Oviposition Deterrence, Stimulation, and Effect on Clutch Size of Choristoneura (Lepidoptera: Tortricidae) Species by Extract Fractions of Host and Nonhost Foliage

Abstract

Homogenated ethanol extracts of balsam fir, Abies balsamea (L.) Miller, white spruce, Picea glauca (Moench) Voss, and jack pine, Pinus banksiana Lambert, were fractionated sequentially into 4 solvent fractions (hexane, butanol, postbutanol water, and an ethanol extract of the residue). Their effect on oviposition was evaluated in screen cage arenas containing a mated female and filter paper substrate, half of which was treated with extract and the other half with solvent. Tests were conducted mainly against spruce budworm, Choristoneura fumiferana (Clemens) and jack pine budworm, C. pinus Freeman, but some fractions were also evaluated against western spruce budworm, C. occidentalis Freeman. Oviposition by the spruce budworm and jack pine budworm was stimulated by filter paper substrates treated with hexane fractions and uniformly deterred by substrates treated with the postbutanol water fraction of both host and nonhost extracts. Significant deterrent activity also occurred with some butanol extract fractions of the respective nonhosts of these budworm species. Western spruce budworm was deterred by the postbutanol water fraction of 1 of the white spruce extracts. To the best of our knowledge, these results are the first evidence for a lepidopteran oviposition deterrent from coniferous foliage. Clutch size of the spruce budworm was not affected by any of the active fractions from host and nonhost extracts, but clutch size of the jack pine budworm was significantly increased by the stimulating extract fraction of its host and decreased by the deterrent extract fraction of its host.