Identification of tobacco hornworm antibiosis factor from cuticulae of repandae section ofNicotiana species.

Cuticular components of the green leaves of the Repandae section of theNicotiana species contain compounds that have been shown to be toxic to larvae of the tobacco hornworm larvae,Manduca sexta. The surface constituents of leaves of greenhouse-grownN. repanda, N. stocktonii, andN. nesophila were extracted with methylene chloride in order to isolate the active compounds. Solvent partitioning and gel chromatography was used to isolate a series of hydroxyacylnornicotines (HOAcylNN). The major component was identified asN'-(3-hydroxy-12-methyltridecanoyl)nornicotine. A number of minor 3-hydroxyacylnornicotines, with the acyl group containing C13-C15, were also identified. The HOAcylNN mixture in ethanol was topically applied to first-instar tobacco hornworm larvae at rates of 10, 50, 100, and 200 μg. Mortalities after 48 hr were 33, 44, 78, and 100% respectively.