IRRI: Outwit rats with smart, green solutions

LOS BANOS, Laguna– Eco-friendly ways to stop rats wreaking havoc form the new arsenal against these rodent pests that chomp through millions of tons of rice every year and contribute to the undernourishment of 570 million people in Asia and the Pacific.

Rats make a meal of rice plants, strip unharvested grains, feast on harvested grains and contaminate them with droppings, spread diseases, invade people’s homes, destroy personal possessions, and even bite people in their sleep.

“Over the past three years, major rat outbreaks have led to staggering impacts on the lives of poor farmers in Asia,” said Dr. Grant Singleton, rodent expert at the International Rice Research Institute (IRRI). “Moreover, rodent outbreaks across Asia’s rice farms are getting increasingly worse.”

A book published by IRRI and co-edited by Dr. Singleton, “Rodent Outbreaks: Ecology and Impacts”, is the first to document at a global scale the factors that lead to rat outbreaks, their impacts, and the successes and failures of management actions – particularly in developing countries.

Ecologically based rodent management is now established as the most effective, affordable, and sustainable solution to manage rats. Around 100,000 farmers in the Mekong and Red River deltas of Viet Nam and 75,000 rice farmers in Indonesia have adopted the approach resulting in less damage and higher production.

“Ecological based rodent management veers away from expensive, toxic, or environmentally damaging poisons that may kill farm animals, local biodiversity, and natural predators of rats, such as birds of prey, and put farmers and their families at personal risk,” said Dr. Singleton.

“Instead, farmers are encouraged to work together as a community,” he added. “They collect rats at key times and in source habitats, increase hygiene in rice fields and around villages, and plant crops within two weeks of each other at the village scale.”

“Doing so limits the rat breeding season, which is linked to the development and ripening of rice seeds.”

Farmer Esmeraldo Joson, Jr., from Nueva Ecija, Philippines who initially experienced serious rat problems along with his whole community has tried the approach and says, “I now know how to manage rats better, working with my community so there are fewer in our fields and rat damage is less.”

“In many instances, it is society’s acceptance of rat outbreaks that is our greatest challenge,” said Dr. Singleton.

“In some areas of the Philippines, farmers say they plant two rows of rice for the rats, one for the birds, and seven for their family. This need not be the case given the progress of our knowledge on factors causing rodent outbreaks,” he added.

Dr. Singleton notes that not all rat species are pests. “On a continental scale, usually less than 10% of rodent species cause substantial impacts,” he explained.

“This is why there is a need to balance the impact of rat management actions so they target pest species rather than non-pest species, while at the same time helping smallholder farmers reduce the impact of pest species on their crops.”

He also adds, “More young biologists need to be encouraged to enter the fascinating secret world of rats and work closely with farmers to help them in their struggle caused by rats.”

The book also explores rodent ecosystems in Australia, Europe, New Zealand, East Africa, and North America. And for those interested, there is handful of rat recipes from Asia and Africa for the preparation of rat culinary delights.

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