Beyond insecticides: new thinking on an ancient problem

Key Points Vector-borne diseases are on the rise globally. Although there have been some successes with vaccines and drug treatment, most of the current measures for limiting these diseases focus on vector control. Habitat modification, insecticides, bed nets, biopesticides and sterile-male releases have all been used in the past, with some efficacy. There are also several emerging technologies that rely on genetic modification of the vector or bacterial symbionts for biological control of the vector. Genetic modification approaches include release of insects carrying a dominant lethal (RIDL), homing endonuclease genes (HEGs) and RNAi, with RIDL being the most progressed of these three approaches and currently in the stage of open-field releases. In this approach, mosquito populations are reduced by releasing males carrying a transgene that renders their female offspring flightless. The insect endosymbiont Wolbachia is being developed for control via three potential pathways: releasing male mosquitoes that are mating-incompatible with wild-type female mosquitoes to reduce or eliminate populations, reducing the lifespan of the vector to reduce the number of insects able to transmit the disease, and reducing the ability of a range of pathogens to infect the insect. This latter approach is currently on trial in open-field release studies. The roll out of all these methods will require substantial engagement with all stakeholders to ensure community and government support. Each of the methods harbours risks around long-term stability and the evolution of resistance. These potential drawbacks will only truly be tested by monitoring the efficacy of the approaches following their implementation. As with other interventions, combinations of these approaches with more traditional control practices, such as the use of insecticides, vaccines and drug therapy, might offer the best solution for long-term disease control. In addition to developing vaccines and drugs that target vector-borne diseases, historically the use of insecticides has been the main approach for targeting the vector itself. However, as McGraw and O'Neill describe in this Review, there has been substantial recent progress in developing alternative genetic and biological vector-control strategies. Vector-borne disease is one of the greatest contributors to human mortality and morbidity throughout the tropics. Mosquito-transmitted diseases such as malaria, dengue, yellow fever and filariasis are the m