Laboratory efficacy of a solar-powered spatial repellent device against Anopheles mosquitoes
Spatial repellents represent a promising approach to complement existing malaria vector control interventions by reducing contact between mosquitoes and humans. However, the efficacy of passive spatial repellent devices may be affected by environmental conditions, particularly temperature and airflow, which can influence the release of volatile active ingredients. Active-release devices may provide more consistent delivery of spatial repellent compounds. We investigated the efficacy of a commercially available battery-powered spatial repellent device and a low-power solar-powered device designed for potential use in Africa. Laboratory trials were conducted to evaluate the efficacy of the two spatial repellent devices against Anopheles mosquitoes. Protective efficacy was assessed by comparing mosquito probing on human participants during spatial-repellent and control tests. The effect of the devices on mosquito entry into the test chamber was also assessed. The protective efficacy was 86% with the commercial battery-powered device and 80% with the low-power solar-powered device. A Wilcoxon rank-sum test showed that there was no significant difference between the performance of the two devices in terms of protective efficacy (p = 0.856) or entry inhibition (p = 0.7989). The low-power device could be charged using a small, household-level photovoltaic panel, to provide a potentially practical means of delivering spatial repellents in off-grid settings.