5. Development of a resistance management strategy for ixodid ticks (Acari: Ixodidae) infesting livestock from market available acaricides in southern Ghana

Abstract

The ixodid ticks (Acari: Ixodidae) are the most important ectoparasites infesting livestock in Ghana, causing direct damage to the animals and spreading diseases. The use of acaricides remains the main method for controlling ticks in Ghana. A recent study in Ghana concluded that using a wide variety of acaricides to control ticks on livestock was dangerous as it could lead to resistance in ticks. While it was observed that acaricides of same chemistry were alternated for tick control. These events indicated that in Ghana there is a lack of knowledge on the importance of and how to exploit variety of acaricides to manage tick resistance when cross-resistance patterns have not yet been established. This paper investigated the variety of acaricides on the market for tick conrtol in Accra, Tema and Kasoa in southern Ghana. The acaricides on the market were then used to develop a strategy for managing acaricide-resistance in ticks on livestock. The variety of market acaricides were determined by surveying veterinary pharmacies. Twenty (20) acaricidal products with 8 active ingredients of 4 chemistries were encountered in the study. The chemical groups were amidines, macrocyclic lactones, organophosphates and pyrethroids. The strategy developed for managing resistance in ticks with the acaricidal products on the market was based on mode of action of the active ingredients. The strategy requires the rotaional use of the acaricidal products in ways that reduces the selection pressure of active ingredients of same chemistry on the target-site in tick populations and as a result retard resistance development.