Identification and ecological characterisation ofChoristoneura occidentalis(Lepidoptera: Tortricidae) populations in southwestern Alberta, Canada

Abstract

AbstractThe western spruce budworm,Choristoneura occidentalisFreeman (Lepidoptera: Tortricidae), is an important pest of western North American coniferous forests, where its principal larval host is Rocky Mountain Douglas-fir,Pseudotsuga menziesiisubspeciesglauca(Beissner) Murray (Pinaceae). In southwestern Alberta, Canada, populations were recently discovered feeding on an unconventional host, an Engelmann spruce,Picea engelmanniiParry ex. Engelmann × white spruce,Picea glauca(Moench) Voss hybrid (Pinaceae), in a transition zone between the two major forest types characterised by these conifer species. We use molecular evidence to verify the species identity of outbreakingChoristoneurapopulations collected from Douglas-fir and hybrid spruces in southwestern Alberta in 2009, and characterise the larval and male moth phenology. Both mitochondrial and microsatellite markers confirmed these populations asC. occidentalis, but admixture withChoristoneura fumiferana(Clemens) (Lepidoptera: Tortricidae) was detected in some individuals. Few differences associated with separate host trees were evident in the phenology of larvae and the flight period of male moths.