Qualitative analyses of larval oral exudate from eastern and western spruce budworms (Lepidoptera: Tortricidae)

L. M. Poirier, J. H. Borden


A two-choice feeding bioassay was used to investigate the effects of dilution, centrifugation, storage and autoclaving on the repellency of the oral exudate of eastern and western spruce budworms, Choristoneura fumiferana (Clem.) and C. occidentalis Free., to their respective conspecifics. The exudate from insects reared on either artificial diet or foliage was active at a volume equal to the amount emitted by one larva when disturbed with a pipet in the laboratory, but repellency was lost at lower doses. Centrifugation did not partition the exudate into active and inactive fractions. Exudate from both diet- and foliage-reared insects was active for at least 48 h at room temperature. However, after being frozen for one month, exudate from diet-reared insects was still active, while that from foliage-reared insects was not.

Key words: Choristoneura fumiferana; Choristoneura occidentalis; spruce budworm; oral exudate; regurgitant; epideictic pheromone

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