The influence of diet on the honeybee lipidome

点击翻译按钮获取中文摘要

Domesticated honeybees are arguably the most important pollinators in the world. Millions of commercially-managed honeybee colonies pollinate vegetables, soft fruit, nuts and oilseed crops every year, ensuring human food security. Honeybees also make important economic contributions to human welfare through honey, wax, and other products such as royal jelly. In the past 15-20 years, intensive management of honeybee colonies has made them more vulnerable to the global spread of pathogens and parasites. In some settings, bees are exposed to a staggering array of agricultural chemicals including pesticides, fungicides and herbicides. Changes to landscape management have reduced the diversity and abundance of flowering plants throughout the world, with concomitant effects on the food available for bees. To overcome these shortages, beekeepers now routinely feed artificial pollen substitutes with unbalanced nutrition that makes bees susceptible to diseases like dysentery. All of these factors are leading to severe colony losses each year in areas where bees are intensively managed. Nutrition plays a critical role in animal health and welfare. The main source of nutrition of honeybees is floral pollen and nectar. Nectar provides carbohydrates whereas pollen provides protein, fat, and micronutrients. Many studies of bee nutrition have focused on the importance of protein, but few have examined the role of fat. Lipids are important components of cell membranes but are also used as signalling molecules and for energy storage. Animals can synthesize lipids de novo from carbohydrates, but some lipids must be acquired from diet. These lipids include essential fatty acids such as the polyunsaturated fatty acids linoleic and alpha-linolenic acid. Insects, unlike mammals, also require a dietary source of sterols. An important discovery from our team identified that the essential fatty acids found in pollen directly impact the nutrition and behaviour of adult worker honeybees. Bees with the incorrect amount of alpha-linolenic acid (so called 'omega-3') exhibit poor learning abilities. Such diet-induced changes to behaviour could have a serious impact on a bee colony, because foraging bees must learn floral traits to acquire pollen and nectar. The research proposed here is poised to make important discoveries regarding the role of lipids in a honeybee colony. We plan to investigate how natural lipids in the pollen and bee bread consumed by nursing-age worker honeybees are taken up and converted into glandular secretions (e.g. royal jelly) fed to larvae. We will quantify how these lipids are distributed within the tissues of adult and larval bees. Using advanced methods developed in our laboratories and state-of-the-art methods for lipidomic analysis, we will map the transformation of dietary fatty acids and sterols into fat compounds found in bee guts, brains, reproductive organs, fat bodies, and brood food glands. Our research will also identify how fats in diet influence the quality of food given to larvae, and whether diet-induced alterations to fat in larval food affect development. Our ultimate goal will be to test how dietary fats influence the longevity of foragers and whole colony performance in a field setting. With these data, we will advise the beekeeping industry of best practice for the use of fats in substitutes for pollen. Using these data, land managers can also choose plants that provide the correct fatty acid and sterols in pollen for flower strip planting in agroecosystems. For these reasons, our research will lead to the improvement of welfare of domesticated bees. It has the potential to make a significant contribution to the enhancement of global food security through its impact on pollination services.