Experience Influencing The Selection Of Predator, A Case Study With The Red Swamp Crayfish Procambarus Clarkii And The Gold Apple Snail Pomacea Canaliculata

The introduction of non-native plants, animals and pathogens is currently the most seriouse environmental threat globally. The colonization of invasive species in new territory might cause notorious impact to the invaded ecosystem, so do to local species.I used two invasive species, namely the red swamp crayfish Procambarus clarkii (from Nanjing) and the golden apple snail Pomacea canaliculata (from Hainan) as the predatory-prey pair to study when this two lineages of invasive species which never encounter each other before were brought together, what will happen. To test the hypotheses that the predation will be influenced by the size of prey, or influenced by encounter rate, I designed the experience where the prey were composed of three size-rank (small-sized, middle-sized and large-sized). Two experiments respectively examined one with prey consisted of three size groups with the same biomass, another with prey consisted of three size groups with the same individual numbers. The second part of the experiments is to test the hypothesis that experience of the predator will influence its subsequent predation. The results of the present studies are,(1) Subadult crayfish have the tendency of predating GAS of small sizes.(2) In the same biomass where small-sized snails are much more than middle-sized and large-sized snails in number PC always consumed small-sized GAS. In same-snail-number experiments, encounter rate were relatively enhanced, therefore PC consumed GAS prey other than of small-sized.(3) The crayfish with the experience of GAS consumption showed a more efficient predation rate, in comparision to the crayfish without such experience.The results showed that the small size of crayfish tend to feed Golden apple snail , so in the early invasive stage introduction the non-native predator can be achieved more satisfactory effective control results. Use of the two invasive species as predator and prey, not only for the purpose of consideration of control, and the study of the predatory behavior of two invasive species has important significance.