Thepbodee Sumpan’s scientific contributions

The success of aquatic invasive species such as golden apple snails may be due to the fact that they are very adaptive and can live in wide range of environmental conditions. In contrast, native fauna such as Thai apple snails, which are less locally adaptive than exotic species, are gradually disappearing from their native ecosystems. This study investigated the environmental conditions in a habitat of golden apple snails (Pomacea canaliculata) and compared them with that of Thai native snails (Pila scutata). We also determined degrees of tolerance and growth rates between P. canaliculata and P. scutata raised in water of different qualities. The results revealed that in natural habitats of P. canaliculata, the water quality (dissolved oxygen (DO) 2.37 ± 0.04 mg l-1, (biological oxygen demand (BOD5) 10.40 ± 0.18 mg l-1) was much poorer than that of P. scutata (DO 8.03 ± 0.01 mg l-1, BOD5 0.83 ± 0.01 mg l-1). Furthermore, when the two types of snails were raised in water of different qualities in the laboratory (clean (DO7.79 ± 0.03 mg l-1, BOD5 1.15 ± 0.01 mg l-1), moderately deteriorated (DO2.30 ± 0.07 mg l-1, BOD5 12.08 ± 9.80 mg l-1) and deteriorated (DO 1.61 ± 0.03 mg l-1, BOD5 16.75 ± 6.51 mg l-1), P. canaliculata consumed larger quantities of food than P. scutata. We observed no statistically significant difference between the growth rates of P. canaliculata and P. scutata in clean water. In contrast, in moderately deteriorated and deteriorated water, growth rates of P. canaliculata were significantly higher than those of P. scutata, thus implying that deteriorated water negatively influenced P. scutata whilst having no adverse effects on P. canaliculata. In addition, in deteriorated water, while P. canaliculata survived throughout the eight weeks of the experiment, all P. scutata had died by the end of week five. Our results show that P. canaliculata was more tolerant to different environmental conditions than P. scutata, therefore, making them a very successful invader.

The aims of this study were to compare food consumption, growth rates, time to reach food, and food preferences of the golden apple snail (Pomacea canaliculata) and the Thai native snail (Pila scutata). The eggs of the two species collected from natural habitats were hatched in the laboratory. Snails of one month were raised together and separately to determine growth rates and food consumption. It was found that the growth rate of P. canaliculata was significantly faster than that of P. scutata when both were raised together and when they were raised separately. Both snails grew better when raised separately. P. canaliculata consumed significantly more food than P. scutata. When raised separately, P. canaliculata crawled to food at a significantly faster rate than P. scutata. On average, P. canaliculata and P. scutata took 8.2±3.2 and 15.1±3.1 min, respectively, to reach the food offered. To test for food preferences, four local species of aquatic plants, namely Hydrilla verticillata, Nymphaea lotus, Salvinia cucullata, and Alternanthera triandra were provided to both snails. It was discovered that P. canaliculata consumed all the four different food species offered. In contrast, P. scutata tended to feed on S. cucullata rather than the other species. It is concluded that P. canaliculata was superior to P. scutata in terms of growth rates, food consumption, and was also non-selective for food and therefore there is no doubt that in a shared habitat, P. canaliculata will influence P. scutata.