Brown spot disease: un fattore limitante la riproduzione controllata di mazzancolla (Melicertus kerathurus) (Forskäll, 1775)

Melicerthus (Penaeus) kerathurus commonly named "caramote prawn", is a specimen very appreciated and recently proposed as a new species for reproduction. The hatching and larval stages are very sensitive to the microbial attack and the mortality is higher than the other stages of life. Vibriosis is the bacterial disease most common in larvae and post-larvae causing high mortality (about 80%) in few time, the species involved in this pathology are Vibrio alginolyticus, V. parahaemolyticus e Listonella (Vibrio) anguillarum, these Vibrios act as opportunistic bacteria and in stress conditions become dangerous for fish health. Here we reported a Brown Spot Disease episode occurred during a controlled reproduction experiment of M. kerathurus. Adult specimens showed brown-green ulcers on carapace, thorax, abdomen and in same specimens on pereiopods. Sampling of lesions and water has been effectuated to identify the pathogen agent by microbial and histochemical methods. The results showed that all subjects were infected by V. alginolyticus and that confirm the opportunistic "nature" of this bacteria, that in stress conditions (sub-optimal environment, low water quality, high stock density or high manipulation) become pathogen.