ABSTRACT
The western honey bee, Apis mellifera L. (Hymenoptera), is arguably the most important pollinator worldwide. While feeding, A. mellifera uses a rapid back-and-forth motion with its brush-like mouthparts to probe pools and films of nectar. Because of the physical forces experienced by the mouthparts during the feeding process, we hypothesized that the mouthparts acquire wear or damage over time, which is paradoxical, because it is the older worker bees that are tasked with foraging for nectar and pollen. Here, we show that the average length of the setae (brush-like structures) on the glossa decreases with honey bee age, particularly when feeding on high-viscosity sucrose solutions. The nectar intake rate, however, remains nearly constant regardless of age or setae length (0.39±0.03 μg s−1 for honey bees fed a 45% sucrose solution and 0.48±0.05 μg s−1 for those fed a 35% sucrose solution). Observations of the feeding process with high-speed video recording revealed that the older honey bees with shorter setae dip nectar at a higher frequency. We propose a liquid transport model to calculate the nectar intake rate, energy intake rate and the power to overcome viscous drag. Theoretical analysis indicates that A. mellifera with shorter glossal setae can compensate both nectar and energy intake rates by increasing dipping frequency. The altered feeding behavior provides insight into how A. mellifera, and perhaps other insects with similar feeding mechanisms, can maintain a consistent fluid uptake rate, despite having damaged mouthparts.
FOOTNOTES
Competing interests
The authors declare no competing or financial interests.
Author contributions
Methodology: Y.C., Y.Y., M.S.L.; Software: C.L.; Validation: Y.C.; Formal analysis: Y.C.; Investigation: C.L., M.S.L.; Resources: S.Y.; Data curation: M.S.L.; Writing - original draft: J.W., M.S.L.; Writing - review & editing: M.S.L.; Supervision: S.Y.; Project administration: J.W., C.L., Y.Y., S.Y.
Funding
This work was supported by research grant from Sun Yat-Sen University for Bairen Plan (contract number 76200-18841223); the National Natural Science Foundation of China (grant no. 51905556); and the Open Project of Henan Key Laboratory of Intelligent Manufacturing of Mechanical Equipment, Zhengzhou University of Light Industry (No. IM201904).
- Received August 16, 2019.
- Accepted October 7, 2019.
- © 2019. Published by The Company of Biologists Ltd
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