Ecological Risk Screening Summary - Giant Applesnail (Pomacea maculata) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally, and a high or medium climate match to the contiguous United States.

Pomacea maculata, Giant Applesnail, is an aquatic snail species that is native to the La Plata and Amazon basins in Argentina, Paraguay, Uruguay and Brazil. It has been used in the aquaculture and aquarium industries, which has led to its introduction in Asia and the Southeastern United States. P. maculata is also established in Spain and New Zealand. This species has been commonly misidentified with a congener, Pomacea canaliculata, a similar species with an overlapping distribution range, but recent genetic work has clarified the distinctiveness of these two species. The genus Pomacea is regulated in Arizona, Georgia, Hawaii, Louisiana, North Carolina, and Texas, which results in this species being prohibited or requiring a license or permit to be obtained in these states. The U.S. Department of Agriculture has also placed federal regulations on the genus Pomacea. Peer-reviewed literature reports that P. maculata has become invasive in the United States and has negative impacts in some introduced locations. The species is damaging to crayfish aquaculture in the United States and to rice agriculture in Southeast Asia. In mesocosm experiments, P. maculata disrupts wetland plant communities, nutrient cycling, and other wetland ecosystem services. It decreases feeding efficiency of juvenile Snail Kites (Rostrhamus sociabilis plumbeus), a federally endangered bird species. It can transfer a deadly toxin to birds, potentially including the Snail Kite. P. maculata is also a host for Angiostrongylus cantonensis, a nematode parasite capable of infecting humans. Competition with P. maculata is associated with decreased growth rates of P. paludosa, the native Florida Applesnail. The climate matching analysis for the contiguous United States indicates establishment concern for this species, especially in areas close to where it is already established in the Southeast and in Arizona. The Certainty of Assessment for this ERSS is classified as High due to a large amount of reliable scientific information showing negative impacts of this species’ introduction. The Overall Risk Assessment Category for P. maculata in the contiguous United States is High.