses — including between $60 million and $100 million annually to Oregon’s grass seed industry alone, said Rory Mc Donnell, associate professor and Extension gastropod specialist.
“Damage to grass seed is a major issue,” Mc Donnell said. “But that’s just one crop. It’s mind boggling when you think about it. A huge array of crops is affected. They even take out specialty crops like mint. Many times, I’ve seen farmers lose an entire crop.”
Currently, nurseries, farmers and gardeners use baits containing metaldehyde, iron phosphate or sodium ferric EDTA to control slugs and snails. These products can be expensive, toxic to non-target species and vary in effectiveness, Mc Donnell said.
Bread dough, made from simple, inexpensive ingredients, could serve as an alternative — especially in developing countries where access to pesticides is limited. A dry formulation could have a long shelf life, be easy to ship and work by attracting slugs to traps or to baits containing molluscicides.
“Bread dough is a nontoxic, generic and effective tool that could be used in the detection and management of gastropods worldwide,” Mc Donnell said. “It represents a tool to aid in managing pest gastropod infestations, either using baited traps or in attract-and-kill approaches. It could also be incorporated into existing baits to improve their attractiveness.”
Trouble species in Oregon
Of the 28 exotic or non-native slug and snail species in Oregon, two are particularly damaging — European brown garden snails (Cornu aspersum) and gray field slugs (Deroceras reticulatum). These species plague nurseries and feed on hundreds of crops.
If European brown garden snails are found in shipments of Oregon nursery plants at out-of-state ports of entry, the plants must be treated or returned — both costly options.
“With worldwide trade and travel, we are getting a homogenization of slugs and snails on planet Earth because of the widespread introduction of species,” Mc Donnell said. “Slugs and snails have traveled with humans for thousands of years. But it’s getting more severe because of purposeful introductions, global trade, intensification of agriculture and development of new crops.”
Why bread dough works
The exact reason bread dough attracts slugs and snails remains unknown. Mc Donnell and his collaborators suspect the fermentation process is key. They tested bread dough against beer, cucumber, lettuce, strawberries, citrus, tomatoes, hostas and Marmite, a yeast-based spread popular in Great Britain.
“We gave them a choice of food and they consistently went for the bread dough,” Mc Donnell said. “They really, really like it. They went bonkers for it. Bread dough outperformed everything.”
In one trial, more than 18,000 snails were trapped within 48 hours. In Oregon field conditions, bread dough remained effective for at least eight days.
“It has something we call ‘good field life,’” Mc Donnell said. “If it worked for 12 hours, that would be good — but eight days gives a much bigger window for use.”
The project was a collaboration between Mc Donnell and his team; Robin Veasey and Jocelyn Millar, University of California at Riverside; Arnold Hara, University of Hawaii at Hilo; Amy Roda, U.S. Department of Agriculture (USDA), Miami; Gary Adams, USDA, Billings, Montana; and Ian Foley, Montana Department of Agriculture.
Funding came from the USDA under the Plant Protection Act Section 7721.
Previously titled Slugs and snails, destructors of crops and gardens, could be controlled by bread dough
