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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03490

    Livoneca redmanii (Isopoda, Cymothoidae) in meagre Argyrosumus regius: parasitological and molecular diagnosis with control measure

    Amr Fadel*, Mohamed Bessat, Mohamed Abdel-Aziz

    *Corresponding author:

    ABSTRACT: Isopodiosis in cultured meagre Argyrosumus regius was investigated in three farms in the northern lakes of Egypt throughout 2018, based upon prevalence rate, parasitological examination, and molecular identification by PCR targeting the large ribosomal subunit 16S of the rRNA gene. Further, the susceptibility of A. regius to isopod infection was experimentally evaluated under hyposalination of 33, 25, 15, and 8 ppt for 1 wk. The isolated isopod stages were morphologically identified as Livoneca redmanii Leach, 1818 with prevalence rates of 77.05 and 77.9% in Al-Madiyyah and Sidi Krir, respectively. The highest prevalence and salinity rates of 78.85%, and 30–34 ppt, respectively, were reported in El Matareya farm. DNA sequencing and molecular analysis confirmed the classification of L. redmanii. A. regius experimentally infected with L. redmanii under a hyposalination protocol at 15 and 8 ppt showed marked reduction in mortality (20% and 50%, respectively), and infection prevalence (40% and 63.33%, respectively). Also, the serum lysozyme concentration and nitric oxide of treated fish at 15 and 8 ppt were significantly increased compared to those in 25 and 33 ppt. The serum osmolality levels were higher at 25 and 33 ppt. To the best of our knowledge, this is the first molecular characterization of L. redmanii in cultured A. regius in Egypt.