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Diseases of Aquatic Organisms

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DAO 140:13-24 (2020)  -  DOI: https://doi.org/10.3354/dao03490

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

Amr Fadel1,*, Mohamed Bessat2, Mohamed Abdel-Aziz3

1Laboratory of Fish Diseases, Aquaculture Division, National Institute of Oceanography and Fisheries NIOF, El-Anfoshy, Qaitbay Bay Castle, Alexandria, 21556, Egypt
2Department of Parasitology, Faculty of Veterinary Medicine, Alexandria University, Abbis 10, Alexandria, 22758, Egypt
3Laboratory of Fish Rearing, Aquaculture Division, National Institute of Oceanography and Fisheries NIOF, Inland Water Branch, Fayoum, 63511, Egypt
*Corresponding author:

ABSTRACT: Isopodiosis in cultured meagre Argyrosomus regius was investigated at 3 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 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 of 78.85% and 30-34 ppt were reported in El Matareya. DNA sequencing and molecular analysis confirmed the identification 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). The serum lysozyme concentration and nitric oxide of treated fish at 15 and 8 ppt were significantly increased compared to those held at 25 and 33 ppt, whereas serum osmolality levels were higher at 25 and 33 ppt. To our knowledge, this is the first molecular characterization of L. redmanii in cultured A. regius in Egypt.


KEY WORDS: Meagre · Argyrosomus regius · Cymothoid isopod · Prevalence · DNA sequencing · Hyposalination


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Cite this article as: Fadel A, Bessat M, Abdel-Aziz M (2020) Livoneca redmanii (Isopoda, Cymothoidae) in meagre Argyrosomus regius: parasitological and molecular diagnosis and proposed control measure. Dis Aquat Org 140:13-24. https://doi.org/10.3354/dao03490

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