TITLE:
Spatial Distribution of Tick Acaricide Resistance in Uganda: A Focus on Rhipicephalus appendiculatus and Rhipicephalus decoloratus Tick Species
AUTHORS:
Joseph Byaruhanga, Patrick Vudriko, Benedicto Byamukama, Fred Odua, Yvette Ssebunya, Rashid Kassim Njalira, Christine Nabbale, Sharon Amita, Martin Angwe, Saviour Dralabu, Maria Agnes Tumwebaze, Dickson Stuart Tayebwa, Anthony Mugisha
KEYWORDS:
Ticks, Rhipecephalus appendiculatus, Rhipecephalus decoloratus, Acaricides, Tick Resistance, Uganda, Spatial Distribution, Map
JOURNAL NAME:
Open Journal of Veterinary Medicine,
Vol.15 No.4,
April
25,
2025
ABSTRACT: Acaricide use remains a key intervention for the control of ticks in the tropical countries such as Uganda. However, the use of acaricides for tick control has recently been complicated by the emergence of acaricide resistance. This study provides an update on spatial distribution of acaricide resistance in Rhipicephalus appendiculatus and Rhipicephalus decoloratus ticks in Uganda. A country-wide cross-sectional study in which cattle ticks were collected from 37 districts representing the major regions of Uganda was conducted. A total of 201 tick populations were tested against discriminating concentration of deltamethrin (0.05 mg/ml), amitraz (0.25 mg/ml) and a combination of chlorpyrifos and cypermethrin (0.5/0.05 mg/ml) following FAO’s larval packet test (LPT) method. The resultant acaricide susceptibility data was used to generate acaricide resistance maps with ArcGIS software for desktops version 10.8. Generally, both tick species showed highest acaricide resistance against deltamethrin, followed by amitraz and combination of chlorpyrifos and cypermethrin, at 80.1%, 57.7% and 52.2%, respectively, across tick populations sampled in all regions of Uganda. Multiple acaricide-resistant (resistance to at least two classes of acaricide) R. appendiculatus and R. decoloratus tick populations were widely distributed in the Central, Western and Southwestern regions of Uganda. However, both tick species from the Eastern and Northern regions of Uganda were largely susceptible to the acaricide classes tested. However, the combination of chlorpyrifos and cypermethrin had a better combined effect on Rhipicephalus ticks collected from the Central, Western and Southwestern regions of Uganda. This study confirmed that both single and multiple acaricide resistance by R. appendiculatous and R. decoloratus against deltamethrin, amitraz and combination of chlorpyrifos and cypermethrin was widely distributed across the central, southwestern and western cattle corridor of Uganda. We propose the strengthening of national capacity for the surveillance of tick acaricide resistance at the regional and national levels. The competent authority may consider developing a national acaricide zoning and rotation plan to promote the sustainable use of chemical acaricides for the control of ticks in the country. Implementing strict animal movement control could also reduce the spread of acaricide-resistant ticks in the country.