Deterrent(s) in Jack Pine, Pinus banksiana, Influencing Larval Feeding Behavior and Survival of Neodiprion swainei and N. rugifrons1,2

Abstract

Neodiprion swainei Middleton and N. rugifrons Middleton actively reject current season (juvenile) foliage of jack pine, Pinus banksiana Lamb., early in the growing season and their development is aberrant on an exclusively juvenile foliage diet. In bioassay, larval feeding was inhibited by extracts of juvenile foliage. Solvent extracts of higher polarity were most active as antifeedant(s). Antifeedant(s) also occur in mature foliage in lower concentrations. N. rugifrons was more sensitive to the antifeedant(s) than N. swainei. Other sawfly species were slightly deterred or not affected by juvenile foliage extracts: viz. N. nanulus nanulus Schedl, N. taedae linearis Ross, N. pratti paradoxicus Ross, and N. sertifer (Geoffroy). Larvae of N. swainei rejected young juvenile foliage even after it had been extracted in hexane. Bioassay of serial dilutions revealed that antifeedant activity was greatest in the aqueous fraction (AF) (following extraction) and the non-volatile fraction (following distillation) hexane extracts of juvenile foliage. Mature jack pine foliage sprayed with AF inhibited feeding, development, and survival of N. swainei and thus acted as a physiological inhibitor to larvae.