Biomphalaria havanensis is a Natural First Intermediate Host for the Trematode Bolbophorus damnificus in Commercial Catfish Production in Mississippi

Abstract

AbstractThe digenetic trematode Bolbophorus damnificus is a significant hindrance to the production of farm‐raised catfish in the southeastern USA. Severe infections with Bolbophorus damnificus can result in death, but the real damage lies in mild to moderate infections, which can go unnoticed by producers. Research has shown even mild infections can inhibit production to the point of operating at a net loss. The ramshorn snail Planorbella trivolvis is the first intermediate host for Bolbophorus damnificus and is prevalent in most commercial catfish ponds in the Southeast. Management practices aimed at controlling Bolbophorus damnificus infections primarily focus on reducing snail populations in ponds. Other aquatic snail species are also commonly associated with commercial catfish ponds, although little is known about their contributions to trematode infections in catfish. In the summer of 2014, 804 snails Biomphalaria havanensis (synonym: Biomphalaria obstructa) were collected from a single commercial catfish pond and screened for trematode infections. Seven of these snails (0.81%) were actively releasing cercariae identified molecularly as Bolbophorus damnificus. These cercariae were subsequently used in infectivity trials with Channel Catfish Ictalurus punctatus fingerlings (5–8 cm). Seven days postchallenge, fish were examined histologically for the presence of metacercariae, which were present in 13 of 15 (86.67%) surviving fish. This is the first report of naturally occurring infections of Bolbophorus damnificus in another snail species.