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Pomacea insularum is a tropical and subtropical , ampullariid , freshwater prosobranch snail that is native to slow -flowing rivers and canals in South America . It is a member of the genus , Pomacea , and , like other species in this genus , can be a severe agricultural pest in wetland rice and taro agriculture systems . It has been introduced to the United States , establishing populations in the rice belt region of southeastern Texas . The resistance adaptations of P . insularum were investigated with respect to important physico -chemical parameters including temperature , salinity , pH , emersion , desiccation and progressive hypoxia in order to predict its potential distribution in North America , evaluate its threat to U .S . rice and taro crops and to develop environmentally acceptable non -chemical control and management strategies to prevent its further dispersal in North America . The research results indicated that the main factor likely to limit the macrogeographic distribution of P . insularum in North America was temperature based on its incipient tolerated temperature range of 15 .2° -36 .6°C . Its 15°C lower lethal limit will restrict its distribution to southern and western coastal regions and Florida in the United States . The tolerances of P . insularum to salinity , pH , emersion , desiccation and hypoxia elucidated in this study can be utilized to develop a risk assessment for this species' microgeographic distribution . Its tolerated salinity range was 0 -6 .8 which should prevent it from deeply invading estuarine habitats . Its tolerated pH range is 4 .0 -10 .5 , which spans that of most freshwater invertebrate and fish species . Its incipient emersion tolerance ranged from 70 days at 30°C and >95 % relative humidity (RH ) to >308 days at 20° -25°C and 75 % - >95 % RH . Its maximum desiccation tolerance was loss of 58 % of total corporal plus extracorporal water . It was a moderate regulator of oxygen consumption when subjected to progressive hypoxia , maintaining a normal oxygen uptake rate down to a critical Po2 of 80 -120 Torr depending on temperature . These results indicated that , within its tolerated temperature range , P . insularum , will be most successful in oxygenated , flowing -water habitats and could be controlled by periodic dewatering of natural or wetland aquatic habitats . |
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