SALT LAKE CITY, March 1, 2010 Like silkworm moths, butterflies and spiders, caddisfly larvae spin silk, but they do so underwater instead on dry land. Now, University of Utah researchers have discovered why the fly's silk is sticky when wet and how that may make it valuable as an adhesive tape during surgery.
"Silk from caddisfly larvae known to western fly fishermen as 'rock rollers' may be useful some day as a medical bioadhesive for sticking to wet tissues," says Russell Stewart, an associate professor of bioengineering and principal author of a new study of the fly silk's chemical and structural properties.
"I picture it as sort of a wet Band-Aid, maybe used internally in surgery like using a piece of tape to close an incision as opposed to sutures," he adds. "Gluing things together underwater is not easy. Have you ever tried to put a Band-Aid on in the shower? This insect has been doing this for 150 million to 200 million years."
The new study, funded by the National Science Foundation, is set for publication this week in Biomacromolecules, a journal of the American Chemical Society.
There are thousands of caddisfly species worldwide in an order of insects named Trichoptera that are related to Lepidoptera, the order that includes moths and butterflies that spin dry silk. Because caddisflies are eaten by trout, fly fishermen use caddisfly lures. Some species spend their larval stages developing underwater, and build an inch-long, tube-shaped case or shelter around themselves using sticky silk and grains of rock or sand. Other species use silk, small sticks and pieces of leaves.
Each larva has a head and four legs that stick out from the tube. The larval case often is conical because it gets wider as the larva grows. A caddisfly larva eventually pupates, sealing off the tube as it develops into an adult fly and then hatches.
Aquatic caddisflies and terrestrial butterfli
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University of Utah