Cross-Resistance of Largemouth Bass to Glochidia of Unionid Mussels

Abstract

We tested whether host fish that acquired resistance to glochidia of one mussel species were cross-resistant to glochidia of other species. Largemouth bass (Micropterus salmoides) were primed with 4-5 successive infections of glochidia of Lampsilis reeveiana. The percentage of attached glochidia that survived and transformed to the juvenile stage (transformation success) was compared between primed fish and naïve controls. Transformation success of L. reeveiana, Lampsilis abrupta, Villosa iris, and Utterbackia imbecillis was significantly lower on primed fish (37.8%, 43.5%, 67.0%, and 13.2%, respectively) than on control fish (89.0%, 89.7%, 90.0%, and 22.2% respectively). Immunoblotting was used to analyze the binding of serum antibodies from primed fish with glochidia proteins. Antibodies bound to glochidia proteins of similar molecular weight from L. reeveiana and L. abrupta. Bound proteins of V. iris differed in molecular weight from those of the Lampsilis species. There was no binding to specific glochidia proteins of U. imbecillis or Strophitus undulatus. Our results indicate that host-acquired resistance can extend across mussel genera and subfamilies and might involve both specific and nonspecific mechanisms. Understanding the specificity of acquired resistance of hosts to glochidia could enhance understanding of the evolutionary and ecological relationships between mussels and their host fishes.

An alien fish threatens an endangered parasitic bivalve: the relationship between brook trout (Salvelinus fontinalis) and freshwater pearl mussel (Margaritifera margaritifera) in northern Europe

“…However, there are also examples of invader being as good a host as the native species for the native parasites (Poulin andMouillot 2003, Brandner et al 2013). The potential natural (Langefors et al 2001) and acquired (Young and Williams 1984a, Bauer 1987b, Dodd et al 2005, Treasurer et al 2006) immune responses of hosts against parasites may also affect host-parasite co-evolution. Moreover, FPM has a much longer lifespan and higher maturation age and hence a longer generation time than the salmonids host, being thus an extraordinary parasite (Kaltz and Shykoff 1998, Gandon and Michalakis 2002, Greischar and Koskella 2007, Geist and Kuehn 2008.…”

Persistence of host response against glochidia larvae in Micropterus salmoides

“…Glochidia harvest and host infection methods were similar to those used previously [17]. Fish were infected with glochidia by placing them as a group in a suspension containing 2000 infective glochidia L ÿ1 , for 15 min.…”

“…These tanks were part of a recirculating system (AHAB Ò Aquatic Habitats, Inc. Apopka, FLA). The system was modified for monitoring metamorphosis success of mussel glochidia on fish, as described previously [17]. We counted the glochidia and juveniles shed from each fish at 1 day post infection (dpi), and every 2 days thereafter until no more glochidia or juveniles were recovered from any fish.…”

“…Methods used for analyzing serum antibodies were similar to Dodd et al [17]. Subgroups of the primed and control fish were sacrificed at intervals to determine presence or absence of serum antibodies.…”

“…Several studies have reported ''anti-glochidia factors'' (presumably antibodies) in the serum of infected host fish [7,10,16]. Antibodies from primed fish bind glochidia proteins and may be involved in acquired resistance [17]. However, specific cell-mediated and non-specific immune factors have not been ruled out as potential mechanisms.…”