Grant: Discovery Launch Supplement

The evolutionary transition from solitary to group living affords many fitness benefits including access to information, foraging efficiency, and anti-predator defences. However, living in groups, particularly large societies of related individuals living in close proximity, brings increased risk of parasite and disease transmission. The long-term goal of my research program is to determine how pathogens and parasites influence social insect behaviour, and how behaviour, in turn affects individual and group health, including behaviour associated with social immunity. My model system for the proposed research is the Western honey bee (Apis mellifera), a eusocial species that is critical for agriculture, but susceptible to many diseases and parasites. The proposed research has three main short-term objectives: (1) To understand how pathogens affect colony productivity through foraging behaviour. This objective will examine the effects of the fungal gut parasite (Vairimorpha) on the foraging behaviour of honey bees. Specifically, it will test whether infection level (high versus low) affects (i) the age at which workers transition from in-hive tasks such as nursing to foraging (ii) their decision whether to forage for pollen (protein) or nectar (carbohydrate), and (iii) whether infection affects the size of load they are able to carry back to nestmates and ultimately the ability of the colony to store resources to survive the winter dearth. (2) To understand the role of genetics in social immunity. This objective will compare the expression of social immunity behaviours in honey bees from different genetic sources and geographical environments, examining which specific sub-behaviours are most effective at preventing or minimising the effects of pathogens in southern Alberta, specifically viruses, trypanosomes, and a fungal pathogen (Vairimorpha). (3) To understand how interactions among group members are structured to minimise the risk of infection to vulnerable group members. This objective will link pathogen load with levels of exposure to vulnerable young and reproductive colony members via social interactions. We will seek to understand the influence of (i) viruses (ii) Vairimorpha gut parasites and (iii) parasitic Varroa mites on the frequency and nature of interactions of adult workers with the queen, drones, and larvae, predicting that individuals posing higher risk should be exposed to these vulnerable society members less than predicted by chance. This research is novel in approach as it will apply behavioural ecology and epidemiological theory to questions of honey bee health. Western honey bees are a critical managed pollinator, and ensuring healthy bees is an important aspect of Canadian agriculture. In addition, insights from the study of social insect behavioural immunity contributes to our understanding of how social interactions influence disease dynamics in all social groups.