Insecticide resistance in indoor and outdoor-resting Anopheles gambiae in Northern Ghana
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laria Journal Open Access
RESEARCH
Insecticide resistance in indoor and outdoor‑resting Anopheles gambiae in Northern Ghana Majidah Hamid‑Adiamoh1,2 , Alfred Amambua‑Ngwa1,2, Davis Nwakanma2, Umberto D’Alessandro2, Gordon A. Awandare1 and Yaw A. Afrane1,3*
Abstract Background: Selection pressure from continued exposure to insecticides drives development of insecticide resist‑ ance and changes in resting behaviour of malaria vectors. There is need to understand how resistance drives changes in resting behaviour within vector species. The association between insecticide resistance and resting behaviour of Anopheles gambiae sensu lato (s.l.) in Northern Ghana was examined. Methods: F1 progenies from adult mosquitoes collected indoors and outdoors were exposed to DDT, deltame‑ thrin, malathion and bendiocarb using WHO insecticide susceptibility tests. Insecticide resistance markers including voltage-gated sodium channel (Vgsc)-1014F, Vgsc-1014S, Vgsc-1575Y, glutathione-S-transferase epsilon 2 (GSTe2)-114T and acetylcholinesterase (Ace1)-119S, as well as blood meal sources were investigated using PCR methods. Activities of metabolic enzymes, acetylcholine esterase (AChE), non-specific β-esterases, glutathione-S-transferase (GST) and monooxygenases were measured from unexposed F1 progenies using microplate assays. Results: Susceptibility of Anopheles coluzzii to deltamethrin 24 h post-exposure was significantly higher in indoor (mortality = 5%) than outdoor (mortality = 2.5%) populations (P = 0.02). Mosquitoes were fully susceptible to mala‑ thion (mortality: indoor = 98%, outdoor = 100%). Susceptibility to DDT was significantly higher in outdoor (mortal‑ ity = 9%) than indoor (mortality = 0%) mosquitoes (P = 0.006). Mosquitoes were also found with suspected resistance to bendiocarb but mortality was not statistically different (mortality: indoor = 90%, outdoor = 95%. P = 0.30). Frequen‑ cies of all resistance alleles were higher in F1 outdoor (0.11–0.85) than indoor (0.04–0.65) mosquito populations, while Vgsc-1014F in F 0 An. gambiae sensu stricto (s.s) was significantly associated with outdoor-resting behaviour (P = 0.01). Activities of non-specific β-esterase enzymes were significantly higher in outdoor than indoor mosquitoes (Mean enzyme activity: Outdoor = : 1.70/mg protein; Indoor = 1.35/mg protein. P 150 infective bites/person/year has been documented [36]. Currently, IRS and LLINs are extensively being deployed annually in Northern Ghana but the impact of these measures on the behaviour and insecticide resistance in vector populations remains unclear. This study therefore
Hamid‑Adiamoh et al. Malar J
(2020) 19:314
investigated the association between resting behaviour of members of An. gambiae s.l. and insecticide resistance and its contribution to residual malaria transmission in Northern Ghana.
Methods Study sites
The study was conducted in two rural communities in Northern Ghana, which are 16 km apart, Kpalsogu (9.33° N, 1.02° W) and Libga (9.35° N, 0.51° W) (Fig. 1). Northern Ghana was chosen
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