Exploiting the modes of action of insecticides and acaricides to manage the development of resistance in arthropod pests in Ghana

The importation and use of insecticides and acaricides in agriculture and public health are on the increase in Ghana, while populations of arthropod pests have developed resistance to some active ingredients. However, effective strategies for managing arthropod pest resistance in Ghana are lacking due to the absence of appropriate research for developing effective resistance management strategies. For instance, laboratory studies to evaluate cross-resistance patterns and stability of resistance are not conducted in Ghana. Laboratory studies to determine the mechanisms of resistance to specific active ingredients are also not conducted. In Ghana, resistance research is focused on the detection of esterases in field populations of pests, complemented by resistance ratio which is computed in a wrong manner as the susceptibility of test population divided by the recommended field concentration of active ingredient. Until the right research for developing effective strategies to manage resistance are conducted, the modes of action (MoAs) of active ingredients could be used to help manage resistance development. However, in Ghana, insecticide and acaricide recommendation and their use indicate that the knowledge on exploiting MoAs for resistance management is also lacking. For instance, it is recommended that any of the approved insecticides, imidacloprid, thiamethoxam and bifenthrin, for cocoa mirid control could be used when it is time to spray against mirids. The report that the acaricidal products Cypertop® (contains mixture of cypermethrin and chlorpyrifos), Vetancid® Max (contains mixture of cypermethrin and trichlorfon) and Ectocyp® (contains cypermethrin) were alternated to control ticks also shows the lack of knowledge on exploiting MoAs to manage resistance. This review paper discusses how the MoAs of active ingredients of insecticides and acaricides can be exploited to manage resistance development in arthropod pests in Ghana and the scientific basis of the strategy. Resources for determining the MoAs of active ingredients of insecticides and acaricides are also shared.