The influence of diet on the honeybee lipidome

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Lipids are the substrates of membranes, precursors for hormones, and the means for energy storage in animals. Dietary lipids, such as the polyunsaturated fatty acids linoleic and alpha-linolenic acid, alter the composition of lipid species in an animal's tissues with impacts on animal health, longevity, and fecundity. The impact of dietary lipids on the corporeal lipidome could be greater in insects than mammals, because they cannot synthesize polyunsaturated fatty acids (FAs) or sterols. It is currently unclear how diet modifies an organism's entire lipidome. Honeybees acquire protein, lipids, and micronutrients from floral pollen, but their requirements for dietary fat are poorly characterized. We will test how FAs and sterols in diet affect the entire lipidome of every caste and life history stage in a honeybee colony. We will employ state-of-the art lipidomics to study how specific lipids are incorporated into tissues such as the brain, fat body, and gut. By rearing adult workers in the lab on chemically defined foods previously designed by our team, we will test how FAs affect the regulation of dietary protein, fat, and carbohydrate. Through prior BBSRC funding, we have developed specialized methods for studying whole colony nutrition by feeding small colonies in an enclosed setting with no access to external pollen and nectar. Using this approach, we will also study how the FA composition of food eaten by adult workers affects lipids in the glandular secretions fed to the developing larval workers, queens, and drones. In the field, we will measure how dietary FAs affect the performance of whole colonies with a focus on the foraging worker bee. These data will provide the foundation for studies of the role of fats in bee health and will provide valuable insight towards the importance of dietary fats in the honeybee life cycle, information critical to improving bee welfare.

World agriculture relies on pollinators for food security. In many modern agricultural settings where fruits, vegetables, and nuts are cultivated, pollination is accomplished by honeybee colonies. Plant diversity is usually low in agricultural settings, making it difficult for pollinators to acquire the nutrition they need. Beekeepers now routinely supply honeybee colonies with food to augment the lack of pollen in the landscape. They can purchase food substitutes for pollen, but these substitutes lack essential nutrients. None have been formulated in a way that optimizes combinations of macro- and micronutrients for honeybees. In some cases, they are also made with cheap materials that can cause dysentery.

Unlike other domesticated animals, the nutrition of honeybees has lagged behind. Using information from our basic research on nutrition funded by the BBSRC, we predicted which combination of nutrients would optimize bee performance. These ideas were patented in 2015. By testing many potential substrates, we have created a pollen substitute for honeybee colonies that enhances brood and honey production and reduces Nosema (a gut parasite) load compared to leading commercially-available products. These endeavours, supported by BBSRC responsive mode, an Enterprise fellowship, Follow on Funding, led to the formation of a university spin-out company with the ultimate aim of making foods that improve nutrition for domesticated bees worldwide.

The basic research proposed here will identify the distribution of fats in bee bodies and how fatty acids and sterols in diet influence bee longevity and development. Based on our research, we know that fats are a critical ingredient in any supplementary food that replaces pollen. These experiments will permit us to test many sources of fatty acids that could be added to supplemental foods. An exciting facet of our research will also identify how diet influences the honeybee's glandular secretions (e.g. royal jelly) to affect larval development. The insight gained from these experiments could lead to future innovations in foods designed to optimize queen and drone performance. Our data will also reveal which fatty acid sources and sterols will optimize whole colony performance. In addition, these data could be generalized to identify which plant species' pollen is best for honeybees. This information could be used to inform land managers of which plants are best to cultivate in field margins to improve pollinator welfare in agricultural landscapes.

The data we produce from this work will be protected by intellectual property agreements at our respective universities. We will publish our results in scientific journals and translate our findings for beekeepers through articles in beekeeping magazines, talks at beekeeping conferences, and through our own websites. We expect that the data from our proposal will permit beekeepers to improve upon their methods of feeding and will have a significant, positive impact on pollination services for agricultural crops worldwide.