Slugs, Snails and Researchers Thrive in Wet Summer

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(Host) This summer’s cool wet weather may not be to the liking of many of us, but one Vermonter is finding it helpful in her work. That’s because the weather has produced a bumper crop of slugs and snails.

VPR’s Steve Zind explains.

(Bonnie MacCulloch) “Lots and lots of slugs…”

(Zind) Bonnie MacCulloch crouches on the lawn outside her office at the state complex in Waterbury and turns over a large rock. On the damp ground underneath there’s a glistening mass of small slugs. MacCulloch picks up a few and they begin to stir, their antennae bob gently as they slide along her gloved palm.

(MacCulloch) “Give it 30 seconds to wow you and you’ll have a whole different perspective on what these things are doing out there.”

(Zind) MacCulloch’s job with the Agency of Agriculture is to keep tabs on invasive species of plants, insects and animals in Vermont. To do that, she has to first know what’s already here.

Until now, no one has catalogued the state’s mollusks. MacCulloch has been cataloguing the mollusks in the Zadock Thompson Collection at the University of Vermont. Some of the specimens were collected a century ago. So this summer she is in the field to find out which snails and slugs are still present in Vermont.

MacCulloch says while mollusks aren’t at the top of the list of invasive species to be concerned about, they do represent a risk to agriculture and human health. Fist-sized Giant African snails are considered one of the world’s worst invasive species. In the 1960s, three of the snails multiplied to nearly 20,000 and destroyed crops in Florida. It’s the kind of problem MacCulloch would like to prevent in Vermont.

She says slugs and snails can reproduce quickly. They may not be built for speed, but they get around.

(MacCulloch) “They come over on cargo ships. They can come over on the wheels of planes.”

(Zind) MacCulloch says some foreign species are known to carry nematode parasites that present a serious health threat to humans. If a species carrying the nematodes found its way to Vermont, it could transfer the parasites to native slugs and snails which would also act as carriers.

(MacCulloch) “Because of the global movement of these species and the fact that over the last ten years so many new species have come into this country, it may be a matter of time before we start to recognize that some of these slugs can act as vectors and be a serious human health concern.”

(Zind)Slugs are more evolved than snails, and they have perhaps the most advanced sensory system of any invertebrate. They’re equipped with nerves that inspect the ground as they move and eyes that examine their surroundings. Slugs and snails are hermaphroditic; they don’t need mates to reproduce. But to maintain genetic diversity they exchange DNA. MacCulloch says some species of slugs, including species found in Vermont have been observed hanging from trees to accomplish this.

(MacCulloch) “Because their bodies are so muscular they can hang down almost three feet. A small slug that you would see that may be only two or three inches long can extend its body out almost three feet. They do this dance like ritual where they wrap around each other and in the process of doing that, they exchange mucous which transfers DNA from one organism to the other. So I think that’s pretty cool!”

(Zind) MacCulloch’s work is part of the federally funded North American Slug and Snail Survey. She says she welcomes the public’s help in collecting the samples. Anyone interested in providing specimens should contact Bonnie MacCulloch at the Agency of Agriculture.

For Vermont Public Radio, I’m Steve Zind.

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