In vitro acaricide efficacy evaluation on Ambylomma variegatum and Rhipicephalus (Boophilus) decoloratus ticks infesting cattle in the Gondar Zuria District, Northwest Ethiopia

IF 2.4 Q3 INFECTIOUS DISEASES

Parasite Epidemiology and Control Pub Date : 2026-05-01 Epub Date: 2026-04-25 DOI:10.1016/j.parepi.2026.e00507

Bizuayehu Meskele Tafese , Moges Maru , Zewdu Seyoum Tarekegn , Mohammed Yesuf Adem , Tsegaw Fentie Kassa

{"title":"In vitro acaricide efficacy evaluation on Ambylomma variegatum and Rhipicephalus (Boophilus) decoloratus ticks infesting cattle in the Gondar Zuria District, Northwest Ethiopia","authors":"Bizuayehu Meskele Tafese , Moges Maru , Zewdu Seyoum Tarekegn , Mohammed Yesuf Adem , Tsegaw Fentie Kassa","doi":"10.1016/j.parepi.2026.e00507","DOIUrl":null,"url":null,"abstract":"<div><div>Ticks are major ectoparasites affecting the health and productivity of livestock in Ethiopia. However, there exists limited information on the current efficacy of widely used acaricides including ivermectin 1% and amitraz 12.5%. Experimental randomized controlled study design was conducted from February 2023 to June 2023 to evaluate in vitro susceptibility of field-collected Amblyomma variegatum (A. variegatum) and Rhipicephalus (Boophilus) decoloratus (R. decoloratus) in cattle in Gondar Zuria District Northwest Ethiopia to ivermectin1% and amitraz 12.5% at varying concentrations. Collected engorged female ticks (n = 540) were exposed to four concentrations of ivermectin 1% (0.00125, 0.005, 0.01, and 0.025%) for 24 h and three level concentrations of amitraz 12.5% (0.0125, 0.025, and 0.05%) for 48 h. Ivermectin 1% produced rapid and concentration-dependent mortality, with maximum efficacy of 96.66% for A. variegatum and 90% for R. decoloratus at the highest dose (0.025%). Similarly, amitraz 12.5% showed strong dose-dependent activity after 48 h, achieving mortality of up to 80.0 and 90% for A. variegatum and R. decoloratus, respectively.</div><div>Two-way ANOVA confirmed that ivermectin 1% concentration, observation time and their interaction significantly affected mean mortality rate of A. variegatum (F = 3.34, P = 0.0184; F = 12.51, P < 0.001; F = 4.94, P < 0.001) and R. decoloratus (F = 21.02, P < 0.001; F = 36.81, P < 0.001; F = 3.45, P = 0.0016), respectively. In addition, amitraz 12.5% concentration and exposure time significantly affected mortality in A. variegatum (F = 26.72, p < 0.001; F = 4.20, p = 0.0129) and R. decoloratus (F = 44.41, p < 0.001; F = 12.82, p < 0.001), although the interaction effect was not significant for A. variegatum (P > 0.05) but was significant for R. decoloratus (P < 0.05). These findings indicate that both acaricides remain effective against adult ticks in the study area, with ivermectin 1% acting more rapidly and amitraz 12.5% demonstrating a clear dose–response relationship. Continued surveillance and integrated tick management are recommended to mitigate the risk of emerging acaricide resistance.</div></div>","PeriodicalId":37873,"journal":{"name":"Parasite Epidemiology and Control","volume":"33 ","pages":"Article e00507"},"PeriodicalIF":2.4000,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Parasite Epidemiology and Control","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2405673126000322","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2026/4/25 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"INFECTIOUS DISEASES","Score":null,"Total":0}

引用次数: 0

Abstract

Ticks are major ectoparasites affecting the health and productivity of livestock in Ethiopia. However, there exists limited information on the current efficacy of widely used acaricides including ivermectin 1% and amitraz 12.5%. Experimental randomized controlled study design was conducted from February 2023 to June 2023 to evaluate in vitro susceptibility of field-collected Amblyomma variegatum (A. variegatum) and Rhipicephalus (Boophilus) decoloratus (R. decoloratus) in cattle in Gondar Zuria District Northwest Ethiopia to ivermectin1% and amitraz 12.5% at varying concentrations. Collected engorged female ticks (n = 540) were exposed to four concentrations of ivermectin 1% (0.00125, 0.005, 0.01, and 0.025%) for 24 h and three level concentrations of amitraz 12.5% (0.0125, 0.025, and 0.05%) for 48 h. Ivermectin 1% produced rapid and concentration-dependent mortality, with maximum efficacy of 96.66% for A. variegatum and 90% for R. decoloratus at the highest dose (0.025%). Similarly, amitraz 12.5% showed strong dose-dependent activity after 48 h, achieving mortality of up to 80.0 and 90% for A. variegatum and R. decoloratus, respectively.

