MODELING INSECT PHENOLOGY USING ORDINAL REGRESSION AND CONTINUATION RATIO MODELS

Two classes of phenology model that can be applied to discrete development stages of insects and estimated from stage frequency data are described. First, ordinal regression models, which assume there is an underlying, unobserved, and continuous variable controlling development level; and second, a class of models based on continuation ratios, which preserves the discrete nature of the development stages, are described. Model estimation and testing based on generalized linear modeling methodology are described using a published data set on the phenology of the western spruce budworm, Choristoneura occidentalis Freeman.