Biological control of golden apple snail, Pomacea canaliculata by Chinese soft-shelled turtle, Pelodiscus sinensis in the wild rice, Zizania latifolia field

the wild rice, zizania latifolia turcz, used to be one of the important aquatic vegetables cultivated in china. recently, the golden apple snail - gas (pomacea canaliculata (lamarck)) was found to be a major invasive pest attacking z. latifolia. to control efficiently gas, predation by the chinese soft-shelled turtles (pelodiscus sinensis) on gas was evaluated in laboratory and field trials. p. sinensis had a strong predatory capacity and selectivity for gas both in laboratory and field conditions. all the sizes of p. sinensis prefer to capture smaller snails. the optimum number of p. sinensis released in z. latifolia field was dependent on the density of over-wintered gas, and varied between 30 and 50 turtles per 666.7 m2. the number of gas declined in the fields with turtles as compared to turtle-free field. a pattern of releasing p. sinensis in z. latifolia fields was developed and widely adopted by farmers because of much more benefit besides biologically controlling gas.