Abstract
BackgroundPyrethroid and organophosphate resistance in the malaria vector Anopheles gambiae has led to the search for not only alternative insecticides, but also repellent chemical compounds. However, little is known about the potential actions of repellents and the cross-resistance risk between insecticide and repellent compounds.MethodsHere we show the action of permethrin, DEET, geraniol, carvacrol, culminaldehyde and cinnamaldehyde against three A. gambiae strains: ‘Kis’ (Kisumu susceptible strain), ‘KdrKis’ (pyrethroid resistant strain) and ‘AcerKis’ (organophosphate resistant strain), the last two differing from the first by a mutation on the kdr and ace1 genes, respectively.ConclusionsResults from the DEET assays show it induced repellency for the resistant KdrKis and AcerKis strains but maintained irritancy for the susceptible strain. More generally, we show resistance genes modify the behavior of An. gambiae, increasing or decreasing the effectiveness of DEET and natural compounds, depending on the mutation. These findings offer a new avenue for research on the target and mechanism of repellent compounds. We discuss these findings in the context of vector control strategies.
Highlights
Pyrethroid and organophosphate resistance in the malaria vector Anopheles gambiae has led to the search for alternative insecticides, and repellent chemical compounds
DEET is a repellent to the A. gambiae resistant strain DEET failed to show any repellency on the susceptible Kisumu strain (Kis) strain at low and high doses but showed significant repellency at high concentration for the pyrethroidresistant strains pyrethroid resistant strain (KdrKis) (29.2%) and OP-resistant strain organophosphate resistant strain (AcerKis) (85.7%), compared with the non-treated control (Table 1, Additional file 1: Figure S1)
The repellent effect was significantly higher on the OPresistant strain AcerKis than on the susceptible strain Kis (15%)
Summary
Pyrethroid and organophosphate resistance in the malaria vector Anopheles gambiae has led to the search for alternative insecticides, and repellent chemical compounds. Pyrethroid and OP resistance have been reported in 27 countries from sub-Saharan Africa, with multiple resistance mechanisms, such as decreased sensitivity of the target protein and increased metabolic detoxification, underscoring the need to find alternatives to these chemical insecticides [2, 7, 9, 21,22,23,24]. Some studies showed that kdr resistance failed to decrease the effectiveness of insecticide-treated nets [26], others reported a fitness advantage for kdrresistant phenotypes [22] that could decrease the efficacy of pyrethroid treated nets [27]
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