Canadian Forest Service Publications
Geotaxis and phototaxis are not determinant factors for white pine weevil (Coleoptera: Curculionidae) oviposition location on intact trees and severed treetops. 2004. Manville, J.F.; Sahota, T.S.; Hollmann, J. Journal of Applied Entomology 128(5): 365-368.
Issued by: Pacific Forestry Centre
Catalog ID: 24549
The objective of this investigation was to determine if external factors such as phototaxis and geotaxis determine oviposition site location by reproductively active female white pine weevils, Pissodes strobi (Peck), on intact trees or cut treetops. In prior studies, light and gravity, both external tree factors, were consistently linked with oviposition location. In this study, the external factors that were varied in whole trees or cut treetops, included two weevil populations and two tree species in upright, inverted and horizontal orientations with thick or thin stems, indoor and outdoor locations, warm and cool, wet and dry, and light and dark conditions. The results show that 100% of the oviposition occurred at or near treetops, regardless of external factors. The results are unequivocal; they are without variance. These fndings suggest that the reproductively active female weevil’s feeding preference is for primary cortex tissue, an internal tree factor. The primary cortex thickness gradient could account for these weevils’ capability to locate treetops, where the thickest primary cortex tissue occurs, even when treetops are not at the highest or brightest locations.