A MULTIPLE-COHORT MODEL FOR SIMULATING JACK PINE BUDWORM (LEPIDOPTERA: TORTRICIDAE) DEVELOPMENT UNDER VARIABLE TEMPERATURE CONDITIONS

Abstract

AbstractA phenology model for jack pine budworm, Choristoneura pinus pinus Freeman, is presented. Linear and nonlinear relationships between temperature and the development of overwintering larvae, instars 2–7, and pupae are determined, as is variation in the development of each instar. The model uses as input daily maximum and minimum temperatures corrected for the effects of bark and bud microclimate and simulates the number of insects in each instar on a given calendar date. Variation in development of all stages is included. Simulations matched observed data well for north-central and northwestern Ontario in 1986, but overestimated time of development for northwestern Ontario in 1987. Simulations under low, medium, and high temperature conditions revealed that a nonlinear equation for rate of development was necessary for simulating emergence whereas linear rate equations were adequate for simulating development of the feeding instars. The combined effect of bud and bark microclimate on model performance was equal to that which resulted from the use of nonlinear developmental equations.