Canadian Forest Service Publications

An individual-based phenology model for western spruce budworm (Lepidoptera: Tortricidae). 2013. Nealis,V.G.; Régnière, J. The Canadian Entomologist. 146: 306-320.

Year: 2014

Issued by: Pacific Forestry Centre

Catalog ID: 35439

Language: English

Availability: Order paper copy (free), PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.4039/tce.2013.67

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Mark record


An individual-based phenology model for western spruce budworm, Choristoneura occidentalis Freeman (Lepidoptera: Tortricidae), was developed using stage-specific rates of development, oviposition, and egg hatch observed under controlled conditions at several temperatures. Model output was compared with age distributions estimated by sampling field populations of budworm at several locations in British Columbia, Canada, over many years. The fit of the model was very good for the entire life cycle of the insect. We further validate the model by comparing output with independent observations of moth flight phenology of C. occidentalis and Choristoneura fumiferana (Clemens) in populations of Cypress Hills, Canada and illustrate spatial variation in the seasonal occurrence of early-stage feeding western spruce budworm over most of its range in western Canada. In addition to serving as the underlying structure for the modelling of population dynamics at the seasonal level, the model can be used to predict the time of occurrence of different life stages for precise timing of pest management operations.

Plain Language Summary

The development of insects is determined largely by ambient temperature and so ecological events in the life cycle of insects vary with weather from year to year and place to place. Understanding the effects of weather on an insect’s geographic range and its outbreak behaviour across the landscape requires modelling the interaction between weather/climate and the insect’s seasonal ecology. Our specific model combines careful measurement of development and reproductive rates of individual western spruce budworm with weather records to allow realistic simulation of the insect’s seasonal ecology on Douglas-fir in British Columbia.

A key result is description and validation of a model that sets improved standards for the field. The potential uses of such models are illustrated in this publication by analysis of geographic range of the budworm and estimation of the seasonal timing of protection programs over the entire range of the insect in BC. Future applications of the tool will include analysis of the temporal and spatial distribution of survival to better predict the location of outbreaks and the potential impacts of climate change on geographic range and outbreak behaviour of this insect.