ZHENGZHOU - It is hard to imagine that the tiny creatures wriggling in silkworm rearing rooms in Jingziguan, Henan province, are so important to both the local economy and national water security.

Sericulture, the breeding of silkworms to produce raw silk, has been much more profitable than agriculture for Jingziguan, a town in Nanyang city. It has also helped protect the local Danjiang River, as mulberry bushes, which produce the leaves that silkworms eat, have strong roots that prevent soil erosion.

The water quality of the Danjiang is crucial as it forms a major part of China's south-north water diversion project, developed to irrigate the more arid upper half of the country. The central government has been ramping up a campaign to protect the project, with the State Council announcing cash rewards for water pollution whistleblowers late last month.

At the same time, Nanyang is facing a battle to ensure sericulture survives and prospers. As well as a rise in viruses affecting the mulberry bushes and silkworms, sericulturists are also worried about their children's preference for migrant labor over work in their family business.

Nanyang's success in fending off the viruses and keeping the next generation of sericulturists at home is of huge significance both in Henan and further afield.

Jingziguan used to be one of the most impoverished towns in Henan. Things improved from 1987, when Lu Xifang, a late sericulturist from Jiangsu Province, came to the town and encouraged locals to give it a try.

According to Nie Fuyan, a sericulturist in Zhangxiang Village of Jingziguan, the average yearly income of the villagers rose six-fold as they started rearing silkworms and selling their cocoons.

"The town's muddy riverside areas were perfect for growing mulberry bushes for silkworms to live on," Nie said.

"The root system of a mulberry tree is complex yet stable, which effectively prevents soil erosion. Their large leaves also adsorb dust," explained Duan Zhenlan, chair of the Shengkun Agriculture Corporation (SAC), established by Lu in 2012 to industrialize local sericulture.

"The green economy has remained one of our principles," Duan said. "The water has been cleaner since we took over nearly 8,000 acres of riverside land to plant mulberry trees."

Nie understands the departure of younger people from Jingziguan. "They've been in this small town for too long, so it's normal for them to want to leave for a while to see what it's like elsewhere," he said.

Other long-time sericulturists are confident the migrant laborers will return.

"All of us who have mastered the skills to raise silkworms will be able to pass on the torch very soon," believes Cheng Kangwa, a sericulturist in Jingziguan for more than 30 years. "Our children will eventually come back to pick up sericulture in their middle age."

Duan Zhenlan said the SAC will continue to strengthen industry chains to make businesses sustainable.

"While silkworms will be taken care of as usual, we'll try to make the most of the mulberry trees," she said. "With the green economy in mind, we hope to attract more young people and keep hold of them."