Biochemical insight into insecticidal properties ofL-Canavanine, a higher plant protective allelochemical

L-Canavanine manifests potent insecticidal properties in a canavanine-sensitive insect such as the tobacco hornworm,Manduca sexta (L.) (Sphingidae). Investigations of the biochemical basis for the antimetabolic properties of this arginine analog reveal that it is activated and aminoacylated by arginyl tRNA synthetase and incorporated into the nascent polypeptide chain. This creates structurally aberrant, canavanine-containing proteins that can possess altered physicochemical properties. Evidence is presented in studies with the tobacco hornworm; the canavanine-adapted bruchid beetle,Caryedes brasiliensis (Bruchidae) and the weevil,Sternechus tuberculatus (Curculionidae); as well as the canavanine-resistant larvae ofHeliothis virescens [Noctuidae] to support the contention that formation of aberrant, canavanyl proteins produce deleterious biological effects and is a significant basis for canavanine's antimetabolic properties.