Effects of Golden Apple Snail (GAS, Pomacea canaliculata) on Quality of Rice Field Water and Agricultural Waterway Water and GAS Weed Feeding Levels and Mortality

This study was conducted to investigate the effects of Pomacea canaliculata and Cipangopaludina chinensis on water quality in rice field water (RFW) and agricultural waterway water (AWW). This study was also conducted to better understand P. canaliculata weed feeding behavior and the efficacy of weed extracts in controlling P. canaliculata. As time increased, levels of pH decreased after the introduction of P. canaliculata regardless of whether they were introduced into RFW or AWW. In the case of water temperature, there was no difference regardless of when P. canaliculata and C. chinensis were introduced. Turbidity in RFW and AWW did not differ with the introduction of C. chinensis, but it increased after the introduction of P. canaliuculata. COD (Chemical oxygen demand) and BOD (Biological oxygen demand) increased by the introduction of P. canaliculata and C. chinensis, regardless of water type, and was higher in areas with P. canaliculata than in areas with C. chinensis. T-P (total phosphorus) increased by more than 5 times with the introduction of P. canaliculata and C. chinensis regardless water type, but T-N (total nitrogen) increased 3 to 6 times. In the September survey, the occurrence of P. canaliculata around P. canaliculata nurseries was higher than in the July survey, and in both September and July surveys, occurrence rates were higher around agricultural waterways than streams. Water quality indicators such as pH and EC in areas with high habitat density of P. canaliculata were similar to those in areas with low habitat density. Generally, P. canaliculata preferred feeding on broadleaf weeds compared to sedge and grass weeds. Most broadleaf weeds such as Eclipta prostrata, Abutilon theophrasti, and Portulaca oleracea were 100% eaten within 14 days regardless of the size of P. canaliculata. However, P. canaliculata only ate 1-20% of Persicaria lapathifolia in 14 days. In studies using treatments of 10,000 ppm of water and boiled water extract of P. lapathifolia leaves, P. canaliculata had a 100% mortality rate. Therefore, this result implies that P. canaliculata can be effectively controlled in organic agriculture by using P. lapathifolia extracts.