Abstract

Rotenone has an effective insecticidal activity. However, the photodegradation of rotenone under sunlight or UV (ultraviolet light) leads to negative effects on its insecticidal activity and persistence. This study examined the photo-protection of rotenone when exposed to UV combinated with various nanoparticles. The remaining concentration of rotenone was analyzed by LC-MS/MS (liquid chromatography-triple quadrupole tandem mass spectrometry) at particular intervals. It indicated that various nanoparticles had different effects and combination with ZnO nanoparticle provided remarkable degree of photo-protection of rotenone in UV radiation. In comparision with ZnO, SiO₂ nanoparticle provided moderate degree of photo-protection of rotenone in UV radiation. In addition, TiO₂, Fe₂O₃ and CuO nanoparticle exerted catalytic degradation effects on rotenone to a certain degree.The combination of rotenone and ZnO nanoparticle(4:1) increased the effciency of mortality to the highest compared with the same concentration of sole rotenone or ZnO nanoparticle treatment alone and their co-toxicity coefficient was 128.63. ZnO nanoparticle has good UV photo-protective properties and insecticidal synergism on rotenone. The application of this proposed method can provide significant and practical guidance for improving the photostability and insecticidal activity of rotenone as well as other biopesticides.

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