African black slug serves as healthy reminder

New, invasive species can hide among imported plants, fruits, vegetables

WESLACO  –  A new, invasive species of slug found recently in South Texas serves as a good reminder to thoroughly wash fruits and vegetables before eating them, according to an expert with the Texas A&M AgriLife Extension Service.

Dr. Raul Villanueva, an AgriLife Extension entomologist in Weslaco, examines an African black slug, an invasive species found recently in Harlingen. (AgriLife Communications photo by Rod Santa Ana)

Dr. Raul Villanueva, an AgriLife Extension entomologist, examines an African black slug. (AgriLife Communications photo by Rod Santa Ana)

Several specimens found in March in a new residential area of Harlingen have since been identified as African black slugs, said Dr. Raul Villanueva, an entomologist at the Texas A&M AgriLife Research and Extension Center at Weslaco.

They were identified by mollusk specialists at a laboratory of the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service in Beltsville, Md., he said.

“The African black slug originated in Africa and is now endemic to Asia and several islands in the Caribbean,” Villanueva said. “How it got here is anybody’s guess. It could have come in on imported plants, turf, produce —  who knows? It hides very well among all those products.”

This is only the second find ever of the African black slug in the U. S., Villanueva said. The first find, also in the Lower Rio Grande Valley, occurred in the 1980s, but was eradicated with chemical pesticide baits called molluscicides.

“Fortunately, we have never found the nematode that can be carried by the African black slug,” he said. “These nematodes, or tiny worms, pose serious health risks to humans, including meningitis. But the nematode has never been detected here. Nevertheless, it’s a good idea to thoroughly wash fruits and vegetables before consuming them.”

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The African black slug is a slimy, black mollusk about an inch long with a distinctive white mark on its back, unlike several harmless species of black slugs native to the Lower Rio Grande Valley that are solid black.

The African black slug is endemic to Asia and the Caribbean. It was recently found in Harligen and is considered an invasive species. (AgriLife Extension photo by Rod Santa Ana)

The African black slug is endemic to Asia and the Caribbean. It was recently found in Harligen and is considered an invasive species. (AgriLife Extension photo by Rod Santa Ana)

“So far, there have been only a few of these African black slugs found in one localized urban area of Harlingen,” Villanueva said. “Others have been found nearby, but they are very slow movers, so it’s not likely they will spread.”

Residents of the area in Harlingen where they were found have been advised to treat their lawns and not handle slugs if they find one, he said. Should anybody touch one, they are advised to wash their hands. If they must be handled, wear gloves or us forceps.

African black slugs feed on plants at night to avoid the heat of the sun, which can quickly dry them out, Villanueva said.

“They require high humidity and moist areas to reproduce and thrive, so our Valley weather is not their ideal habitat. It’s highly unlikely they will survive here, but as always, it’s important that people wash fruits and vegetables to avoid pathogens of all kinds.”

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