Baseline Susceptibility Of Anopheles Gambiae To Clothianidin In Northern Ghana
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Malaria Journal
Abstract
Background: Clothianidin, an insecticide with a novel mode of action, has been deployed in the annual indoor
residual spraying programme in northern Ghana since March 2021. To inform pragmatic management strategies
and guide future studies, baseline data on local Anopheles gambiae sensu lato (s.l.) susceptibility to clothianidin
insecticides were collected in Kpalsogu, a village in the northern region of Ghana.
Methods The phenotypic susceptibility of An. gambiae mosquitoes to clothianidin was assessed using the World Health Organization
Organization (WHO) insecticide resistance monitoring bioassay. The WHO cone bioassays were conducted on mud
and cement walls sprayed with Sumishield 50 wettable granules (WG) (with clothianidin as an active ingredient). Daily
Mortalities were recorded for up to 7 days to observe for delayed mortalities. Polymerase chain reaction (PCR) technique
nique was used to differentiate the sibling species of the An. gambiae complex and also for the detection of knock
down resistance genes (kdr) and the insensitive acetylcholinesterase mutation (ace-1).
Results The WHO susceptibility bioassay revealed a delayed killing effect of clothianidin. Mosquitoes exposed
to the cone bioassays for 5 minutes and died 120 hours after exposure. Slightly higher mortalities were observed in mosquitoes.
toes exposed to clothianidin-treated cement wall surfaces than mosquitoes exposed to mud wall surfaces. The kdr
target-site mutation L1014F occurred at very high frequencies (0.89–0.94) across all vector species identified, whereas
The ace-1 mutation occurred at moderate levels (0.32–0.44). Anopheles gambiae sensu stricto was the most abundant
species observed at 63%, whereas Anopheles arabiensis was the least observed at 9%.
Conclusions Anopheles gambiae s.l. mosquitoes in northern Ghana were susceptible to clothianidin. They harboured
kdr mutations at high frequencies. The ace-1 mutation occurred in moderation. The results of this study confirm
that clothianidin is an effective active ingredient and should be utilized in malaria vector control interventions
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Research Article