Canadian Forest Service Publications
Winter mortality and supercooling point of the spruce beetle (Coleoptera: Curculionidae) not affected by host tree vigor in Nova Scotia, Canada. 2012. Rousseau, J.; Bauce, É.; Lavallée, R.; Guertin, C. J. Acad. Entomol. Soc. 8:1-10.
Issued by: Laurentian Forestry Centre
Catalog ID: 33019
CFS Availability: PDF (request by e-mail)
At epidemic levels, the spruce beetle, Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae), is able to spread from moribund to healthy trees by pheromone-mediated mass attacks, allowing insects to access additional, higher-quality food resources. Because host characteristics influence insect performance, we investigated the effect of host vigor on adult spruce beetle overwintering biology in Nova Scotia. Spruce beetles did not produce more cryoprotectants and did not exhibit lower supercooling points or greater winter survival on more vigorous trees. However, they exhibited high cold hardiness, as shown by low supercooling points and mortality rates (around 15%), for all levels of host vigor. Supercooling points reached temperatures as low as -44 °C in January, even though air temperature at the site did not fall below -23 °C. Also, as expected, the insect’s lipid content decreased during the fall period but, surprisingly, was inversely related to tree vigor.