Physiological relationships between insect diapause and cold tolerance: Coevolution or coincidence?

It is argued that the relationship between diapause and cold tolerance has been obscured by the complexity of these strategies. If cold tolerance is broken down into its component mechanisms a relationship between diapause related metabolic suppression and carbohydrate cryoprotectant synthesis is supported by an increasing number of studies. This link seems to have been overlooked because of the view that temperature is the primary cue for cryoprotectant synthesis. However, some major studies cited in support of the latter view have not rigorously tested the role of diapause. An evolutionary analysis of the relationship suggests that diapause-related carbohydrate synthesis could be a primitive feature within the insects that played an important initial role in their colonisation of colder climates.