Prevalence of cymothoid isopods (Crustacea, Isopoda) and proximate analysis of parasites and their host fishes, Southeastern India

Changes in the proximate and elemental composition of Alitropus typus (Crustacea: Flabellifera: Aegidae) exposed to lethal dose of bacterial consortium

Alitropus typus is a crustacean parasite, which is increasingly becoming a menace to aquafarmers. In our previous study, a novel microbial consortium comprising of three exoskeleton degrading bacterial strains (Stenotrophomonas maltophilia, Bacillus altitudinis and Klebsiella pneumoniae) had shown promising results as a biocontrol agent for A. typus. The present investigation reports the changes in proximate and elemental composition associated with the application of microbial consortium on the isopod A. typus. Proximate analysis showed an increased level of protein, lipid, and moisture in treated isopod at 48 h compared with untreated isopod. However, ash and chitin concentrations were lower in treated isopod. The elements in the mid-tergite of untreated isopod was compared with the treated isopod at 48 h using scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDAX). The following elements were analyzed in the mid-tergite segment of untreated isopod: C, O, Na, Mg, Al, Si, P, S, Cl, K, Ca and Fe. The results showed that the concentration of calcium had decreased significantly in the treated isopod at 48 h (4.28 ± 0.11%) when compared to the untreated isopod (10.01 ± 0.32%), indicating that the bound form of calcium carbonate in the exoskeleton had been precipitated by microbial action. The concentration of carbon and phosphorous was higher in the treated isopods at 48 h compared to the untreated ones. The data suggests that treatment with microbial consortium is not only an effective but also an environmentally safe alternative for the control of A. typus.

Occurrence of Isopods in Two Species of Snappers (Lutjanidae) from Northeast Brazil

Parasitic isopod species are poorly known in the northeastern coast of Brazil. In this sense, this study presents novel records of Isopoda of the families Aegidae, Cymothoidae, and Corallanidae. A total 69 specimens of Lutjanus analis and 19 of Lutjanus jocu, of which 46 isopods from 3 different species were collected, i.e. Rocinela signata, Cymothoa excisa, and Excorallana richardsoni. The species R. siganata and E. richardsoni are reported for the first time in L. jocu. A significant relationship between the parasite R. signata and the size of the fish L. jocu was also observed. The isopod C. excisa is considered an incidental finding in L. analis. To the authors' knowledge, this is the first report of this species in fish from Brazil. The three species of isopods are new occurrences in the State of Sergipe, northeast region of the country. An additional morphological characteristic observed in the dorsal setae of pleotelson in specimens of E. richardsoni was that one end of this structure wws bifid. This information contributes to the current body of knowledge of the morphology of this particular species.