Abstract:
Dactylogyrus extensus is a common, economically significant
pathogenic monogenean ectoparasite of Cyprinus carpio. It attaches
itself to its host by means of an opisthaptor containing two hamuli, a
connecting bar and 14 marginal hooks.
Smaller D. extensus which are found in higher numbers in fish
presumably represent the recently invaded individuals. Large worms are
found in lower numbers. D. extensus does not need to attach itself to the
host tissue to initiate egg laying. The rate of egg laying varies with the
environmental temperature. The first eggs that are produced in-vitro are
of larger size but as oviposition continues the size of the egg becomes
smaller.
The mean oviposition rates were 2.03, 1.97, 1.45 eggs-1worm-1 at
11°C, 13°C and 19°C respectively. The time taken to lay an individual
egg was calculated as 29.60 mins, 30.45 mins and 41.38 mins at 11°C,
13°C and 19°C respectively.
