The mosquito, Aedes aegypti (Diptera: Culicidae), is a vector of dengue fever, zika, chikungunya, and yellow fever. The repeated use of synthetic chemical control agents has caused serious insecticide resistance problems. Plant-derived repellents may serve as alternatives in mosquito control as natural products. Four plant-derived mosquito repellents were selected, including citronella oil, 2-undecanone, natural pyrethrum extract, as well as trans-chrysanthemic acid. Studies were performed against a susceptible (Orlando) and a pyrethroid-resistant strain (Puerto Rico) of Aedes aegypti. In the Orlando strain, citronella oil, 2-undecanone, natural pyrethrum extract and trans-chrysanthemic acid showed 1-hr EC50 values for spatial repellency of 33 µg/cm2, 65 µg/cm2, 31 µg/cm2 and 20 µg/cm2, respectively in a high throughput glass tube assay. In the Puerto Rico strain, resistance was observed to natural pyrethrum extract (10-fold), but not to its acid (&lt; 1.9-fold). For 2-undecanone, concentrations of 60-70 µg/cm2 were effective in repelling Orlando females, and higher concentrations were required to repel the Puerto Rico strain. However, levels &gt;100 µg/cm2 were toxic, so an accurate resistance ratio could not be determined. Moreover, trans-chrysanthemic acid showed significant synergistic effects on mosquito repellency when mixed with other compounds. Electrophysiological tests to examine the correlations between behavior and antennal sensitivity to these plant chemical repellents will be discussed. Our results provide insight into the interaction between mosquitoes and plant-derived chemicals and may provide information for understanding collateral effects due to the evolution of insecticide resistance in mosquitoes.

Spatial repellency and antennal responses of Aedes aegypti to plant-derived chemicals

2019 Fall National Meeting

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