The spruce budworm, a potential threat for Norway spruce in eastern Canada?

Abstract

Norway spruce, an exotic tree species in North America, was largely used in reforestation programs in the province of Québec between 1972 and 1990. Several of these plantations are now reaching their commercial maturity and the resurgence of spruce budworm outbreak is a reminder that the potential threat of this damaging defoliator for Norway spruce still remains unknown. We used two life-history traits, pupal weight and overwintered larval (L2) weight, to compare spruce budworm biological performance on Norway spruce, white spruce and black spruce. Pupae collected on Norway spruce and overwintered larvae produced by parents that fed on Norway spruce were heavier than those coming from black spruce. Spruce budworm performance was similar on Norway and white spruce, showing similar suitability and suggesting that it can represent a potential threat for Norway spruce plantations established after the last spruce budworm outbreak in eastern North America.