Freezing tolerance and drought resistance of Somatochlora alpestris (Selys) larvae in boreal temporary pools (Anisoptera: Corduliidae)

Larval development of S. alpestris was studied in a semipermanent pond and 2 temporary pools in boreal Sweden. In the pond, several cohorts co-occurred with a life cycle of 3 or 4 years. The temporary pool populations were very small and included only a single larval cohort. The presence of nearly fullgrown larvae after drought periods as long as 3 months documented survival in the dry sediment. As the studied pools freeze solid during winter, the larvae must have survived for about 6 months in ice or frozen sediment. The long larval development of 5. alpestris is unique for insects in temporary pools. It is predicted that the slow larval development characteristic for many odonates, and not the direct mortality from extreme abiotic conditions, limits their success in exploiting this environment.