Use of long-lasting insecticide-treated nets (LLIN) is the flagship method of preventing malaria transmission. For many years, the pyrethroid family of insecticides has been the primary treatment for LLINs. These insecticides kill mosquitoes that come into contact with the nets, reducing mosquito populations and lowering transmission rates. However, resistance to pyrethroids has grown, contributing to a rise in malaria cases. The World Health Organization (WHO) recommends developing new insecticides with different modes of action to combat pyrethroid-resistant mosquito strains. In response, Bayer has introduced Fludora® fusion, which combines a pyrethroid (deltamethrin) with a neonicotinoid (clothianidin), despite concerns regarding the latter’s impact on bees. Additionally, AAC’s research has focused on the natural insecticide Nootkatone, shown by the CDC to be effective against mosquitoes and safe for use as it is derived from grapefruits. Nootkatone meets WHO requirements but remains expensive at approximately US$3000 per kilogram.
Vikela™ LLIN is AAC’s answer to this challenge. It incorporates Nootkatone, a natural insecticide derived from grapefruits, alongside a pyrethroid. Nootkatone is widely used as a food flavouring agent, but it also meets the safety and efficacy profile required for LLINs. To enhance effectiveness, Vikela™ also includes piperonyl butoxide (PBO), a non-toxic synergist that blocks mosquito enzymes from degrading pyrethroids. Studies by the Centers for Disease Control and Prevention (CDC) confirm Nootkatone’s effectiveness against mosquitoes, thanks to its distinct mode of action.
We have concluded laboratory studies on Nootkatone in pure form and incorporated in an LLIN fibre. The results indicate that Nootkatone is very effective on highly resistant mosquito species and may be of public health value. There is still a lot of work to be done to get a Nootkatone LLIN on the market but current laboratory results point a very encouraging picture.
A
Graph (A): Efficacy of pure Nootkatone on Anopheles funestus mosquitoes with three levels of pyrethroid resistance. 25 mosquitoes are exposed to varying concentrations of Nootkatone dissolved in piperonyl butoxide applied to an area of 25 cm by 25 cm for minutes and mortality is scored 24 hours after the initial exposure.
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Graph (B): Performance of the Vikela™ 2.0 prototype mosquito net on susceptible Anopheles funestus mosquitoes. 5 mosquitoes are exposed to a 25 cm by 25 cm of the net for 3 minutes and then removed. Knockdown is recorded after 30 minutes post-exposure and mortality 24 hours post-exposure.
