Farmers in Laos turn to game theory to try to outsmart the rats | Agricultural news

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For more than a decade, Laos has faced a growing rat problem as the rodents make their way through rice, the country’s main cash crop and staple food.

Described by farmers as a ‘sea of ​​rats’, the vermin eat away at least 20% of the country’s annual rice crop, putting further pressure on household finances and food security in what is already the one of the poorest countries in Southeast Asia. According to the United Nations World Food Programme, one in five Laotians was already food insecure even before the COVID-19 pandemic, while one in three children suffer from chronic malnutrition.

In wealthier countries, rodenticides like bromadiolone which prevent the blood from clotting are used to control rat and mouse infestations. But they also poison non-target species, soil, water and sometimes the farmers who apply them, and can be prohibitively expensive.

But a team of researchers from the National University of Laos and Australia’s Monash University have discovered a much simpler, cheaper and environmentally friendly solution that uses indigenous hunting tools and know-how. existing rodents: an economic game that pools the efforts of villagers and rewards those who kill or capture the most rats.

“If one farmer killed rats and the others didn’t, the rats would just continue to populate neighboring farms, but we knew we could get better results if they worked together,” said Paulo Santos, master of economics lectures at Monash University. . “The game was therefore designed to inspire collective action and designed as a pest control activity, the effectiveness of which depended on the decisions of others.”

More rice, more protein

Based on game theory – a branch of mathematics that examines strategies for dealing with competitive situations applied in fields as diverse as business and war – the concept was tested in 2018 and 2019 in 36 villages in the province of Luang Prabang, one of the most rat-affected areas in northern Laos.

Farmers and officials at a meeting on rat problems in Laos [Courtesy of Monash University]

“Rats are the pests that cause the most damage in Luang Prabang as they attack the entire agricultural production chain, from planting, to harvesting, to storage,” said Fue Yang, a researcher at the University. national of Laos who led the field team. who oversaw the trial. “Normally, farmers use a combination of pesticides, sticks and homemade traps inside which food is placed to attract rodents. But these methods have not been effective in reducing rodent populations.

Village farmers meet one day a month throughout the trial to eradicate rodents in a particular area. This mimics the behavior of killer whales and other wildlife that work together to isolate, fatigue and immobilize their prey, and builds on an old ‘red tail’ initiative in which NGOs paid hunters for each rat’s tail they found. they were producing.

Each member of the hunting party benefited from increased protein intake as rats are also a food source in Laos, while each farmer benefited from having more rice to eat or sell. But the most successful hunters in each village benefited even more by making a name for themselves in the community and receiving small cash prizes donated by the Australian Center for International Agricultural Research.

Published in PNAS, the journal of the National Academy of Sciences in Washington, DC, the trial produced 30% more rice than in previous seasons and 20% more rice than control villages. This added an average of 80 kg of unmilled rice per household per year, equivalent to two weeks’ supply of the key carbohydrate.

“The game showed that if farmers collectively contribute to rodent control, it benefits them in the long run,” says Fue.

A pile of rat tails brought in by villagers to show the number of rats killed
Villagers are usually paid to catch rats with money distributed based on the number of tails produced [Courtesy of Monash University]

Adds Kun Sesophon, director of Viengkham District Agriculture and Forestry Office in Luang Prabang: “Without this project, we would have suffered significant rice losses due to rodent damage.”

Playback of the game

The question now is whether the results can be sustained without the financial incentives provided by NGOs, and whether the approach can be replicated in other parts of Laos and the developing world.

Professor Silinthone Sacklokham, director of the SEAMEO Regional Center for Community Education Development in Laos, believes that the game is sustainable. “The rodent hunting contest is simple and inexpensive. It is simple and requires a low financial investment. We hope that in the future, the villagers will continue these rodent hunting activities,” she said.

But Chitpasong Kousonsavath, an agricultural economics educator at the National University of Laos who helped collect and collate the data collection for the trial in villages full of children with bloated bellies, says bureaucracy in Laos is likely to make it difficult to reproduce the test.

“Practically, I think it’s scalable and changeable in other provinces with rodent issues because money doesn’t have to be offered as a prize. Participants can be compensated with rice or other foodstuffs available in the local context so that it is not too difficult for other communities to adopt them,” she said. “But things are never simple in Laos. It took us a long time, over a year, just to get the permits for the trial. We started working on that in 2015.”

Kousonsavath also challenges assumptions made about the link between reduced rat populations and increased rice yields and food security.

“You cannot directly translate economic improvement into food security because the latter is quite complicated. Food security is influenced by many different variables such as consumption habits, cultural nuances and market linkages. And what is it exactly? Are we talking about the safety of carbohydrate intake? Protein safety? Or is it micronutrient security that is important for child development? »

Nonetheless, Monash University’s Santon believes the trial, believed to be the first of its kind in the world, is scalable in farming communities around the world and not just in rat control.

“This work is important because the game can be applied to any other region or any other problem that requires cooperation, such as water management, forest management, waste or garbage collection,” he said. he declares.

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