Sexual selection of parasites in Nile tilapia (Oreochromis niloticus L.)

Abstract

This study was specifically conducted in order to determine the possible influence of host sex in the prevalence and intensity of parasites in Nile tilapia (Oreochromis niloticus L.). The present study recorded six genera of ectoparasites and three taxa of endoparasites from the gills, skin and intestine of the examined Nile tilapia that were collected from grow-out farms in Central Luzon, Philippines. Female tilapia had higher prevalence in most of the parasites identified such as Trichodina, Dactylogyrus, Gyrodactylus, Coleps, Euplotes, Ergasilus and digenean as compared to male samples. Meanwhile, the prevalence of Camallanus was higher in males as compared to females. Female tilapia parasitized with Trichodina, Dactylogyrus, Euplotes, Ergasilus and digenean showed higher intensities as compared to males. In contrary, the intensities of Gyrodactylus, Coleps and Camallanus were higher in male tilapia than in females. The main reason for the differences in parasitic load with sex is thought to be physiological.