Effect of the epicuticular waxes of fruits and vegetables on the photodegradation of rotenone

The effect of epicuticular waxes extracted from fruits (apple, nectarine, pear, and plum) and vegetables (tomato and eggplant) on the photodegradation of rotenone was studied. The waxes affected the decay rate and the degradation pathway of this botanical insecticide. Tomato, nectarine, and plum waxes decreased the photodegradation rate compared to controls, whereas apple and pear waxes increased it. Rotenone irradiated under sunlight without waxes gave seven photoproducts; in contrast, in the presence of waxes it changed its behavior, leading to different pathways according to the wax employed. The main photoproduct formed was 12abeta-rotenolone.