Picky eaters: Bumble bees prefer plants with nutrient-rich pollen
Bumble bees have discriminating palettes when it comes to their pollen meals, according to researchers at Penn State. The researchers found that bumble bees can detect the nutritional quality of pollen, and that this ability helps them selectively forage among plant species to optimize their diets.
"Populations of many bee species are in decline across the world, and poor nutrition is thought to be a major factor causing these declines," said Christina Grozinger, director of the Center for Pollinator Research, Penn State. "Our studies can help identify plant species and stocks that provide high-quality nutrition for bumble bees and potentially other bee species, which will help in the development of pollinator-friendly gardens and planting strips."
According to Anthony Vaudo, a graduate student in entomology who led the study, scientists previously believed that bees' preferences for flowering plants were driven by floral traits, such as color, scent, morphology or nectar concentration.
"Here we show that bumble bees actually choose a plant for the nutritional quality of its pollen," said Vaudo. "This is important because pollen is bees' primary source of protein and lipids."
The researchers observed and recorded bumble bees as they foraged for pollen among host-plant species in an outdoor arena where the bees were restricted to only those plants. They then determined the carbohydrate, protein and lipid concentrations, as well as protein-to-lipid ratios (P:L), of the pollen from all the plants within the arena. The team analyzed the relationship between the foraging rates and the nutritional quality of the pollen. They report their results in today's (June 27) issue of the Proceedings of the National Academy of Sciences.
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Bumble Bee Image Christy Stewart via FWS