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Development of a controlled-release polymer for deployment of the sea lamprey pheromone 3-keto-petromyzonol sulfate
James E. Hanson1 and C. Michael Wagner2
1Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, NJ
2Michigan State University, Department of Fisheries and Wildlife, East Lansing, MI
This research project had the following goals: 1) Develop a cost-effective and environmentally benign polymer-based emitter for deployment of 3kPZS as a sea lamprey control tool; 2) Ascertain the performance of the best polymer candidates in a natural stream (e.g., dissolution rate, release rate, realized 3kPZS concentration); and 3) Ascertain whether the 3kPZS-impregnated polymer elicits a sufficiently strong behavioral response from ovulatory female sea lamprey in a natural stream to merit its inclusion in an application to the US EPA to register 3kPZS under FIFRA. These goals were all achieved, and a more extensive field test was performed using the emitters as baits in trapping studies during the no-cost extension period.
Our success in achieving goal 1 was described in our 2011 annual report, including the evaluation of a variety of polymers for dissolution in vitro and in an artificial stream on the basis of the release of Rhodamine WT dye. This led to the selection of polyethylene glycol (PEG) with an average molecular weight of 6000 as the polymer for the emitters. The 2011 report also described our efforts toward the completion of Goal 2. At the time our 2011 report was submitted, we had prepared prototype emitters containing 3kPZS and had evaluated release from the emitters using a HPLC method we had developed, with Dansyl derivatization of 3kPZS to allow UV-Vis detection. At that time we were also waiting for our EPA experimental use permit, which came through in time for field studies in 2011. Those field studies resulted in the completion of goal 2: evaluation of the dissolution rate, the release rate and 3kPZS concentration. Further work in 2012 gave us a better understanding of how the shape (length and diameter) of the polymer emitter can regulate the release rate, and how a baffle system can reduce the impact of flow and turbulence on dissolution.
Goal 3 was successfully completed in our 2011 field work and in further work completed in 2012. This work demonstrated a strong behavioral response from female sea lamprey in natural stream environments. Our 2011 field work was completed as planned, using PIT tags and antennas to track the response of ovulatory female sea lamprey. The response was strong, with ~75% of test animals choosing the 3kPZS emitter over the control. In 2012, in collaboration with Dr. Nick Johnson, we supplied 250 emitters for baiting traps in four rivers (Cheboygan, Manistique, Muskegon, and Carp Lake Outlet). The use of the emitter baits in the traps appeared to enhance the success of the trapping operation, with an average yield increase of 31% in the baited traps, and a 57% increase in the best case.
In summary, we have developed an effective way to employ 3kPZS in the field. The polymer emitters can be readily prepared, are stable and easily handled, and can be deployed simply (they do not require extensive training or any other equipment) in the field. The baffle system and the timer delivery mechanism we developed to bait traps have practical implications for use in the field as well. The results of this project prepare the way for the widespread employment of 3kPZS and other pheromones in sea lamprey control.