Influence of diet on repellent and feeding-deterrent activity of larval oral exudate in spruce budworms (Lepidoptera : Tortricidae)

A two-choice feeding bioassay was used to investigate the effects of larval source (colony versus wild larvae) and rearing medium (artificial versus f oliar diet) on the feeding-deterrent activity of the oral exudate of the sp ruce budworm and the western spruce budworm, Choristoneura fumiferana (Clem .) and Choristoneura occidentalis Free., respectively. Feeding by both wild and colony larvae was deterred by conspecific oral exudate. Larvae reared on artificial diet responded to exudate from both diet- and foliage-reared larvae, whereas the foliage-reared larvae responded only to exudate from ot her foliage-reared larvae. These results suggest that differences exist bet ween artificial diet- and foliage-reared larvae in the composition of oral exudate, in the concentrations of its biologically active constituents, or in differential sensitivity of diet- and foliage-reared larvae to exudate f rom foliage-reared larvae.