New strategies to control malaria amid rising insecticide resistance

Malaria is an infectious disease still prevalent in sub-Saharan Africa as well as parts of Southeast Asia and South America. Insecticide-based measures, such as chemically treated nets and indoor spraying using a group of insecticides known as pyrethroids, have been highly effective - averting an estimated 600 million malaria cases between 2000 and 2015. 

However, mosquitoes, notably Anopheles gambiae, that carry the malaria parasite, are increasingly resistant to pyrethroids, so alternative insecticides with different modes of action are being explored. In 2017, neonicotinoid insecticides were pre-approved for use in malaria control by the World Health Organisation (WHO) and commercial products containing the neonicotinoid clothianidin, are currently in trials. The new findings published in Open Biology, reveal how neonicotinoids affect malaria-carrying mosquitoes, paving the way for new disease-control strategies. 

The study was undertaken by an international team of researchers, with key participants from UCL, Kindai University, Osaka University, Okayama University in Japan, and The Liverpool School of Tropical Medicine. The study is the first to identify a group of neuroreceptors in malaria-carrying mosquitoes (Anopheles gambiae) that are targeted by neonicotinoid insecticides. It also identifies which parts of these receptors can change how well these insecticides work. The neonicotinoids clothianidin and dinotefuran interact with these receptors in unique ways, suggesting possible roles in insect control. Professor Matsuda (Nara, Japan) and Professor David Sattelle (UCL, UK) note that “clothianidin and perhaps dinotefurun could have important roles to play in the control of malaria, particularly in regions facing pyrethroid insecticide resistance.”

The authors are aware that in the long-term, resistance to neonicotinoids is almost inevitable and are already investigating the potential of other chemicals active on receptors distinct from those activated by neonicotinoids. A new affordable vaccine is also being introduced that may lead to reduced malaria prevalence. Similarly, genetic control measures are close to being trialled to supress Anopheles gambiae populations, but new insecticides remain critical, providing immediately-acting tools to assist in integrated malaria control strategies.

Further information

• Research paper: Unravelling nicotinic receptor and ligand features underlying neonicotinoid knockdown actions on the malaria vector mosquito Anopheles gambiae. Open Biology
• Prof David Sattelle academic profile
• Kindai Univesity, Japan
• Main image: Mosquito resting on grass, AdobeStock