The Rice Water Weevil
A new rice pest in North Korea which attacks rice crops in the field
The Rice Water Weevil in Asia
Originally a native of North America, the rice water weevil was first found in the central area of Japan in 1976. By 1990, it had expanded its range into Korea, Taiwan ROC and mainland China.
In Japan, 50% of rice fields are still attacked by the pest, but it is being effectively controlled by the application of pesticide granules. Rice water weevils are common in both North Korea and Northern China, where they cause serious losses.
Control of the Weevil by Water Management
Research in Japan has found that draining rice fields in the middle of the rice season gives good control of the weevil. The more thorough the drainage, the fewer the number of larvae and cocoons per rice hill, and the higher the rice yield.
Recent field trials found that the thorough mid-season drainage of paddy fields is as good as chemical pesticides in controlling the weevil. The yield of milled rice from the plot given the drainage treatment was much the same as the yield from the plot with chemical control .
Life Cycle of the Weevil
Adult weevils eat the rice leaves, and lay their eggs inside the leaf sheaf below water level. When the larvae hatch, they go down into the roots and suck the root sap. It is at this time that most damage to the plant occurs. Larval damage reduces the number of new leaves produced by the plant. Heavily infested plants may wilt.
Acknowledgements
We are indebted to the Fukuoka Prefectural Agricultural Experiment Station of Japan, and to Dr. Kazuo Hirai of the National Agricultural Research Center, Japan, for the information in this article.
Index of Images
Figure 1 Adult Rice Water Weevil
Figure 2 Larvae of Rice Water Weevil in Roots of Rice Plant (Photo by Courtesy of Rda, Korea)
