Acquired resistance of bluegill sunfish Lepomis macrochirus to glochidia larvae of the freshwater mussel Utterbackia imbecillis (Bivalvia: Unionidae) after multiple infections.

The effects of multiple infections on the host-parasite relationship between bluegill sunfish (Lepomis macrochirus) and parasitic glochidial larvae of the freshwater mussel Utterbackia imbecillis were examined. Naïve, young-of-the-year bluegills were infected with glochidia and placed in individual observation chambers. Each day, water was drained from each chamber and the numbers of dead glochidia, live glochidia, partially metamorphosed glochidia, and fully metamorphosed juvenile mussels were counted.