Influence of Temperature and Parasite Intensity on Egg Production and Hatching of the Monogenean Dactylogyrus extensus

Dactylogyrus extensus is a species of monogenetic flukes of the family Dactylogyridae that infests cultured as well as wild fish. Understanding its reproductive biology would help control its population. Temperature and parasite intensity influence egg production and larvae hatching. Therefore, we investigated the effect of these parameters on egg production in vivo and in vitro of D. extensus taken from the gills of Cyprinus carpio at 10 degrees C and 17 degrees C, and on larvae hatching at 10 degrees C, 17 degrees C, and 25 degrees C. Temperature significantly effected both egg production and larvae hatching. A significantly greater number of eggs was produced at 17 degrees C than at 10 degrees C, but the hatching rate was higher and more rapid at 25 degrees C. Egg production in vitro was relatively higher than in vivo. Eggs were resistant to cold water and larvae development was inhibited at 2-3 degrees C. However, when the temperature was increased, larvae development commenced and hatching was observed.