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Dryad

Larvicidal activity of Artemsia capillaris and Setaria palmifolia and Macaranga tanarius extracts against Aedes aegypti (Culicidae)

Abstract

Larvicides are an effective method of vector management to control mosquito-borne diseases such as dengue. Growing awareness of environmental concerns with improperly used synthetic insecticides is driving interest in plant-derived biopesticides, perceived as being safer and to which insects are less likely to evolve resistance. This study examined hexane and ethyl acetate extracts of two plants, Artemisia capillaris and Setaria palmifolia, previously identified as having repellent abilities against a biting midge, for any larvicidal ability against the yellow fever mosquito, Aedes aegypti. Only the hexane extract of Artemisia capillaris had an effect, causing almost immediate knockdown of larvae faster than a Bacillus thuringiensis positive control. At doses above 300 ppm, all or nearly all larvae would die within 24 hours, while at lower doses a percentage would recover even if they appeared moribund. The LC50 and LC90 were calculated as 187.60 and 526.24 ppm at 24 hours and 128.31 and 332.26 ppm at 48 hours, respectively. Future research can focus on developing effective formulations for this larvicide, determining the physiological mechanism behind the knockdown effect, or testing its effects on other insects and other mosquito life stages.