Nectarivorous insects generally adopt suction or lapping to extract nectar from flowers and it is believed that each species exhibits one specific feeding pattern. In recent literature, large groups of nectarivores are classified as either ‘suction feeders', imbibing nectar through their proboscis, or ‘lappers', using viscous dipping. Honeybees (
Apis mellifera
) are the well-known lappers by virtue of their hairy tongues. Surprisingly, we found that honeybees also employ active suction when feeding on nectar with low viscosity, defying their classification as lappers. Further experiments showed that suction yielded higher uptake rates when ingesting low-concentration nectar, while lapping resulted in faster uptake when ingesting nectar with higher sugar content. We found that the optimal concentration of suction mode in honeybees coincided with the one calculated for other typical suction feeders. Moreover, we found behavioural flexibility in the drinking mode: a bee is able to switch between lapping and suction when offered different nectar concentrations. Such volitional switching in bees can enhance their feeding capabilities, allowing them to efficiently exploit the variety of concentrations presented in floral nectars, enhancing their adaptability to a wide range of energy sources.
Fibrous
surfaces in nature have already exhibited excellent functions
that are normally ascribed to the synergistic effects of special structures
and material properties. The honey bee tongue, foraging liquid food
in nature, has a unique segmented surface covered with dense hairs.
Since honey bees are capable of using their tongue to adapt to possibly
the broadest range of feeding environments to exploit every possible
source of liquids, the surface properties of the tongue, especially
the covering hairs, would likely represent an evolutionary optimization.
In this paper, we show that their tongue hairs are stiff and hydrophobic,
the latter of which is highly unexpected as the structure is designed
for liquid capturing. We found that such hydrophobicity can prevent
those stiff hairs from being adhered to the soft tongue surface, which
could significantly enhance the deformability of the tongue when honey
bees feed at various surfaces and promote their adaptability to different
environments. These findings bridge the relationship between surface
wettability and structural characteristics, which may shed new light
on designing flexible microstructured fiber systems to transport viscous
liquids.
Animals have developed various drinking strategies in capturing liquid to feed or to stay hydrated. In contrast with most animals, honey bees Apis mellifera that capture nectar with their tongue,...
The feeding mechanisms of animals constrain the spectrum of resources that they can exploit profitably. For floral nectar eaters, both corolla depth and nectar properties have marked influence on foraging choices. We report the multiple strategies used by honey bees to efficiently extract nectar at the range of sugar concentrations and corolla depths they face in nature. Honey bees can collect nectar by dipping their hairy tongues or capillary loading when lapping it, or they can attach the tongue to the wall of long corollas and directly suck the nectar along the tongue sides. The honey bee feeding apparatus is unveiled as a multifunctional tool that can switch between lapping and sucking nectar according to the instantaneous ingesting efficiency, which is determined by the interplay of nectar–mouth distance and sugar concentration. These versatile feeding mechanisms allow honey bees to extract nectar efficiently from a wider range of floral resources than previously appreciated and endow them with remarkable adaptability to diverse foraging environments.
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