Disclaimer:

The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: giant applesnail

Synonyms and Other Names: Ampullaria insularum, Ampullaria gigas, Pomacea insularum

Identification: Typical applesnails are globular in shape. Normal coloration typically includes bands of brown, black, and yellowish-tan, and color patterns are extremely variable. Albino and gold color variations exist (R. Howells, pers. comm.).

Size: Can reach 155 mm in shell height (Pain, 1960)

Native Range: Throughout much of tropical and subtropical South America (Hayes et al., 2012); Brazil (Amazon basin), Paraguay, Uruguay, and northern Argentina (Rio de la Plata basin) (Joshi et al. 2017).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: This large snail is found in freshwater lakes, rivers, streams, ponds and ditches, preferring slow-moving water. Applesnails are tropical to subtropical organisms and cannot survive below 50°F in the winter (Florida DOACS, 2002).

The sexes are separate and fertilization is internal (Andrews, 1964). Bright pink egg masses are laid on emergent vegetation or manmade structures above the water. They are held in place when the secreted mucous dries (Andrews, 1964). Individual eggs are very small, approximately 1-2 millimeter in diameter. An egg mass may contain over 2000 eggs (Barnes et al., 2008). May reach 6 inches in shell height and is considered the largest snail on earth (Florida DOACS, 2002).

The only terrestrial predator that has been observed capturing and eating apple snails is raccoon (Procyon lotor) (Carter et al. 2017).

The giant applesnail can tolerate a salinity of up to 8 PSU (practical salinity units;  Underwood et al., 2019).

Means of Introduction: Pomacea maculata is in the pet trade, and can be introduced by aquarium dumps (Florida DOACS, 2002). There is also evidence that the snail can be transported by flood waters (Advocate staff report 2018).

Status: Established in Florida, Georgia, Texas (Rawlings et al. 2007) and Louisiana, and most likely where there is evidence of egg masses, often first noticed prior to adults.

Impact of Introduction:

Summary of species impacts derived from literature review. Click on an icon to find out more...

Ecological

Applesnails are known agricultural pests, feeding on rice crops and causing great economic damage (Cowie, 2002; Hayes et al., 2008). This species has been known to be a carrier of the rat lungworm parasite in New Orleans and Mandeville, Louisiana populations, but it is not widespread in the applesnail population (J. Teem, pers. comm.).  Cattau et al. (2017) found that a predator of P. maculata, a snail kite (Rostrhamus sociabilis), has an increased bill size in response to the larger than normal prey size when compared to the native applesnail.

In 2018, an Acadia Parish, Louisiana, farmer shut down his crawfish harvest due to applesnails that had entered his rice fields when it was flooded with water from a bayou that flows into the Mermentau River (Advocate staff report 2018).

Remarks: Initially P. insularum had been identified as P. canaliculata in Florida, Georgia, and Texas. Genetic testing confirmed that specimens collected in Florida, Georgia, and Texas were P. insularum (Rawlings et al. 2007). Since then, P. insularum has been synonomized with P. maculata (Hayes et al., 2012).

Research by Savaya-Alkalay et al. (2018) suggests that the development of all-male prawn populations of Macrobrachium rosenbergii has the potential as a biocontrol agent over hatchling and adult apple snails (Pomacea spp.). Medium-sized and large prawns (10–30 g) efficiently preyed on snails up to 15mm in size, while small prawns (up to 4 g) effectively consumed snail hatchlings.

References: (click for full references)

Advocate staff report. 2018. Invasive snail found in Acadiana crawfish pond; pest also poses threat to rice plants. The Acadiana Advocate. Baton Rouge, LA. http://www.theadvocate.com/acadiana/news/article_a44e0de0-1039-11e8-ab97-efed1305c5da.html. Created on 02/12/2018. Accessed on 02/13/2018.

Andrews, E.B. 1964. The functional anatomy and histology of the reproductive system of some Pilid gastropod molluscs. Journal of Molluscan Studies 36(2):121-140.

Barnes, M.A., R.K. Fordham, R.L. Burks, and J.J. Hand. 2008. Fecundity of the exotic applesnail, Pomacea insularum. Journal of the North American Benthological Society 27(3):738-745.

Carter, J., S. Merino, D. Prejean, and G. LaFleur, Jr. 2017. Observations of raccoon (Procyon lotor) predation on the invasive Maculata apple snail (Pomacea maculata) in southern Louisiana. Southeastern Naturalist 16(3):N14-N18.

Cattau, C.E., R.J. Fletcher, Jr., R.T. Kimball, C.W. Miller, and W.M. Kitchens. 2017. Rapid morphological change of a top predator with invasion of a novel prey. Ecology and Evolution DOI:10.1038/s41559-017-0378-1, 10 pp.

Conner, L. Personal communication. Florida Fish and Wildlife Conservation Commission.

Cowie, R.H. 2002. Apple snails (Ampullariidae) as agricultural pests: their biology, impacts and management. Pages 145-192 in Barker, G.M., ed. Molluscs as Crop Pests. CABI Publishing, Wallingford, UK.

Denson, D. Personal communication. Florida Department of Environmental Protection.

Florida FDOACS. 2002. Applesnails. Technical Bulletin Number 3, 4 p. Accessed 6/28/2012 at http://edocs.dlis.state.fl.us/fldocs/doacs/aquaculture/techbull/2002no3.pdf

Grana, F. Personal communication. Puerto Rico Department of Natural and Environmental Resources.

Hayes, K.A., R.H. Cowie, S.C. Thiengo, and E.E. Strong. 2012. Comparing apples with apples: clarifying the identities of two highly invasive Neotropical Ampullaridae (Caenogastropoda). Zoological Journal of the Linnean Society 166(4):723-753.

Hayes, K.A., R.C. Joshi, S.C. Thiengo, and R.H. Cowie. 2008. Out of South America: multiple origins of non-native apple snails in Asia. Diversity and Distributions 14(4):701-712.

Howells, R. Personal communication. Texas Parks and Wildlife Department.

Howells, R. G. 2001. History and status of applesnail (Pomacea spp.) introductions in Texas. Texas Parks and Wildlife Department, Management Data Series No. 183.

Joshi R.C., Cowie R.H., and Sebastian L.S. (eds). 2017. Biology and management of invasive apple snails. Philippine Rice Research Institute (PhilRice), Maligaya, Science City of Muñoz, Nueva Ecija 3119.

Pain, T. 1960. Pomacea (Ampullariidae) of the Amazon River system. Journal of Conchology 24: 421-432.

Rawlings, T. A., K. A. Hayes, R. H. Cowie, and T. M. Collins. 2007. The identity, distribution, and impacts on non-native apple snails in the continental United States. BMC Evolutionary Biology, http://www.biomedcentral.com/1471-2148/7/97.

Savaya-Alkalay, A., Ovadia, O., Barki, A., and A. Sagi. 2018. Size-selective predation by all-male prawns: implications for sustainable biocontrol of snail invasions. Biological Invasions 20:137–149.

Shelton, D. Personal communication. Alabama Malacological Research Center.

Teem, J. Personal communication. Florida Dept. of Agriculture and Consumer Services.

Underwood, E.B., T.L. Darden, D.M. Knott, and P.R. Kinsley-Smith. 2019. "Determining the salinity tolerance of invasive island apple snail Pomacea maculata (Perry, 1810) hatchlings to assess the invasion probability in estuarine habitats in South Carolina, USA." Journal of Shellfish Research 38.1: 177-182.

Author: Benson, A.J.

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.