Seasonal prevalence of Oestrus ovis L. (Diptera: Oestridae) larvae in infested sheep in Jazan Region, Saudi Arabia

Oestrus ovis L. (O. ovis) (Diptera: Oestridae) is a cosmopolitan agent of myiasis in sheep and goats. Sneezing and nasal discharges are the major clinical signs in infested animals. The present study was carried out to estimate the annual abundance of O. ovis in randomly selected male sheep heads in Jazan region. Survey conducted weekly for O. ovis during the period from November, 2010 to October, 2011, from Slaughterhouses in Jazan and the ecological data including, temperature, relative humidity, were obtained from the Department of Meteorology, Jazan. The study investigated 480 sheep heads. The collected larval specimens were identified by British Museum (Natural History), London. Results indicated that 257 (53.54%) of the total examined sheep heads showed positive infestation. Infestation recorded four peaks at January, May, July and October. The highest infestation was detected at January (82.5%), while the lowest was at August (25.00%). Also, the first, second and third larval instars represented 3.02, 20.35, and 76.63% from the total collected larvae, respectively. The data represented mean larval monthly number per sheep head. The study suggested the cold seasonal related O. ovis infestation in Jazan region. Key words: Jazan, Oestrus ovis, sheep, seasonal prevalence, abundance.