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Abstract

A single application of Oimilin (UNIROYAL),diflubenzuron, was tested in 9 (nine) ponds containing golden shiner minnows, Notemigonus crysoleucas, infested with the parasitic copepod Lernaea cyprinacea. The chemical was applied at a rate of1 0 or 30 pg/l and compared to untreated controls. Fish were periodically sampled to determine levels of infestation, and zooplankton numbers were monitored for chemical effect. Oimilin treatment significantly reduced (P < 0.05) parasite infestation four to eight days after treatment. No significant difference (P < 0.05) was noted between the two levels of treatment. Zooplankton populations decreased in the Dimilin treated ponds following chemical application. Rotifer populations rebounded later during the period, but copepod populations in the ponds treated with 30 ng/L remained depressed from two days after treatment for one month until the study ended. Complete parasite control was not obtained with either chemical concentration using a single application. These results suggest that a single treatment is not effective for Lernaea control. Future research will test two applications 10 days apart at the 10 and 30 /xg/L levels.

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