Host-tree oviposition preference of balsam fir sawfly, Neodiprion abietis (Hymenoptera: Diprionidae), in New Brunswick, Canada

Laboratory experiments using field-collected females were carried out to determine the oviposition preference of the balsam fir sawfly, Neodiprion abietis (Harris) (Hymenoptera: Diprionidae) in New Brunswick, Canada. Unmated adult females given no choice among host-plant foliage laid similar to 98% of available eggs on balsam fir (Abies balsamea (Linnaeus) Miller; Pinaceae), but only 8% and 10%, respectively, on white spruce (Picea glauca (Moench) Voss; Pinaceae) and black spruce (Picea mariana (Miller) Britton, Sterns, and Poggenburg). Given a choice among shoots from all three hosts in the same chamber, unmated females laid all but one egg in balsam fir. Host plant had no effect on female longevity, although there were nearly four-to eightfold more empty egg slits on balsam fir needles, owing presumably to the greater activity of females on this preferred host foliage.