Stilbenes are naturally occurring in plants, and have been identified as common phytoestrogen compounds. One famous representatives of the stilbene class is resveratrol, a commonly used supplement found in peanuts and grapes. Stilbenes have been considered for their pesticidal effects on insects, mites, and nematodes, but have not yet been evaluated as malaria vector control agent. Fatty acids are produced by animals and plants, and their insecticidal properties have been studied for over a century, but only recently have they been used for mosquito control, as a fatty acid mixture in combination with permethrin.  Here, we screened derivatives of stilbenes and fatty acids for mosquito toxicity on adults, for paralysis on headless larvae, and at the cellular level on <i>Ag</i>Kv2.1 channels. Of the stilbenes tested, only one seemed to yield insecticidal properties, the 2-methoxy stilbene (S943916), on adults and larvae. Fatty acids, including decanoic acid, its derivative 5-hydroxydecanoate (5-HDC), and DAUDA performed poorly in adult toxicity compared to reference compounds (catechol 4-TOC, and carbamate propuxur), but demonstrated an interesting paralytic effect on larvae. This larval effect was consistent with the inhibition of the voltage-gated potassium (Kv) channel. The one hydroxyl group difference made a large impact on the potency for block of the Kv channel activity (Decanoic acid: 0.6 µM; 5-HDC: 30 µM), and yields better inhibition than classic Kv channel blockers, such as tetraethylammonium and 4-aminopyridine. The mode of action of stilbenes and fatty acids is discussed. Additionally, to overcome the adult toxicity issue, we addressed the cuticular permeability of the mosquito by modifying the formulation of the solvent used. By increasing the DMSO concentration to 25% in the solvent, the lethal toxicity of 5-HDC, decanoic acid and DAUDA increased by 2.7-, 4.9- and 18.9-fold, respectively. In conclusion, in the light of the advantages for novel biopesticides fitting the legislative framework for accelerated registration, stilbenes and fatty acids represent interesting leads for mosquito control.

Stilbenes and fatty acids as mosquitocides for control of the malaria vector, <i>Anopheles gambiae</i>

2019 Fall National Meeting

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Stilbenes and fatty acids as mosquitocides for control of the malaria vector, Anopheles gambiae