Redusing winter loss of varroa mite infested honeybee colonies by maximising the size of the winter bee

The mite Varroa jacobsoni represents a major threat to sustained commercial as well as leisure beekeeping in Norway. Infested colonies are much more likely to die during winter than non-infested ones. This seems to be associated with disruption of the dev elopment of the class of physiologically and behaviourally distinguishable long-lived worker bees in late summer and early autumn which normally constitutes the overwintering population. It appears that infested colonies which have developed a substantial amount of winter bees are much less vulnerable to die during winter or early spring. Unfortunately, we are not able today to provide a set of practical procedures maximising the winter bee population in infested colonies. This is because we do not have a clear enough understanding of the main extra- and intra-colonial mechanisms responsible for initiation and maintenance of the physiological and behavioural characteristics of long-lived overwintering bees. This project aims to: 1. Find a non-ambiguous set of physiological and behavioural characteristics distinguishing a winter bee from a summer bee. 2. Use these criteria to study the development and fate of the winter bee population in infested and non-infested colonies. 3. Use computer simulations of the dynamics of the honeybee colony to make mutually exclusice and testable predictions from various hypotheses explaining the cration of winter bees. 4. Teste these predictions to find which explanation is in closest accordance with empirical data. 5. Within a computer simulation framework use the provided information to design a set of management procedures custombuilt for use in Norwegian beekeeping to maximise the winter bee population in infested colonies.