Safety and Effectiveness of Trichlorfon in Prevention of Lernaeosis and Its Comparison with Plant Extracts in Lernaeosis Control

Abstract

This study was carriedout to evaluate the safety and effectiveness of trichlorfon in prevention oflernaeosis among hatchery-reared cyprinids. Also, it compared with plantextracts (carvacrol and cymene mixture and thyme) in lernaeosis control. At theAbo-Saleh fish hatchery in BeniSuef, Egypt, the trichlorfon bioconcentrationsof cyprinids fries and fingerlings, as well as soil, water and plant sampleswere examined for 2 years. Trichlorfon was detected in fingerlings, water andplant samples, except soil sampled 1 hr after trichlorfon was applied to thefish pond. The highest concentration of trichlorfon was in fish, followed bywater and plant samples. No trichlorfon was detected in fingerlings, water,plant and soil sampled after 5 days and 5 months. Fingerlings and brooders ofcyprinids were examined in situ for clinical abnormalities and prevalence oflernaeosis. In addition, the intensity of the lernaea infestation wasdetermined. Macroscopic Lernaea cyprinacea females were seen attached to theskin and fins associated with swollen hyperemic nodules and open wounds.Lernaeosis appeared sporadically during examination seasons with a highintensity. Under experimental condition, trichlorfon succeeded in controllinglernaeosis among Ctenophyrngedon idella fingerlings, as it eliminated 100% ofLernaea cyprinacea in comparison with 74.28% and 50.2% in carvacrol and cymenemixture and thyme treated fish respectively.