The perils of forcing a generalist to be a specialist: lack of dietary essential amino acids impacts honey bee pollen foraging and colony growth

Abstract

Commercial honey bee colonies pollinate large monocultures, which contain one type of food and thus, one unbalanced source of nutrients. We examined how a lack of dietary essential amino acids (EAAs) affects honey bee foraging behavior and colony growth. Using pollen traps and semi-synthetic diets, we raised bees on three treatments in the field: no diet manipulation, a diet with all 10/10 honey bee EAAs, or a diet with only 6/10 EAAs. In 2016, during a drought, bees raised on the diet lacking EAAs collected more pollen than bees raised with all EAAs, suggesting compensatory foraging. This was not found in 2017, when natural resources were likely more abundant. As such, honey bees lacking EAAs worked harder to fill the gap in the nutrient poor environment. In 2017, colonies raised on all 10 EAAs expanded slower than control colonies, and colonies raised on 6/10 EAAs did not expand at all. This suggests that EAA diversity, and likely other nutrients found in pollen, are essential for colony growth. Forcing this generalist pollinator to be a specialist drastically reduces colony growth and likely, honey bee fitness.

Keywords:

• Apis mellifera
• macronutrients
• nutritional ecology
• pollen supplement
• pollinator health
• protein

Acknowledgements

We would like to thank Joanna Chang, Alexandra Towne, Luke O’Connor, and Adam Winter for helping with data collection and beekeeping, Rick Reault of New England Beekeeping for our bees, Jim Phillips for helping prepare the field site in Grafton, MA, and members of the Starks and Lewis labs for feedback on previous drafts.

Author contributions

REB and PTS conceived and designed this research. REB performed experiments, analyzed data, and wrote the paper; JG helped collect data, and wrote methods sections; PTS aided in data interpretation, and participated in revisions. All authors read and approved the submitted manuscript.

Disclosure statement

No potential conflict of was reported by the authors.

Supplementary material

Supplementary material is available for this article at: https://doi.org/10.1080/00218839.2019.1656702.

Additional information

Funding

This work was supported by the National Science Foundation Research Experience for Undergraduates program at Tufts University [DBI 1560380 to PTS] and the Eastern Apicultural Society (awarded to REB).