The efficacy of two synthesized sea lamprey sex pheromone components as a trap lure when placed in direct competition with natural male odors

The female sea lamprey (Petromyzon marinus), a devastating invasive fish of the Laurentian Great Lakes, locates potential mates by tracking a sex pheromone emitted by nesting males. We tested whether combinations of two putative components of the sex pheromone, 3-keto-petromyzonol sulfate (3kPZS) and 3-keto-allocholic acid (3kACA), were sufficiently attractive to function as a trap-bait when placed in direct competition with male odors. Ovulating females successfully located point sources of 3kPZS both in the presence and absence of a competing odor emitted by mature males placed upstream. However, 3kPZS was not able to retain females in the vicinity of a trap longer than two minutes, and retention time was reduced by 57% when competing male odors were present. 3kACA failed to elicit a response on its own and did not improve attraction to, or retention near, a source of 3kPZS. Application of an incomplete pheromone in trapping-for-control scenarios will require devices configured to minimize the effort necessary to enter a trap, features to offset the probable decrease in trap retention, and deployment into favorable habitats where competition with spawning males is minimal.