Differential diagnosis of Triaenophorus crassus and T. nodulosus experimental infection in Cyclops abyssorum praealpinus (Copepoda) from the Alpine Lake Grundlsee (Austria) using PCR–RFLP

Abstract

In 2005, an epidemic of the cestode Triaenophorus crassus in Arctic charr, Salvelinus umbla from Lake Grundlsee (Austria) was reported, resulting in the closure of the local fisheries. The parasite uses a copepod and a salmonid fish as intermediate hosts, and the European pike (Esox lucius) as definitive host. In Lake Grundlsee procercoids of T. crassus, T. nodulosus and Eubothrium salvelini use the copepod Cyclops abyssorum praealpinus as their first intermediate host. We report on the development of a PCR-RFLP assay for the specific differentiation between the procercoids of the three cestode species. Ban I restriction sites within a 207-bp 18S rRNA-amplified fragment yielded two and three species-specific products to unequivocally distinguish between T. crassus and T. nodulosus, respectively. The assay is sufficiently sensitive to characterise a single procercoid of both Triaenophorus species in their copepod host, enabling a direct measure of infection. This assay will be useful in monitoring the progress of the control methods currently in place.

Infestation of zooplankton with Triaenophorus and Proteocephalus procercoids (Cestoda) in a deep oligotrophic lake

“…Between 100 and 515 (mean: 305) individual copepods per sample were examined under a stereo microscope and opened (when infested) N o n -c o m m e r c i a l u s e o n l y with dissection needles to release the tapeworm larvae for a more detailed determination under an inverted microscope (Leitz Labovert, Leica Microsystems, Wetzlar, Germany; 40 to 640-fold magnification). Because of their uniform morphology, molecular biological methods are necessary to identify the procercoids of the genus Triaenophorus to species-level (Boufana et al, 2011). In a fish survey taking place at the same time as the present study, the second intermediate hosts, C. lavaretus and S. umbla, were exclusively infested with T. crassus, while T. nodulosus was found in brown trout Salmo trutta (Schähle and co-workers, personal communication).…”