An experimental study of the biology of Bothriocephalus acheilognathi Yamaguti, 1934 (Cestoda: Pseudophyllidea)
Bothriocephalus specimens from a single 0+ Ctenopharyngodon
idella were fixed using three different techniques, and the scolex
morphology was examined using scanning electron microscopy. The
scolices were compared with the five species of Bothriocephalus and
one species of Schyzocotyle previousley recorded from cyprinid
fishes. The taxonomic history of the Bothriocephalus species
parasitising cyprinid fishes was reviewed. It was concluded that
the six species were synonymous, and that priority should be given
to the name B. acheilognathi Yamaguti, 1934; with B.
opsariichthydis Yamaguti, 1934, ~fluviatilis Yamaguti, 1952, ~
gowkongensis Yeh, 1955, .!h. phoxini Molnar, 1968 and Schyzocotyle
fluviatilis as synonyms.
A critical examination of the three species of Bothriocephalus
reported from cyprinid fishes in Africa is presented. The
characters examined did not enable the species to be differentiated,
therefore it is suggested that ~ aegyptiacus Rysavy and Moravec,
1975 and B. ki vuensis Baer and Fain, 1958 are synonyms of B.
Laboratory experiments revealed that establishment, development
and mortality of each stage of the life cycle of ~ acheilognathi
was temperature dependant. In addition the infectivity of the
coracidium and procercoid was age dependant. Development of the
procercoid was influenced by the age of the coracidium when ingested
by the copepod intermediate host, and the infecti v i ty of the
procercoid was inversely related to the density of ~e. procercoids
within the intermediate host.
Estimation of the time taken for the completion of the life cycle at temperatures ranging from 18-30 0c showed it to be
inversely related to temperature. The size of the Cyprinus carpio
host influenced the ability of the plerocercoids to establish, with
no establishment occuring in C. carpio greater than 63 mm fork
The strobila of ~ acheilognathi was observed to undergo a
cyclical pattern of contraction and relaxation within the host
intestine. The frequency of this behaviour was associated with the
feeding behav iour of the .f:. carpio host. No significant variation
in scolex position was observed. Egg release by B. acheilognathi
also followed a cyclical pattern,with peak egg production occurring
shortly after the entry of food into the intestine.
Praziquantel (Droncit, Bayer) was found to be a suitable
anthelmintic for the control of ~ acheilognathi. In vitro studies
indicated that praziquantel concentrations of 0.1ug per ml 0.9%
saline and above, caused muscular contraction and severe tegumental
damage. Exposure to drug concentrations of 100 ug praziquantel per
ml saline for 24 hours was not lethal to the worms. Praziquantel
had no ovicidal activity.
Praziquantel was used to eliminate ~ acheilognathi from a
batch of 30,000 newly imported Ctenopharyngodon idella. Dose rates
of 105 and 125 mg praziquantel kg bodyweight-1 administered as a
medicated feed over a three day period were used. The fish were
raised to 240c in an indoor recirculating unit prior to treatment.
The ponds containing infected fish were drained and limed to kill B.
acheilognathi ova and copepods.