Retained metabolic activity in honey bee collected pollen has implications for pollen digestion and effects on honey bee health
The mechanisms by which pollen is digested by honey bees are incompletely understood. Potential methods are thought to include pseudogermination, mechanical disruption, enzymatic breakdown, or osmotic shock. Understanding the role of pseudogermination in this process has been hampered by a lack of tools demonstrating retention of metabolic activity in pollen collected by honey bees. Here, we show that pollen collected by honey bees produces reactive oxygen species (ROS) at robust levels upon germination, suggesting that ROS is a suitable marker of this process in pollen. ROS can be readily found in the digestive tract of honey bees and is localized to pollen grains within the lumen. Finally, manipulating pollen levels in the midgut can change ROS levels in the digestive tract. These data provide evidence of retained metabolic activity in bee-collected pollen that lends support to pseudogermination as a mechanism for pollen digestion in honey bees, and points to novel approaches for better understanding of pollen digestion in this species and beyond.
Keywordsecology honey bee pollen pollinator digestion
The authors acknowledge Heather Mattila for helpful comments about this study.
MM, SRP, and JWS conceived and designed the experiments. MM, SRP, TRA, and JWS performed experiments and analyzed the data. All authors contributed to the drafting and revision of the article.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Bacsi A, Dharajiya N, Choudhury BK, et al (2005) Effect of pollen-mediated oxidative stress on immediate hypersensitivity reactions and late-phase inflammation in allergic conjunctivitis. J Allergy Clin Immunol 116:836–843. doi: https://doi.org/10.1016/j.jaci.2005.06.002 CrossRefPubMedPubMedCentralGoogle Scholar
- Betts AD (1935) The constancy of the pollen-collecting bee. Journal of Horticultural Science 16:111–113.Google Scholar
- Gilliam M (1997) Identification and roles of non-pathogenic microflora associated with honey bees (vol 155, pg 1, 1997). FEMS Microbiology Letters 157:219–219Google Scholar
- Griggs W, Vansell G, Lwakiri B (1953) Pollen storage: High viability of pollen obtained after storage in home freezer. Calif Agr 7:12Google Scholar
- Singh S, Boynton D (1949) Viability of apple pollen in pollen pellets of honeybees. Proc Am Soc Hort Sc 53:148–153.Google Scholar
- Verhoef H, Hoekstra FA (2012) Absence of 10-hydroxy-2-decenoic acid (10-HDA) in bee-collected pollen. In: Mulcahy DL (ed) Biotechnology and Ecology of Pollen: Proceedings of the International Conference on the Biotechnology and Ecology of Pollen, 9–11 July, 1985, University of …. Springer New York, New York, pp 391–396Google Scholar
- Waser NM, Ollerton J (eds) (2006) Plant-pollinator interactions: From specialization to generalization. Chicago, ILGoogle Scholar
- Winston ML (1987) The Biology of the Honey Bee. Harvard University Press, Cambridge, MAGoogle Scholar
- Wright GA, Nicolson SW, Shafir S (2018) Nutritional Physiology and Ecology of Honey Bees. Annual Review of Entomology 63:327–344. doi: https://doi.org/10.1146/annurev-ento-020117-043423 CrossRefPubMedGoogle Scholar