The population dynamics of Pomacea canaliculata (Lamarck, 1822) in relation to rice cultivation practice and seasons in Nakhon Pathom, Thailand

The objective of this research is to determine the dynamics of the golden apple snail (Pomacea canaliculata) population in two paddy fields of Nakhon Pathom Province. To study snail density, snails at each paddy field was randomly sampled consecutively by twenty 1x1 m-quadrats every two weeks for10 months from July 2005 to April 2006. The results showed that snail population highly fluctuated and depended on rice cultivation phases, field flooding, Asian openbill (Anastomus oscitans) predation, and probably molluscicide application. The harvesting and field preparation processes showed effective control on snail population. However, seasons and rainfall probably did not much affect the snail population growth because water level in the fields was well controlled by farmers during rice cultivation. Snail population could keep growing as long as the water was present in the field. In summary, the snail population settledin the fields was derived from field flooding from irrigation canals that served as adult snail reservoirs. Stork feeding, water regime in the paddy fields, and harvesting and field preparation practices depressed the snail population in paddy fields. Asian openbill appears to be a good biological control agent for this golden apple snail.