Novel Sucrose Esters from Nicotiana gossei: Effective Biorationals Against Selected Horticultural Insect Pests

Abstract

Leaf-surface extracts of Nicotiana gossei Domin, N. benthamiana Domin, and N. bigelovii (Torrey) Watson were the most active of those from 17 species of Nicotiana evaluated against late second/early third instars of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Four chromatographically purified sucrose esters of N. gossei resulted in 88-94% mortality of late second/early third instars of the sweetpotato whitefly, Bemisia tabaci (Gennadius). A less purified mixture of the four compounds was effective at 1.0 mg/ml (wt:vol) against nymphs of both whitefly species and the green peach aphid, Myzus persicae (Sulzer), and it deterred feeding and oviposition by the twospotted spider mite, Tetranychus urlicae Koch. These sucrose esters were not active against whitefly eggs; neonates of the Colorado potato beetle, Leptinotarsa decemlineata (Say); or second instars of the western flower thrips, Frankliniella occidentalis (Pergande). The selective activity against immature insects, and the feeding and ovipositional deterrence to spider mites suggest pesticidal activity. Activity of 1.0 mglml (wt:vol) aqueous mixtures of the four compounds was comparable with, or better than, label rates of currently available biorational products or pesticides. The purified product was stable for 1 yr.