Chain length influences the repellency of natural aliphatic lactones against Aedes aegypti (Diptera: Culicidae).

Aedes aegypti (L.) is a widely distributed mosquito and the primary vector of arboviruses such as dengue. Its obligatory hematophagy, high environmental adaptability, and close association with humans make it a major public health challenge. Natural repellents with low environmental impact are currently being evaluated in experiments as potential complementary tools for managing Ae. aegypti. The development of environmentally compatible repellents has become a priority in vector control strategies. Lactones are cyclic esters naturally present in various foods and fragrances and have been associated with insect behavioral modulation. Based on these properties, we studied the repellency of natural aliphatic lactones against female Ae. aegypti. Repellency was evaluated using a modified tube-choice bioassay. Lactones differing in side-chain length were tested at 7% and compared with N, N-diethyl-m-toluamide (DEET, 7%) and ethanol as a negative control. Repellency efficacy (ER) was quantified at 5, 10, 30, and 60 min post-exposure. Lactones with 11 and 12 carbons showed little or no repellency (ER60min: 37.6 and 19.5, respectively), whereas γ-hexalactone (C6), γ-octalactone (C8), and γ-nonalactone (C9) achieved ER60min values of 89.7, 83.7, and 74.3, comparable or superior to DEET (ER60min: 72.7). A significant negative correlation was observed between chain length and behavioral repellency (mosquito avoidance). Finding efficient natural repellents is crucial for personal protection plans, especially in areas of the Americas where dengue and other arboviral diseases are expanding.