Chemical Come-on Created by AgBio Scientists Successfully Lures Love-sick Lady Lampreys to Traps

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Weiming Li (view larger image)

A synthetic version of the pheromone that male sea lampreys use to attract spawning females developed by an MAES scientist successfully lured females to traps and foiled the mating process of the destructive invasive species.

Pheromones, chemical scents used to attract a mate, are well-documented in the insect world. Weiming Li, MAES fisheries and wildlife scientist, has focused much of his career on the well-developed sense of smell of the sea lamprey. In 2002, after four years of painstaking research, Li and his team published results detailing their isolation and identification of the chemical that male lampreys use to lure females.

Li and doctoral student Nicholas Johnson, who did the research as part of his dissertation, and the rest of the team used the same exacting techniques to develop a synthetic version of the pheromone and test one of its components as a lamprey control. Tiny concentrations of the synthetic pheromone component, called 3kPZS, were as effective as the pheromone released by males in attracting females over hundreds of meters and wasn’t affected by habitat conditions.

“The pheromone is expensive to synthesize,” Li said, “but only a very small amount is needed for it to work successfully. It’s very potent. Only a few hundred grams, less than a pound, would be used each year.”

The research was published in the Jan. 19 issue of the Proceedings of the National Academy of Sciences.

By luring fertile females to traps baited with synthetic pheromone, fishery managers could prevent the females from mating and reduce lamprey populations. The synthetic pheromone also could be used to attract females for harvesting as a food fish. In France and Portugal, sea lamprey is considered an exquisite gastronomical delicacy.

“The Great Lakes Fisheries Commission would like to deploy one new integrated pest management control method by 2010 as a milestone for its sea lamprey management program,” Li explained. “The commission considers regulating spawning and migrating behavior with pheromones the most promising control method for implementation. So we’re excited about the possibilities.”

Currently, lampreys are controlled mainly by adding TFN, a compound that kills them in the larval stage, to freshwater streams where lampreys spawn. But there are environmental concerns about adding the chemical to streams, as well as the possibility that lampreys could develop resistance to TFN.

Sea lampreys, which resemble 18-inch-long eels, can live in both salt and fresh water and likely found their way into the Great Lakes via shipping channels. Because they’re an exotic invasive species, they have no natural predators in the Great Lakes. Lampreys are parasites—they stay alive by attaching themselves to other fish, such as salmon, trout and whitefish, and then sucking out the fish’s body fluids. The lamprey’s sucking disk and sharp teeth scar the host fish, and the experience kills many hosts.

In its parasitic stage, a sea lamprey can kill 40 or more pounds of fish. Lampreys are so destructive that, under some conditions, only one of seven fish attacked by a sea lamprey will survive. Lampreys caused the extinction of three species of whitefish in the Great Lakes. The U.S. and Canadian governments spend about $10 million to $15 million per year on lamprey control.

“It made sense for us to focus on the sea lamprey,” Li said. “It’s a poster animal for invasive species—very destructive, very expensive to control effectively.”

Besides Li and Johnson, other paper authors are Sang-Seon Yun, assistant professor; Henry T. Thompson, graduate student; and Cory Brant, graduate student, all in the MSU Department of Fisheries and Wildlife.

The research was supported by grants from the Great Lakes Fishery Commission and the National Science Foundation.

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