There's no question that an individual snail is better off without parasites. The most common of the 14 parasites is an unnamed trematode species that castrates its unlucky snail host. Like many parasites, this one has a complex life cycle, beginning when an unwitting snail eats a parasite egg. The egg hatches into a small baby worm that finds its way to the snail's gonad (even the asexual snails have this sex organ). There, the parasite multiplies and forms hundreds of small round cysts that take over the inside of the shell, leaving hardly any room for the snail itself.

The parasite's life doesn't end there, however. In order for the parasite to become an adult and reproduce, an infected snail must be eaten by a duck or some other bird. In the duck's gut, the parasite cysts hatch into adult worms. They mate, and the eggs are released in the duck's feces for the next unsuspecting snail.

This might seem like a tough passage for the parasites, but they're quite abundant despite such a circuitous life journey. In some New Zealand lakes, up to 50 percent of the snails are infected.

Is our invasive snail some sort of "super clone," resistant to all parasites and therefore a better all-around invader? Is being parasite-free enough of an advantage to become invasive in a new region? Or is some other factor responsible for the transplanted snail's success?

Whatever the answer to these questions, more and more people and agencies, including the U.S. Fish and Wildlife Service, the Idaho Department of Fish and Game, and the International Flyfishers Association, are interested in controlling snail populations. If we could find a parasite population capable of infecting the western U.S. clone, then we would know that the invader was not a completely resistant "super clone." Also, we could investigate the parasite as a way to lower the snail populations here.

But using parasites to contain snail populations opens up a whole new can of worms, so to speak. By importing a new living thing to control an invader, the solution might become another problem if it has unintended consequences. On the other hand, if the "controller" lowers the invader's numbers without harming anything else, then we could reduce the damage done by the snails. A lot of testing is needed to make sure biocontrol agents are both effective and safe before they are imported.

Meanwhile, none of these avenues of research-from studying why invasives are invasive to finding safe biocontrol agents-were going to be explored, if I couldn't get my snails past the Los Angeles airport USDA checkpoint.

So I stalled, pointing out that we had followed the USDA and CDC rules. I was met with blank stares. "How do I know these snails are what you say they are?" the man asked. He and his sidekick pushed forms in front of me that meant they would be confiscating my critters.

Luckily, I was able to delay long enough to call my advisor, who said the magic words that let my portable freezer, my cooler full of live snails, and me get home to Pullman. Apparently, his words carried more weight than my forms. Still, I have to applaud the tenacity of the USDA employees. After all, their efforts are part of our defense against ecological invaders.

Alison Emblidge Fromme '04 received her master's degree in zoology from WSU's School of Biological Sciences. She recently married and lives in the Bay Area.

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