engleski

The mechanisms of infection of the buccal isopod Ceratothoa oestroides (Risso, 1836), under experimental conditions

Two annular sea bream (Diplodus annularis) and eight sea bream larva (Sparus aurata) were artificially infected with Ceratothoa oestroides pulli II in experimental conditions. Infective stage of C. oestroides pulli II are free-swimming, aggressive and capable of infection 7 days after staying on a fish host. After leaving the female, they swim vigorously on the water surface, attach themselves to a host's body surface and migrate rapidly under the operculum in the buccal cavity. This observation contradicts the earlier presumption that juvenile fish regard the isopod pulli II as attractive "live food" and swallow them in concordance with their hunting behavior. Successful attaching to the host is achieved in two hours. Superinfection is rarely possible, and only up to two isopods are generally hosted in one fish. In case of three or more pulli, strong competitive mechanisms are observed, resulting in the unpaired pulli detaching from the buccal cavity or remaining on the exterior on the body surface. The percentage of experimental infection in this study was 58, 8, 13, 63 and 100% in different aquaria, depending on host size. Also, strong positive correlation between isopod and fish length was found (r = 0, 94, p < 0, 05).

bass Dicentrarchus labrax; Cymothoidae; parasite; fish

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