Resistance of ticks on cattle to amitraz in Zimbabwe

Acaricide resistance status of livestock ticks from East and West Africa and in vivo efficacy of acaricides to control them

“…Although there is limited data on the resistance of Amblyomma spp., reports from Zambia ( Muyobela et al, 2015 ) on A . variegatum and from Zimbabwe ( Makuvadze et al, 2020 ) on A. hebraeum presented LC 50 values ranging from 0.009 to 0.02 %, considerably lower than the range of 0.8–2% as found in our LPT results. Makuvadze et al (2020) also noted that their R. appendiculatus reference isolate was three times more sensitive than a reference A. hebraeum.…”

“…variegatum and from Zimbabwe ( Makuvadze et al, 2020 ) on A. hebraeum presented LC 50 values ranging from 0.009 to 0.02 %, considerably lower than the range of 0.8–2% as found in our LPT results. Makuvadze et al (2020) also noted that their R. appendiculatus reference isolate was three times more sensitive than a reference A. hebraeum. The differences in observed tick tolerance to acaricides between in vitro assays and assessments in the target animals further reflect the challenges of interpreting in vitro data into in vivo protection.…”

“…This may relate to the relative lack of usage of these two chemicals as livestock acaricides in this region, the former due to its long withdrawal period and the latter due to cost and lack of efficacy in controlling tsetse flies ( Githaka et al, 2022 ). Whilst the applied LPT methodology, based on the 2004 FAO guidelines, is oriented towards one-host ticks, validation of results for multi-host ticks was based on obtaining a full dose response curve, thus permitting the calculation of representative LC50 values, similar to previously reported approaches ( Chitombo et al, 2021 ; Makuvadze et al, 2020 ). Furthermore, although isoxazolines are known to act primarily systemically, a dose response to topical exposure with fluralaner was observed, providing an indication of susceptibility to this class.…”

Short communication: Potential causes of Acaricide Resistance in Rhipicephalus and Amblyomma Ticks (Acari: Ixodidae) in Namwala District, Zambia

“…Our study adds to the growing knowledge of amitraz resistance in the country, with previous reports indicating presence of resistance in the northern part of the Country (Muyobela et al, 2015). Amitraz resistance in ticks has also been documented across the world (Abbas et al, 2014;Rodríguez-Hidalgo et al, 2017;Rodriguez-Vivas et al, 2018;Makuvadze et al, 2020). Whilst resistance to synthetic pyrethroids is widespread in most parts of the world (Abbas et al 2014: Klafke et al, 2017, this is the rst time, resistance to cypermethrin is being reported in Zambia.…”

Spatio‐temporal variation in tick community composition and abundance in a wildlife–livestock interface within Nyanga National Park, Zimbabwe

“…The effective use of acaricides has not been impactful probably due to inconsistent use, overdilution and poor rotation of the chemicals. Furthermore, acaricide resistance continues to be a formidable challenge towards the effective control of ticks in Zimbabwe (Gono et al, 2014; Makuvaze et al, 2020; Sungirai et al, 2018), thereby compounding tick‐borne disease transmission dynamics at wildlife–livestock interfaces. It has however been observed elsewhere that acaricide‐treated cattle can reduce environmental tick abundance in livestock–wildlife integrated areas (Allan et al, 2017; Keesing et al, 2013; Keesing, Ostfeld, Okanga, et al, 2018; Keesing, Ostfeld, Young, et al, 2018).…”