Two-way ANOVA confirmed that ivermectin 1% concentration, observation time and their interaction significantly affected mean mortality rate of A. variegatum (F = 3.34, P = 0.0184; F = 12.51, P < 0.001; F = 4.94, P < 0.001) and R. decoloratus (F = 21.02, P < 0.001; F = 36.81, P < 0.001; F = 3.45, P = 0.0016), respectively. In addition, amitraz 12.5% concentration and exposure time significantly affected mortality in A. variegatum (F = 26.72, p < 0.001; F = 4.20, p = 0.0129) and R. decoloratus (F = 44.41, p < 0.001; F = 12.82, p < 0.001), although the interaction effect was not significant for A. variegatum (P > 0.05) but was significant for R. decoloratus (P < 0.05). These findings indicate that both acaricides remain effective against adult ticks in the study area, with ivermectin 1% acting more rapidly and amitraz 12.5% demonstrating a clear dose–response relationship. Continued surveillance and integrated tick management are recommended to mitigate the risk of emerging acaricide resistance.

查看原文本刊更多论文

体外杀螨剂对埃塞俄比亚西北部贡达尔苏里亚地区牛只间斑绵虫和脱色鼻头蜱的杀螨效果评价

蜱是影响埃塞俄比亚牲畜健康和生产力的主要体外寄生虫。然而，目前广泛使用的杀螨剂（包括1%的伊维菌素和12.5%的阿米特拉斯）的有效性信息有限。于2023年2月至2023年6月，在埃塞俄比亚西北部贡达尔苏里亚区进行了试验随机对照研究设计，以评价田间采集的牛中变异钝瘤（A. variegatum）和脱色鼻头虫（Boophilus）对不同浓度1%伊维菌素和12.5%阿米特兹的体外敏感性。将收集到的540只雌蜱分别暴露于4种浓度为1%的伊维菌素（0.00125、0.005、0.01和0.025%）和3种浓度为12.5%的阿米特拉斯（0.0125、0.025和0.05%）处理24 h和48 h。1%的伊维菌素快速致死且呈浓度依赖性，在最高剂量（0.025%）下，对变异小蠊和脱色小蠊的最高杀伤率分别为96.66%和90%。同样，12.5%的阿米特拉兹在48 h后表现出很强的剂量依赖性活性，对变异田鼠和脱色田鼠的死亡率分别高达80.0和90%。双因素方差分析证实，伊维菌素1%浓度、观察时间及其交互作用分别显著影响变异豚鼠（F = 3.34, P = 0.0184; F = 12.51, P < 0.001; F = 4.94, P < 0.001）和脱色豚鼠（F = 21.02, P < 0.001; F = 36.81, P < 0.001; F = 3.45, P = 0.0016）的平均死亡率。此外，阿米特拉兹12.5%浓度和暴露时间显著影响变异田鼠和脱色田鼠的死亡率（F = 26.72, p < 0.001; F = 4.20, p = 0.0129）和脱色田鼠（F = 44.41, p < 0.001; F = 12.82, p < 0.001），互作效应对变异田鼠不显著（p > 0.05），但对脱色田鼠显著（p < 0.05）。这些发现表明，在研究区域，这两种杀螨剂对成年蜱仍然有效，1%的伊维菌素和12.5%的阿米特拉兹表现出明确的剂量-反应关系。建议继续进行监测和蜱虫综合管理，以减轻新出现的杀螨剂耐药性风险。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Parasite Epidemiology and Control Medicine-Infectious Diseases

CiteScore

5.70

自引率

3.10%

发文量

审稿时长

17 weeks

期刊介绍： Parasite Epidemiology and Control is an Open Access journal. There is an increasing amount of research in the parasitology area that analyses the patterns, causes, and effects of health and disease conditions in defined populations. This epidemiology of parasite infectious diseases is predominantly studied in human populations but also spans other major hosts of parasitic infections and as such this journal will have a broad remit. We will focus on the major areas of epidemiological study including disease etiology, disease surveillance, drug resistance and geographical spread and screening, biomonitoring, and comparisons of treatment effects in clinical trials for both human and other animals. We will also look at the epidemiology and control of vector insects. The journal will also cover the use of geographic information systems (Epi-GIS) for epidemiological surveillance which is a rapidly growing area of research in infectious diseases. Molecular epidemiological approaches are also particularly encouraged.