Toxicity and context-dependent repellency of temporarily granted repellents under new biocidal products regulations in South Korea against Drosophila melanogaster (Diptera: Drosophilidae)

Abstract

• Repellents for miniscule flying insects is now under legal control in South Korea. • Several compounds were temporarily graced from registration processes. • Contact toxicity and repellent activity of those granted compounds were examined. • Several compounds were either effective or nonactive based on test methods. In South Korea, control agents for small flying insects are subjected to approval under newly enforced Act on biocidal products by the Ministry of Environment starting from 2019, along with other conventional household insecticides. The present study aimed to evaluate 18 compounds for their toxicity and repellency in various contexts. A tube assay revealed the greatest toxicity of synthetic repellent DEET. Interestingly, spatial repellency of several plant essential oils was greater than those of conventional repellent, indicating their suitability for temporal grants. Meanwhile, unlike conventional repellents, botanical oils often lost their choice repellency in gaseous unsaturable condition. Spatial repellency was positively correlated to the evaporation rate of the compounds while choice repellencies were negatively correlated regardless of their gaseous saturability. Our results are expected to provide implications for both the regulation process and product development.