Canadian Forest Service Publications
Comparative ecology of conifer-feeding spruce budworms (Lepidoptera: Tortricidae). 2015. Nealis, V.G. The Canadian Entomologist. 25 pages.
Issued by: Pacific Forestry Centre
Catalog ID: 36206
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The comparative ecology of conifer-feeding budworms in the genus Choristoneura Lederer (Lepidoptera: Tortricidae) in Canada is reviewed with emphasis on publications since 1980. Systematics and life history are updated and historical outbreak patterns and their current interpretation summarised. Recent evidence is analysed in the context of ecological interactions among three trophic levels; host plant, budworm herbivore, and natural enemies. The influence of weather and climate are viewed as modulating factors. The population behaviour of budworms is interpreted as the result of tri-trophic interactions that vary at different scales. The result of these multi-scale interactions is that despite shared phylogenetic constraints and common adaptations, different budworm species display different population behaviour because of specific ecological relationships with their respective hosts and natural enemies.
Plain Language Summary
Four closely related species of conifer-feeding budworms; eastern spruce budworm, western spruce budworm, jack pine budworm, and two-year cycle spruce budworm periodically outbreak and cause significant damage to Canada’s softwood forests. There has rarely been a year in the past 50 in either eastern or western Canada when one or more of these species is not in outbreak. Aerial application of pesticides to protect foliage is the common management response. This paper presents a synthetic analysis of the population ecology all budworm species with emphasis on original Canadian research since 1980. I emphasize the important differences and variability in outbreak behavior of each species despite the similarities in their life histories. These differences are the result of the particular ecological relationships between each budworm species and its preferred tree host at several spatial and temporal scales. Interactions among trophic levels (tree, budworms, natural enemies) and the influence of weather are included to provide a comprehensive, up-to-date science context for a new generation of advanced population modelling.