- A new study analyzed pollen from 57 North American plant species to determine which varieties are most nutritionally beneficial to honeybees, which could aid conservation efforts and wildflower restoration projects.
- Based on their findings, the researchers recommend that wildflower restoration projects focus on roses (Rosa sp.), clover (Trifolium sp.), red raspberry (Rubus idaeus), cod vine (Ranunculus acris) and cod vine (Actinidia arguta), stating that the protein-to-lipid ratios in their pollen are ideal for wild bee nutrition.
- Research has shown that honeybees require a diverse diet from multiple plant sources to ensure a balanced intake of fatty acids and essential amino acids, as no single plant species provides optimal nutrition.
- With many bee species facing significant threats, the researchers say they hope their findings can inform conservation efforts, from policy changes to individual actions like planting native flowers and reducing pesticide use.
What’s in a healthy honeybee’s diet? A team of researchers has delved into the world of honeybee nutrition, analyzing pollen to identify the best food sources for this important pollinator. Their findings could have implications for honeybee conservation efforts and pollinator-friendly landscaping.
This study The Frontier of Sustainable Food Systemsanalyzed the nutritional composition of pollen from 57 native North American plant species. Led by Sandra Lehan of York University in Canada, the team looked at levels of essential fatty acids, amino acids, and other key nutrients in the pollen samples.
“Despite high public interest and increasing planting of pollinator plants, little is known about which plant species are best suited for honeybee health,” says Lehan. “This study aimed to gain a better understanding of the nutritional value of plant species.”
Based on their findings, the researchers recommend emphasizing roses.Rosa sp.), clover (Triforium sp.), red raspberry (Raspberry), tall buttercup (Ranunculus acris), Tara vine (Wild pearThe Wildflower Restoration Project has demonstrated the ideal ratio of protein and lipids in pollen for the nutrition of wild bees.
They are tall buttercups (Ranunculus acris) best meets the dietary requirements of honeybees, and hardy kiwi fruit (Wild pear), Ericaceae (Lotus corniculatus), Dogwood (Dogwood), Multiflora Rose (Rosaceae), Red Raspberry (Raspberry), Virginia Rose (Rosaceae), Rose of Sharon (Syrian Hibiscus), Staghorn sumac (Anacardiaceae), European cranberry bush (Viburnum).
When comparing native and exotic plants, we found no significant differences in the overall nutrient content of pollen, suggesting that both native and exotic plants may provide valuable nutritional sources for honeybee populations.
Honeybees depend on two main food sources: nectar and pollen. Nectar provides bees with carbohydrates and moisture, while pollen is their main source of protein, lipids, vitamins and minerals. Adult bees consume both nectar and pollen, with pollen playing an important role in larval development.
When foraging, bees collect pollen using specialized body structures, such as pollen baskets (called corbiculae) on their hind legs or scopal hairs on their abdomen or legs (depending on the species), which they then carry back to their hive or nest.
In social bees like honeybees, worker bees mix pollen with nectar and their own glandular secretions to make “bee bread” to feed to developing larvae. In solitary bees, females feed each larval nest with a mixture of pollen and nectar before laying eggs. This pollen is the only food source for the developing larvae until they reach adulthood. Therefore, the nutritional value of pollen directly impacts the health, development and survival of bee populations.
Honeybees require a diet rich in certain nutrients, especially omega-6 and omega-3 fatty acids. These compounds are essential for honeybees’ longevity, immune function, and ability to cope with environmental stress. However, the balance of these fatty acids is crucial: too much or too little can impair honeybees’ cognitive abilities. In addition, honeybees require essential amino acids for brain health and reproduction. There’s a catch, however: too much of these amino acids can increase their susceptibility to certain parasites. A balanced diet is therefore critical to maintaining honeybee health and vitality.
The study found that to obtain a balanced supply of fatty acids and essential amino acids, honeybees need a diverse diet from multiple plant sources, with no single plant species providing the optimal nutritional profile for pollen.
“There are potential trade-offs between fatty acid and amino acid content in pollen, suggesting that a diverse floral diet may be more beneficial for bees than a single pollen source,” Lehan said. “No single plant species is optimal for the general wild honeybee health.”
In terms of amino acid content, the study found that pollen from almost all plant species contains the 10 essential amino acids required by honeybees, although the content varies greatly between species. Interestingly, pollen from plants in the Asteraceae family (which includes daisies and sunflowers) was particularly rich in essential amino acids. In seven Asteraceae species, the essential amino acid content exceeded 20% of the total pollen content.
The researchers also looked at the protein-to-lipid ratio and the ratio of omega-6 to omega-3 fatty acids in the pollen samples, both of which are thought to be important factors for honeybee nutrition. They found that there was wide variation between species, even within the same plant genus.
“The diversity of pollen nutritional profiles may allow bees, especially specialized species, to selectively forage on resources that best suit their unique dietary requirements,” the study authors note.
The findings are particularly significant given the alarming declines in honeybee populations around the world. With more than 3,600 species of honeybees living in the United States and Canada, honeybees make up an incredibly diverse group of pollinators. However, many bee species face significant threats.
“Around 16 percent of vertebrate pollinators, such as birds and bats, and 40 percent of invertebrate pollinators, such as bees and butterflies, are at risk of extinction,” said a comprehensive report released in May. CABI Review.
Habitat loss and fragmentation, pathogens and disease, pesticides, insecticides such as neonicotinoids, herbicides and fungicides used in agriculture and landscaping, invasive species, climate change, and competition between honeybees and native bees are among the reported causes of pollinator declines.
Loss of preferred host plants has contributed to the decline of some honey bee populations. Additionally, the spread of pests and pathogens poses serious threats to both wild and managed honey bees, and the transportation of managed honey bee colonies for commercial pollination often exacerbates this problem.
The effort to protect honeybees is multifaceted and involves both large-scale policy change and individual actions. At the policy level, efforts include protecting critical habitat, regulating pesticide use, and supporting research into honeybee health.
Groups like the Xerces Society have successfully advocated for federal and state protection of several honey bee species, and they also work with farmers and land managers to implement bee-friendly practices.
Individuals can also play an important role in protecting bees. Planting native flowers, reducing pesticide use, and creating nesting habitat are all effective ways to support local bee populations. Even small actions like turning part of your lawn into a meadow with wildflowers or leaving bare ground for ground-nesting bees can make a big difference.
Lehan and his colleagues say they hope their findings will help inform plant species selection for pollinator gardens and habitat restoration efforts, but they caution that their analysis looked at only 57 plant species out of thousands of species.
“We hope this study will help people choose flowering plants in their gardens for pollinators,” Lehan said, “But we only looked at 57 plant species. We need to look at thousands of plants to understand their nutritional profile. We hope this study will inspire similar studies in the future, as well as follow-up studies on bees’ preferences and survival on different diets.”
Banner Image Photo of sunflowers and bees in Tokyo. Image by mrhayata and available via Flickr (CC BY-SA 2.0).
Liz Kimbrough Mongabay staff writer and graduate from Tulane University with a PhD in ecology and evolutionary biology, where she studied the microbiome of trees. See more of her articles here.
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Quote:
Stephen, KW, Chau, KD, & Rehan, SM (2024). Dietary fundamentals for pollinators: Nutritional profiling of plants for honeybee health. The Frontier of Sustainable Food Systems, 81411410. doi:10.3389/fsufs.2024.1411410
Brunet, J., Fragoso, F.P. (2024). What are the main reasons for the decline of pollinator insect populations around the world? CABI Review, 19(1). doi:10.1079/cabireviews.2024.0016
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