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Invasive Species Spotlight: Giant African Land Snail (Achatina fulica)

July 10, 2008

For the exotic pet collector, this giant snail may seem to be a unique and interesting specimen; land managers and farmers may disagree. As fascinating a creature as the giant African land snail is, it also is a threat to natural and agricultural areas.

Photo courtesy of www.invasive.org.

The giant African land snail (http://www.aphis.usda.gov/plant_health/plant_pest_info/gas/downloads/achatinafulica.pdf) is native to East Africa, mainly Kenya and Tanzania. It can now be found established throughout the northern half of Africa, southern Asia (including the numerous island and coastal countries), South America, Australia, and Hawaii. It was first found in the Hawaiian Islands in 1936 and remains there, it has also been reported in Arizona in 1959 and Florida in 1966 but was quickly eradicated.

Photo courtesy of www.invasive.org.

Though this giant snail is fairly large, it still travels at a snail’s pace. It has been found “hitchhiking” aboard shipping containers and plants from the Hawaiian Islands into the mainland United States, as well as smuggled in by international travelers for their interest as exotic pets. For the most part, quarantine authorities have been able to intercept this species and keep it from escaping, but they still routinely find them. To aid in control, it has been placed on the noxious pest list, making it illegal to transport, sell, or buy them anywhere in the United States.

The giant African land snail can be readily distinguished by its enormous size. An average size is around 3 in. tall and 8 in. long. Their shells form a conical shape that may coil in either direction, colored in several brown tones that vary slightly according to their diets. They are active at night and spend their days burrowed underground. Average snails can live up to 10 years in captivity but usually live around 3 to 5 in the wild. After their first year, they are able to copulate. Their rate of reproduction varies according to the quality of their habitat and climate. In Hong Kong, a clutch of eggs can number up to 300, while in Hawaii it can be as many as 1,000.

One of the difficult things about managing these snails is their ability to adapt to different conditions and diets. They are a threat to both natural and agricultural areas. Along with organic detritus, their preferred food list consists of over 500 known plants so far, ranging from coffee and bananas in the tropics to potatoes and tobacco in temperate areas.

Also of concern of the giant snails are several health issues. They may harbor and transmit the parasitic rat lungworm (Angiostrongylus cantonensis), which in turn can transmit eosinophilic meningoencephalitis to humans. A gram-negative bacterium, Aeromonas hydrophila, can also be transmitted to humans, leading to several problems, especially foor individuals with compromised immune systems.

Captured, and suspected populations of, sails should be reported to authorities in the U.S. Department of Agriculture. For more information, stop by the Illinois CAPS blog (www.illinoiscapsprogram.blogspot.com) for all the latest news on invasive pests in Illinois.

(Mike Garrett)

Author: Phil Nixon


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