Dominance of Dibothriocephalus ditremus over Dibothriocephalus dendriticus (Cestoda: Diphyllobothriidea) in salmonids from Lake Kalandsvatn (Western Norway) revealed by molecular genotyping

Abstract

The occurrence of Dibothriocephalus dendriticus and Dibothriocephalus ditremus in salmonids (brown trout Salmo trutta and Arctic charr Salvelinus alpinus) from Lake Kalandsvatn in Western Norway was studied. Plerocercoids were identified by external morphology and PCR-based analysis using Dd_8 microsatellite primers. Of 1313 plerocercoids, 121 (9.2%) were identified as D. dendriticus and 1192 (90.8%) as D. ditremus. The study provides the first record of D. ditremus in Lake Kalandsvatn. The prevalence of D. dendriticus was 51.3% in trout and 76.9% in charr, while D. ditremus prevalence was higher (76.9% in trout and 100% in charr). The intensities of D. dendriticus infection were also lower (trout 1–17; charr 1–20) compared to D. ditremus (trout 1–221; charr 2–86). The higher relative abundance of D. ditremus compared to D. dendriticus was detected in most trout and charr. The dominance of D. ditremus probably reflects the feeding strategies and the higher abundance of its definitive hosts, piscivorous birds.