[Bacillary necrosis in larvae of the bivalve Euvola ziczac (Linnaeus, 1758) caused by a Pseudomonas sp].

The incidence of bacteria as etiological agents of diseases in larvae of bivalve mollusks, is well documented in the literature. In this study, a series of test were performed to identify and estimate pathogenic level of marine bacteria isolated during an epizootic in a larval culture system of the tropical scallop Euvola ziczac. Such bacteria was identified as Pseudomonas sp. belonging to the group alcaligenes. The bacterium produced not only lethal effects on the scallop larvae through infection (invasive action), but also a possible pathogenic activity through endotoxins associated to bacterial cell-wall. In addition, it is possible that the isolated bacteria could act as a pathogen with members of the genus Vibrio, which was also present during the epizootic outbreak in the culture system. Susceptibility of Pseudomonas sp. to commercial antibiotics was remarkable.