Container emptying alone falls short: mechanical egg removal enhances Aedes aegypti management

Abstract

BACKGROUND: Traditional dengue control efforts focus on eliminating water containers to prevent mosquito breeding, but often overlook Aedes aegypti eggs that remain adhered to container walls. This study compared the effectiveness of two mechanical ovicidal methods—brushing and scrubbing the interior surfaces of containers—against traditional emptying in reducing Ae. aegypti infestation levels. The impact of these methods on non-target dipterans with similar oviposition behavior to the dengue vector was also evaluated; i.e. Clogmia albipunctata (Psychodidae) and Dasyhelea necrophila (Ceratopogonidae). During April 2024, a field trial was conducted on pre-existing black plastic flower vases in a public cemetery from temperate Argentina. RESULTS: Prior to the intervention, out of the 855 containers involved in the study, 765 (89.5%) held water and 351 of such (45.9%) harbored immatures of one or more dipteran species, including Ae. aegypti (observed in 251 containers), C. albipunctata (104), and D. necrophila (51). Both brushing and scrubbing were more effective in reducing the proportion of containers with remaining viable eggs of Ae. aegypti (up to 48.1% and 43.4%, respectively) than just emptying the containers (up to 18.5%). The ovicidal treatments also led to a reduction in the proportion of containers with viable eggs of the non-target dipteran C. albipunctata, but not of D. necrophila. CONCLUSIONS: Mechanical ovicidal methods should be mandatory in container emptying campaigns against Ae. aegypti. These methods should be adapted to the local conditions, aiming to promote more targeted and ecologically safe management strategies.