He Zike, Zhang Wei, Sun Yu, Li Chuchu, Wu Jianing, Wu Zhigang
School of Aeronautics and Astronautics, Sun Yat-Sen University, Guangzhou 510006, People's Republic of China.
Functional Morphology & Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany.
J Theor Biol. 2021 Mar 7;512:110538. doi: 10.1016/j.jtbi.2020.110538. Epub 2020 Nov 12.
A honey bee can dip nectar of viscosity across two orders of magnitude, by viscous lapping technique using a segmental tongue covered with erectable hairs. The drinking technique suffers risks of leakage occurring between tongue hairs, and the amount of leakage is related to hair spacing as well as nectar viscosity. When lapping, tongue segments are elongated, which enlarges the hair spacing in longitudinal direction. Experimental observations show that the hair spacing of tongue increases with respect to sucrose solution concentration until it reaches the maximum extension when sucrose solution concentration is above 35%. Considering leakage occurring in the hairy tongue, we hypothesize that the dynamical extension of hair spacing may help honey bees minimize the effects of leakage to reach maximal nectar intake rate. A mathematical model is developed for determining the optimal hair spacing that can meet the demands of both augmenting the nectar intake rate and reducing the risk of leakage. Theoretical prediction and experimental measurements demonstrate honey bees are able to adjust the tongue to meet the optimal hair spacing when dipping nectar of concentration more dilute than 35% and maintain a maximum extension to improve the nectar intake rate when concentration is greater than 35%. We then give the prediction of concentration preferences of three bee species, and discuss effects of dipping frequency and gravity on the leakiness between tongue hairs. This work may not only gain insights into adaptive feeding strategy in insects, but inspire the design of adaptive microfluidic transport devices with dynamic brushy surfaces.
蜜蜂可以通过使用覆盖着可竖起毛发的分节舌头的粘性舔舐技术，蘸取粘度跨越两个数量级的花蜜。这种饮用技术存在舌头毛发之间发生泄漏的风险，泄漏量与毛发间距以及花蜜粘度有关。舔舐时，舌头分节会伸长，这会在纵向扩大毛发间距。实验观察表明，舌头的毛发间距随着蔗糖溶液浓度的增加而增大，直到蔗糖溶液浓度高于35%时达到最大伸长。考虑到有毛舌头会发生泄漏，我们推测毛发间距的动态伸长可能有助于蜜蜂将泄漏的影响降至最低，以达到最大的花蜜摄入率。我们建立了一个数学模型来确定最佳毛发间距，该间距既能满足提高花蜜摄入率的需求，又能降低泄漏风险。理论预测和实验测量表明，当蘸取浓度低于35%的花蜜时，蜜蜂能够调整舌头以达到最佳毛发间距，而当浓度大于35%时，蜜蜂会保持最大伸长以提高花蜜摄入率。然后我们给出了三种蜜蜂物种的浓度偏好预测，并讨论了蘸取频率和重力对舌头毛发间泄漏的影响。这项工作不仅可以深入了解昆虫的适应性进食策略，还能启发具有动态刷毛表面的自适应微流体传输装置的设计。
