Rice rodents make millions in Asia hungry

Eco-friendly ways to stop rats wreaking havoc form the new arsenal against 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.

The International Rice Research Institute (IRRI) here said rats make a meal of rice plants, strip unharvested grains, feast on harvested grains and contaminate it with their 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,” according to Dr. Grant Singleton, rodent expert at IRRI who added that rodent outbreaks across Asia’s rice farms are getting increasingly worse.

Around 100,000 farmers in the Mekong and Red River deltas of Vietnam and 75,000 rice farmers in Indonesia have adopted the approach resulting in less damage and higher production.

But IRRI said that smallholder farmers can work as a community, and adopt smart, green solutions to outwit this clever little adversary.

Dr. Singleton said ecologically-based rodent management (EBRM) has now taken center stage in Asia, Australia, and Eastern Africa for management of rats in agricultural systems, adding studies have proven that rat population can be controlled and successfully managed if farmers work together as a community and apply their control at the right time and in the right habitats.

He said that IRRI, in close collaboration with the Irrigated Rice Research Consortium (IRRC), helps communities develop and carry out ecologically sound and cost-effective management strategies against rats.

The IRRI-IRRC venture has led to a 50-percent reduction in the use of chemical rodenticides. If losses are high each year for a particular rice crop, then a strategy recently developed to supplement EBRM across much of Southeast Asia is the community trap barrier system, said Dr. Singleton.

“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,” he said.

Dr. Singleton said farmers are encouraged to work together as a community to 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, ” he said.

Dr. Singleton cited farmer Esmeraldo Joson, Jr., from Nueva Ecija, who after experiencing serious rat problems along with his whole community, adopted the “ecologically based rat management” approach, and now knows how to manage rats better, working with his community so there are fewer rats in their fields and rat damage is less.

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

According to IRRI, farmers may not only suffer yield losses through droughts, floods, typhoons, destructive insects, and diseases.

Farmers also can suffer high yield losses as well as postharvest losses because of rats. Occasional rodent outbreaks can lead to severe effects on the livelihoods of small farmers, IRRI said.

In non-outbreak years, annual pre-harvest losses due to rats can be as much as 17 percent. A six percent rice loss in Asia already translates to enough rice that can feed 230 million people, roughly the population of Indonesia for 12 months, it said.

IRRI said rats can do damage in almost every phase of farming from munching on seedlings to eating stored grain. They also bring diseases, citing the Chittagong Hill Tracts of Bangladesh where rats were reported feasting not only on stored sacks of grain but also invaded houses, destroyed personal possessions, and bit people while they slept. This increased dysentery incidences and fever of unknown causes among people. Although not clinically proven, the diseases were believed to have been caused by rats.

A book published by IRRI and co-edited by Dr. Singleton titled, “Rodent Outbreaks: Ecology and Impacts,” was 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.

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.

Dr. Singleton notes that not all rat species are pests. “On a continental scale, usually less than 10 percent 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, and at the same time helping smallholder farmers reduce the impact of pest species on their crops,” he said.

Dr. Singleton 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.” PNA

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