Effect of an Otic Milbemycin Oxime Formulation on Tegastes acroporanus Infesting Corals

Abstract

The copepod Tegastes acroporanus is a notorious pest of captive corals in the genus Acropora. In recent years, infestations of T. acroporanus have become widespread among public aquaria and coral propagation facilities and have been largely controlled with the extra-label use of milbemycin oxime formulations (Carl 2008). Many of these drug formulations (which were intended for dogs) have been discontinued by their manufacturers in favor of multidrug products, many of which are unsuitable for corals, forcing experimentation with alternatives. This report provides the first data on populations of T. acroporanus treated with milbemycin oxime and documents the first known use of an otic solution, MilbeMite Otic (Novartis Animal Health U.S., Greensboro, North Carolina), against copepods on live corals. MilbeMite Otic was found to be soluble in seawater and successful at eradicating T. acroporanus in a large exhibit over the course of 6-h waterborne baths (n = 12) at 0.167 µg/L. The resident population of T. acroporanus was also quantified before each treatment to provide the first estimates of coral parasite burden in response to the application of a waterborne chemotherapeutic agent.

Received November 19, 2015; accepted June 7, 2016 Published online October 24, 2016

Acknowledgments

Thanks to the Coral Disease Group of the AZA Aquatic Invertebrate Taxon Advisory Group for feedback on this issue and to R. Brynda and J. Frey Sr. (Landry’s Aquariums), N. Ireland (Sea World), S. Snowden (Pittsburgh Zoo), C. Bonar, S. Walker, and M. Connolly (Dallas Zoo), and M. Henley (Smithsonian Institution) for their assistance with this project.