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MATING PHEROMONES IN LAMPREY SPECIES NATIVE TO THE GREAT LAKES
Nicholas Johnson╣, Tyler Buchinger▓, Yu-Wen Chung-Davidson3 and Weiming Li▓
╣USGS Hammond Bay Biological Station, 11188 Ray Road, Millersburg, MI 49759
▓Michigan State University, Department of Fisheries and Wildlife, Room 13 Natural Resources Building, East Lansing, MI 48824
Sea lamprey (Petromyzon marinus) use a male mating pheromone, partially comprised of 7α, 12 α, 24-trihydroxy- 3-one-5 α -cholan-24-sulfate (3kPZS). 3kPZS was recently registered by U.S. Environmental Protection Agency and Health Canada as a biopesticide to attract adult sea lamprey to traps as part of an integrated sea lamprey control program in the Great Lakes. However, the effects of 3kPZS on other lamprey species, including lampreys native to the Great Lakes, are unknown. Our goal was to determine if mating pheromones in lampreys are species-specific, with the specific objectives of determining if adult lampreys 1) biosynthesize 3kPZS, 2) release 3kPZS into the water, and 3) use mating pheromones consisting of 3kPZS. We found that (1) of 10 species tested, all had detectable concentrations of 3kPZS in liver and gill tissues, (2) of 11 species tested, only chestnut lamprey (Ichthyomyzon castaneus) released 3kPZS at rates similar to sea lamprey, and (3) ovulated females of species native to the Great Lakes were attracted to conspecific male odors, ovulated female sea lamprey were attracted to heterospecific male odors, and only male and female chestnut lamprey were attracted to 3kPZS. We also found that larval released 3kPZS likely acts as a migratory cue in silver lamprey, and that all species exhibit olfactory sensitivity to 3kPZS. Taken together, our results indicate that all lamprey species likely employ mating pheromones and that these pheromones are partially shared among species. Because pheromones are partially shared, potential confounding effects of pheromones released by native lampreys should be considered when using 3kPZS for sea lamprey control; native lamprey pheromones could obscure synthesized pheromone plumes intended to attract sea lamprey. Chestnut lamprey are most likely to be influenced by application of 3kPZS because they also use 3kPZS as a major component of their mating pheromone. However, any negative effects of 3kPZS application are still expected to be less than the negative effects associated with lampricide application because any trapped native lampreys can be sorted from sea lamprey and released.