D3034: Mechanisms underlying the efficacy of commonly used insect repellents against Anopheles mosquitoes

The bites from infected female Anopheles mosquitoes lead to hundreds of thousands of deaths annually. To find a human, these mosquitoes rely on their keen sense of smell. Therefore, targeting their olfaction using repellents is an effective way to prevent their attraction to humans and subsequent biting. However, the precise mechanisms underlying the mode of action for most repellents are still unknown. There is evidence that insect repellents function by either targeting mosquito olfactory neurons to actively trigger aversive responses, or masking natural attractant cues emitted by the host. In this study, we use a combination of behavioral assays, calcium imaging, and electrophysiological recordings to determine the specific mechanism by which one commercial repellent outperforms another. This comprehensive approach provides insights into rational development of more effective vector controls. Furthermore, we examine the impact of mosquito age and Plasmodium infection status on repellent efficacy. Understanding the influence of these factors can improve vector control strategies for malaria-endemic regions.