Ixodid ticks infesting cattle in three agroecological zones in central Oromia: species composition, seasonal variation, and control practices

Abstract

A cross-sectional study was conducted to determine the species, prevalence, and seasonal variation of ticks on cattle in central Oromia. In addition, questionnaire survey was used to assess the control practices of ticks in central Oromia. During the study period from August 2008 through April 2009, a total of 10,440 adult ixodid ticks were collected from a total of 918 cattle (153 cattle during dry and wet seasons from each of three agroecologies) in three agroecological zones during wet and dry seasons. A total of seven species of ixodid ticks belonging to four genera were identified during the wet period, whereas similar numbers of genera but six species of ixodid ticks were recorded during the dry season. Amblyomma, Boophilus, Rhipicephalus, and Hyalomma tick genera were identified during the two seasons. Five different species of ticks were identified from the highland altitude. Significantly (p < 0.05) higher proportion of Boophilus decoloratus (88.2 %) was identified during the wet season, Hyalomma truncatum (1.5 %) was with the least proportion. Rhipicephalus evertsi evertsi (50.8 %) was the most abundant during the dry period, whereas Hyalomma marginatum rufipes (5 %) was with smallest proportion. In the midland, a total of six species of ticks were identified. Significantly (p < 0.05) higher proportion of Amblyomma variegatum (76.6 %) than the other species was recorded during the wet season in the midland. But Rhipicephalus pulchellus (0.05 %) was collected with the lowest proportion. R. e. evertsi (46.3 %) was the most abundant tick species during the dry season, whereas R. pulchellus (0 %) was with lowest proportion. In the lowland, a total of seven species of ticks during the wet and six during the dry season were identified. A significantly (p < 0.05) higher proportion of A. variegatum (30.3 %) was recorded during the wet season, whereas R. pulchellus (1.4 %) was identified with the lowest proportion in the lowland. R. e. evertsi (24.8 %) was the most abundant tick species during the dry season in the lowland, but R. pulchellus (0 %) was with the lowest proportion during the same season in the lowland. Results of the study revealed that the highest mean total tick burden was recorded during the early rainy season than the dry season from the end of March to April. And the lowest mean tick count was recorded during the early dry and the late dry season during December and February, respectively. The overall tick count across seasons showed significant variation (F = 114 and p = 0.000). The questionnaire survey on the tick control practices has revealed that (90 %) diazinon and (57.3 %) cypermethrin were the commonly used acaricides with a frequency of one to three times per year during the peak of tick infestation. In conclusion, this study demonstrated that ixodid ticks occur with high prevalence and burden and still play major roles in reducing productivity of cattle and cause health problems of cattle in central Oromia. Further studies on the role of ticks in the transmission of pathogens to cattle, other animals, and zoonotic pathogens to man in Oromia are urgently needed.