Prevalence of Oestrus ovis(Diptera: Oestridae) in sheep from the São Paulo Central region, Brazil

The heads of 139 slaughtered sheep were examined with the aim of determining Oestrus ovis prevalence and infestation intensity in the central region of the State of São Paulo, Brazil. Heads from slaughtered sheep were examined and the first (L1), second (L2) and third (L3) O. ovis larval instars were recovered from the nasal and sinus cavities. O. ovislarvae were detected in 13.7% of the sheep analyzed. The monthly mean intensity of infestation ranged from 1 to 10.2 larvae per infested head, with general mean intensity of 4.5 larvae/infested head. Of the total of 85 larvae, 21.2% were L1, 37.6% L2 and 41.2% L3. In conclusion, all different O. ovis larvae instars were recovered from slaughtered animals, which demonstrates the existence of favorable climatic conditions for the fly activity and larval development of O. ovis in sheep raised in the Central region of the State of São Paulo.

本研究以巴西圣保罗州中部地区羊狂蝇（Oestrus ovis）的感染率与感染强度为检测目标，对139头屠宰绵羊的头部样本开展检验。研究人员对屠宰绵羊的头部样本进行解剖，从鼻腔与鼻窦腔内分离得到羊狂蝇的第一期（L1）、第二期（L2）及第三期（L3）幼虫。经检测，13.7%的受检绵羊呈现羊狂蝇感染阳性。月度平均感染强度介于1至10.2条幼虫/感染头份之间，整体平均感染强度为4.5条幼虫/感染头份。在总计分离得到的85条幼虫中，L1期幼虫占比21.2%，L2期占比37.6%，L3期占比41.2%。综上，本研究从屠宰绵羊体内分离得到了全部发育阶段的羊狂蝇幼虫，证明圣保罗州中部地区的绵羊养殖环境具备适宜该蝇类活动及羊狂蝇幼虫发育的气候条件。