284 - New Insecticides, Same Challenge: How to Stay Ahead of Resistance

Abstract: Insecticide resistance has emerged in mosquito populations worldwide, posing a threat to the effectiveness of vector control programs, which remain the cornerstone of efforts to prevent mosquito-borne diseases. Similar challenges occur in agriculture, where insect pests have evolved resistance to nearly every major class of insecticides. Lessons from that field, and others, can help guide how we use insecticides in mosquito control to slow the evolution of resistance and protect available tools. Resistance management strategies (RMS) such as rotations, mixtures, mosaics, and refugia have long been proposed, and in some cases implemented, to slow resistance evolution. However, the evidence base identifying which approaches are most effective remains extremely limited, and operational decisions are often guided by practicality rather than data. Until recently, this limitation was largely theoretical: most mosquito control programs across the world relied on one or two insecticide classes, leaving little opportunity to apply true RMS. However, with the recent introduction of new classes of public health insecticides and mixed-chemistry products, that situation is now changing. In this presentation, I will review theoretical and empirical evidence on RMS as applied to mosquito vectors, drawing on insights from both public health and agricultural pest management. I will discuss the key principles underlying RMS design, summarize what is known about the evolutionary and operational trade-offs of different strategies, and identify the most pressing gaps that limit the evidence-based implementation of RMS. With multiple new chemistries now available, the field stands at a pivotal moment: we have both the opportunity and the responsibility to deploy these tools strategically to ensure their long-term sustainability.