Low seasonal temperatures promote life cycle synchronization

In this paper we discuss how seasonal temperature variation and life-stage specific developmental thresholds that cause quiescence can synchronize the seasonal development of exothermic organisms. Using a simple aging model i t is shown that minimal seasonal temperatur e variation and periods of quie scence during extreme temperature conditions are sufficient to establish st able, univoltine ovipositional cycles. Quiescence induced by life-stage spe cific developmental thresholds, in fact, promotes synchronous oviposition a nd emergence. The mountain pine beetle, an important insect living in extre me temperature conditions and showing no evidence of diapause, invites dire ct application of this model. Simulations using mountain pine beetle parame ters are used to determine temperature regimes for which stable oviposition al cycles exist. (C) 2001 Society for Mathematical Biology.