Pollen foraging preferences in honeybees and their relation to the respective pollen nutrient profiles

Authors: Yokota, Seiji; Seshadri, Arathi; BROECKLING, COREY - Colorado State University

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2024
Publication Date: 7/1/2024
Citation: Yokota, S.C., Seshadri, A.H., Broeckling, C. 2024. Pollen foraging preferences in honeybees and their relation to the respective pollen nutrient profiles. Proceedings of the National Academy of Sciences (PNAS). 14. Article 15028. https://doi.org/10.1038/s41598-024-65569-1.
DOI: https://doi.org/10.1038/s41598-024-65569-1

Interpretive Summary: Honeybees are critical for providing essential pollination services to economically important crops such as almonds and sunflowers in California. While completing pollination in these fields, honeybees face reduced dietary diversity. In this study, we provide bees with a choice of different pollen types in a controlled arena and determine their foraging preferences. We then analyzed the nutrient profiles of the different pollen types to understand the nutritional bases for foraging preference. Foragers chose mixed species pollen from inter-crop plantings and pollen from almond orchards was a significant auxiliary. Although diversity in chemical profiles does not directly relate to plant species diversity, our results suggest that the preference for pollen from mixed species plantings by foraging honeybees adds credence to the importance of diverse floral resources in the habitat. Our study also reiterates the need to better understand honeybee dietary requirements for effective habitat management strategies to enable strong and healthy honeybee colonies for sustainable agriculture production.

Technical Abstract: Honeybees are critical insect pollinators experiencing precipitous declines in managed populations due to pressures associated with agricultural intensification related habitat loss leading to reduced diet diversity. Whereas carbohydrates are primarily sourced from nectar, pollen provides most of the other macronutrients and micronutrients necessary for individual development and colony growth. How monoculture affects the nutritional profile of landscapes and understanding nutritional aspects of forager preferences are important steps to determine the ability of bees to acquire nutritionally complete diets. Using a binary scoring system, we tested preferences of foraging honeybees preconditioned to hive-collected pollen from almond orchards (Prunus amgydalus) or sunflower fields (Helianthus annuus) or mixed species inter-row plantings. We then performed metabolomic analyses of the pollen to elucidate the nutritional content of the different pollen types. Irrespective of preconditioning, bees predominantly chose mixed species pollen from inter-crop plantings, with the pollen from almond orchards coming in as a significant auxiliary. The preferred pollens were chemically diverse and richest in cholesterol, vitamins, and phytochemicals quercetin, kaempferol, coumarin, and quinine, but were not consistently high for essential amino acids and polyunsaturated fatty acids. Although diversity in chemical profiles does not directly relate to plant species diversity, our results suggest that the preference for pollen from mixed species plantings by foraging honeybees adds credence to the importance of diverse floral resources in the habitat. Our study also reiterates the need to better understand honeybee dietary requirements for effective habitat management strategies to enable strong and healthy honeybee colonies for sustainable agriculture production.