Insecticide resistance status of Aedes aegypti in Southern and Northern Ghana

Abstract

Background Outbreaks of Aedes-borne arboviral diseases are becoming rampant in Africa. In Ghana, there is no organized arboviral control programme with interventions restricted to mitigate outbreaks. Insecticide application is a crucial part of outbreak responses and future preventative control measures. Thus, knowledge of the resistance status and underlying mechanisms of Aedes populations is required to ensure optimal insecticide choices. The present study assessed the insecticide resistance status of Aedes aegypti populations from southern Ghana (Accra, Tema and Ada Foah) and northern Ghana (Navrongo) respectively. Methods Phenotypic resistance was determined with WHO susceptibility tests using Ae. aegypti collected as larvae and reared into adults. Knockdown resistance (kdr) mutations were detected using allele-specific PCR. Synergist assays were performed with piperonyl butoxide (PBO) to investigate the possible involvement of metabolic mechanisms in resistance phenotypes. Results Resistance to DDT was moderate to high across sites (11.3–75.8%) and for the pyrethroids, deltamethrin and permethrin, moderate resistance was detected (62.5–88.8%). The 1534C kdr and 1016I kdr alleles were common in all sites (0.65 to 1) and may be on a trajectory toward fixation. In addition, a third kdr mutant, V410L, was detected at lower frequencies (0.03 to 0.31). Pre-exposure to PBO significantly increased the susceptibility of Ae. aegypti to deltamethrin and permethrin (P < 0.001). This indicates that in addition to kdr mutants, metabolic enzymes (monooxygenases) may be involved in the resistance phenotypes observed in the Ae. aegypti populations in these sites. Conclusion Insecticide resistance underpinned by multiple mechanisms in Ae. aegypti indicates the need for surveillance to assist in developing appropriate vector control strategies for arboviral disease control in Ghana.

Risk of Arboviral Transmission and Insecticide Resistance Status of Aedes Mosquitoes during a Yellow Fever Outbreak in Ghana

“…This might be due to the indirect impact of the use of insecticides for public health vector control such as the use of Long-Lasting Insecticidal Nets (LLINs) and IRS, as well as pesticide in agriculture (11,42,43). This nding is similar to that reported in a study conducted in Ghana (Abdulai et al, 2023). Whereas Aedes mosquitoes collected from Pagaza and Kpalsogu showed suspected resistance to Permethrin, samples from Larabanga were found to be susceptible to Permethrin.…”

“…Similarly, other studies in Ghana have found high frequencies of V1016I and F1534C kdr mutations in both pyrethroid-susceptible and resistant Aedes mosquitoes collected in Ghana (9,21). This suggests that other resistance mechanism such as metabolic resistance may be involved in insecticide resistance of Aedes aegypti populations in Ghana.…”

“…Yellow Fever is endemic in Ghana; this situation is exacerbated by the limited vaccine coverage, vector abundance and increasing insecticide resistance (9)(10)(11)(12), creating a risk for onward transmission and ampli cation of the virus among unvaccinated populations (10). Major arboviral disease outbreaks have been recorded in Ghana since 1969 (10).…”

“…Increasing insecticide resistance in Aedes mosquitoes poses a major challenge for vector control strategies. Resistance of the Aedes mosquitoes to insecticides has been reported in some West African countries like Senegal, Burkina Faso and Ghana (9,11,17,18). Aedes mosquitoes populations in Ghana have been found to be resistant to several public health insecticides including pyrethroids, organochlorines and carbamates (9,11,12,19).…”

“…Resistance of the Aedes mosquitoes to insecticides has been reported in some West African countries like Senegal, Burkina Faso and Ghana (9,11,17,18). Aedes mosquitoes populations in Ghana have been found to be resistant to several public health insecticides including pyrethroids, organochlorines and carbamates (9,11,12,19). Target-site mutations such as V410L, V1016I and F1534C have been found in pyrethroid-resistant Aedes mosquitoes from Ghana and other countries (9,(20)(21)(22)(23).…”