In collaboration with scientists from 18 countries, a research team from Shanghai-based East China University of Science and Technology has confirmed the benefits of the ancient rice-fish co-culture farming method, offering a scientific pathway for ecological agriculture and food security.

Their study validated that the traditional practice not only boosts rice yields, but also controls pests and diseases through ecological regulation. Rice yields in rice-fish co-culture systems increased by an average of 12.5 percent compared with traditional rice monoculture, according to their global data analysis.

Notably, the presence of fish nearly doubled the number of invertebrate predators and parasitoids in the fields, while pests decreased by 24.1 percent, diseases by 38.8 percent and weeds by 45.7 percent.

"Such research results provide a scalable solution with high ecological and production benefits to address global challenges such as food security, pesticide reduction, agricultural non-point source pollution and biodiversity loss," said Wan Nianfeng, a lead scientist on the research team and a professor at the university's School of Pharmacy.

A paper on the research, conducted by Chinese researchers in collaboration with peers from countries including the United Kingdom, France, the United States, Switzerland and Spain, was published as a cover article in Current Biology, a Cell Press journal, on Monday.

The practice of integrating rice cultivation with fish farming dates back 2,000 years to the Han Dynasty (206 BC-AD 220), with archaeological evidence supporting its historical use.

The rice-fish co-culture system in Qingtian county of Lishui city, Zhejiang province, was the first in China to be designated as a Globally Important Agricultural Heritage System by the Food and Agriculture Organization of the United Nations in 2005.

The research team said it discovered how the rice-fish co-culture mechanism enhances production through pathway analysis. In the two-trophic-level relationship between rice and pests, the method directly suppresses harmful organisms to boost yields. In the three-trophic-level relationship among rice, pests and natural enemies, it increases the number of natural enemies to suppress pests, achieving indirect yield enhancement.

"Remarkably, this top-down control effect persists across organic and nonorganic systems and in both temperate and tropical regions, forming a clear ecological chain in which rice-fish co-culture promotes natural enemy populations, which suppress pests and ultimately enhance rice productivity," Wan said.

To further verify the global effect, the team conducted a four-year field experiment. The results showed that compared with rice monoculture areas, rice-fish co-culture areas had significantly fewer pests, while the number of predatory spiders increased.

The researchers also found that both the thousand-grain weight and overall yield of rice improved. Pathway analysis reconfirmed that rice-fish co-culture enhances natural enemy populations to suppress pests, achieving indirect yield enhancement.

Pot behavior experiments further clarified the mechanism. The research team observed that fish species such as crucian carp and red carp prefer feeding on pests like brown planthoppers, but do not prey on predatory spiders.

"It suggested that fish play the role of 'precision regulators' in rice fields, directly reducing pests while protecting and reinforcing the natural 'pest control army', thereby establishing an efficient cooperative network for pest control," Wan said.

zhouwenting@chinadaily.com.cn