Effect of Custard-Apple Oil and Neem Oil on Survival of Nephotettix virescens (Homoptera: Cicadellidae) and on Rice Tungro Virus Transmission1

Abstract

Oils extracted from sceds of custard-apple (Annona squamosa L.) and the Indian neem tree (Azadirachta indica A. Juss) were found to be highly effective in reducing the survival of a leafhopper N. virescens (Distant) and its transmission of the rice tungro virus (RTV). Mean percentages of insect survival on and RTV transmission to plants sprayed with oils at 5, 10, 20, 30, or 50% concentrations were significantly less than for control plants sprayed with water containing 0.1% Teepol liquid detergent. The higher the oil concentration, the lower was the insect survival and RTV transmission; however, after 3 and 2 days, respectively, differences among oil treatments were not significant. The insect failed to survive and transmit RTV to oil-sprayed plants beyond 3 days of exposure, but on control plants, the insect lived for more than 20 days and transmitted RTV up to 5 days. Thus, custard-apple oil and neem oil possess potential for suppression of RTV transmission by the vector.