Abstract

This study was conducted in Borena pastoral area, southern rangeland of Ethiopia to determine the in vitro efficacy of amitraz 0.025% and diazinon 0.06% against Rhipicephalus pulchellus and Amblyomma gemma using modified adult immersion. A total of 180 engorged adult female ticks (ninety ticks of each A. gemma and R. pulchellus species) were immersed in amitraz 0.025% or diazinon 0.06% at field recommended concentration (treated groups), or in distilled water (control groups) for 10 min and then incubated at 27 ± 1°C for 7 days. The oviposition response of each tick species in both groups was followed. The mean mass of eggs laid by each A. gemma and R. pulchellus in the treated group and those of untreated groups was compared to estimate the efficacy of each tested acaricide. Amitraz 0.025% has significantly higher (P < 0.05) in overall mean percent oviposition control (C% = 95.47) of A. gemma and R. pulchellus than diazinon 0.06% (C% = 80.9). At this recommended concentration, both amitraz 0.025% and diazinon 0.06% were less efficient in R. pulchellus oviposition control (C%= 90.94 for amitraz and C% = 71.41 for diazinon) than A. gemma oviposition control (C% = 100 for amitraz and C% = 88.85 for diazinon). The results of the study suggested that amitraz at field recommended concentration provides better efficient R. pulchellus and A. gemma oviposition inhibition than diazinon.

Key words: Amitraz, diazinon, Borena pastoral area, cattle, efficacy, in vitro testing, Amblyomma, Rhipicephalus.