Resilience of pollinators in a changing world: impact of developmental environment on metabolism and energetic budgets in social and solitary bees

Project Description

Human activity is simultaneously raising temperatures and changing food resources for beneficial animals, threatening global food security. Although food and temperature individually have well understood effects upon animals, their combined effects are greater than the sum of their parts. Predicting animals' responses requires a systems-level understanding - yet, although theoretical frameworks exist, real-world evaluations of "thermo-nutritional niches" remain scarce. This is a key vulnerability especially for beneficial species imperilled by anthropogenic change, such as pollinators. We are dependent on bees for food security, making forecasting their future vulnerability especially important. Bees are good subjects for our investigations because the growth stage (larvae) are sedentary and completely dependent on food stored by adults, making them tractable for food and temperature manipulations. We use two commercially important bee species with contrasting biologies: honeybees (Apis mellifera) and red mason bees (Osmia bicornis). Honeybees, the most important pollinator species, are highly social, with workers that both provision and thermoregulate their brood. Our second study species, red mason bees, are solitary, do not thermoregulate brood, and are important pollinators of apple orchards. They are chosen to represent the majority of bee species which collectively perform more pollination than honeybees [8] but tend to respond differently to threats [9]. In both species we will (1) map the boundaries of the thermo-nutritional niche for larval development, using 3 major macronutrients (protein, carbohydrate, lipid) and 3 temperatures; (2) evaluate whether adults maintain optimal diets for brood that are experimentally heated under simulated future climate scenarios; and (3) use thermally and nutritionally explicit models to test hypotheses of how honey- and mason bees' contrasting biologies underlie different physiological mechanisms of climate resilience, paving the way for bespoke, targeted management interventions.