Knockdown of Fruit Flies by Imidacloprid Nanoaerosol

This report describes the effects of nanoaerosol particles (NAPs) from imidacloprid (IMI) on fruit flies. NAPs were produced using a newly developed generator which employs electro-hydrodynamic atomization of IMI solution in ethanol. Exposure of Drosophila melanogaster to the IMI NAPs at a concentration of C = 2.7 ± 0.1 ng/cm(3) caused knockdown in half of the flies in T50 = 88 ± 14 min at 22 °C and in T50 = 36 ± 2 min at 33 °C. A number of special experiments precluded IMI volatilization and contact or oral action of IMI upon exposure to the NAPs. It was shown that only the fraction of NAPs in the size range of 7-300 nm is responsible for the knockdown and that dependence of T50 on the NAPs' fraction mass follows Haber's rule, C × T50 = const. Comparison with the oral doses obtained when flies were fed an IMI-sucrose mixture revealed that the inhaled doses that caused knockdown were 2 orders of magnitude lower than the oral ones. This new technology may be used to quickly eliminate insects with nanoaerosols of nonvolatile insecticides in greenhouses and other closed environments.