Continuing with the series “A Honey Bee’s Perspective” this week’s blog will focus on the honey bee’s sense of taste. Taste is important for honey bees when it comes to choosing food and water sources, and for recognizing nestmates¹. This week’s blog will explore the biology of taste of the honey bee, indicating what researchers already understand about their sense of taste, but also highlighting the various aspects that need further investigation.

A Honey Bee’s Perspective: Taste

Prior to discussing how honey bee’s perceive taste, it is important to understand exactly what taste is. Taste is the sense that distinguishes between chemical compounds and the sensations chemical compounds produce based on contact with chemoreceptors¹. A sense of taste allows animals to discriminate edible from nonedible things¹.

In honey bees, the main chemosensory organs are located in the antennae, mouthparts and forelegs². Within these various structures gustatory receptor cells are located within specialized cuticular structures called sensilla³. Gustatory sensilla take the form of hairs or pegs⁴. Gustatory sensilla have a characteristic aperture at the apex through which gustatory substances can penetrate after contacting the hair or peg. Each taste receptor neuron branches up the hair or peg and allows the receptor to bind with specific chemicals depending on their molecular structure⁵. Then the gustatory receptor cells convey the message to postsynaptic neurons by means of acetylcholine⁶.

In 1934, von Frisch found honey bees to only be responsive to seven tested sugars, which included: sucrose, glucose, fructose, melezitose, trehalose, maltose and α-methyl glucoside⁷. Sucrose, glucose and fructose are all found in nectar, and melezitose and trehalose are found in honeydew⁷. Von Frisch also found that gustatory receptors located on the mouthparts (rather than the antennae or forelegs) were responsible for the specificity of responses to these sugars⁷.

Honey bee consuming honey (Perennia©2018).

Haupt (2004) found that the receptors in the antennae of honey bees are sensitive to sucrose stimulation⁸. Their sensitivity is higher than that of receptors on the proboscis⁹. This high sensitivity highlights the role of antennal gustatory receptors in locating a potential food source⁸. Interestingly, bees within the same hive may drastically differ in their sucrose sensitivity¹⁰. As mentioned, taste receptors are also located on the forelegs of honey bees. These receptors can also respond to sucrose but are much less sensitive than receptors within the antennae^11,12.

A total of 10 distinct types of gustatory receptors have been identified within the honey bee genome. However, only 2 of the 10 have been identified to respond to tested sugars, and the other 8 receptors specificity remains to be determined¹³. An explanation to account for such a limited number of gustatory receptor types is that bees have little need for gustatory receptors to locate and recognize food since flowering plants have evolved mechanisms to attract and reward bees for pollination services¹⁴. It is also uncertain if there are only 10 receptor types as each gene that codes for the different receptors can potentially encode for more than 1 receptor type, but this is yet to be proven⁷.

Researchers have been investigating whether honey bees can perceive bitter tasting plants. There are numerous plants that contain alkaloids (bitter tasting compounds to humans) that depend on bees for pollination, such as tobacco plants (Nicotiana sp.), various citrus plants (Citrus spp.) and almond plants (Amygdalus spp.)¹⁵. Interestingly, concentrations of these deterrent alkaloid compounds are low in concentrations in nectar and pollen¹⁶. Researchers have found that nectars containing low concentrations of alkaloids are attractive to bees, even when alternative nectar sources are available, but if concentrations of alkaloids are too high bees are deterred from the nectar^17,18.

A sense of taste plays a vital role in a honey bee’s life. In the context of foraging, honey bees collect nectar and pollen that provides them with nutrition. Given that nectar contains not only different types of sugars, but it also contains organic acids, lipids, minerals, vitamins and aromatic compounds, research indicates honey bees can taste these various compounds to select optimal food¹⁹. Besides foraging for nectar and pollen, bees collect water, and research indicates bees can taste various salts within water. Additionally, bees may rely on both olfaction and taste to recognize members of their hive based on their cuticular hydrocarbons which provide a chemical signature allowing nestmate recognition²⁰.

If you are interested in learning more about honey bee communication, and their senses, be sure to check out past blogs in this series.

Connecting with ATTTA Specialists

If you’d like to connect with ATTTA specialists or learn more about our program, you can:

visit our website at https://www.perennia.ca/portfolio-items/honey-bees/

Email abyers@perennia.ca

References

1. de Brito Sanchez, M.G., 2011. Taste perception in honey bees. Chemical senses, 36(8), pp.675-692.
2. Goodman, L., 2003. Form and function in the honey bee (pp. xii+-220).
3. Briant, T.J., 1884. On the Anatomy and Functions of the Tongue of the Honey-Bee (Worker). Zoological Journal of the Linnean Society, 17(103), pp.408-417.
4. Esslen, J. and Kaissling, K.E., 1976. Zahl und Verteilung antennaler Sensillen bei der Honigbiene (Apis mellifera L.). Zoomorphologie, 83(3), pp.227-251.
5. Clyne, P.J., Warr, C.G. and Carlson, J.R., 2000. Candidate taste receptors in Drosophila. Science, 287(5459), pp.1830-1834.
6. Python, F. and Stocker, R.F., 2002. Immunoreactivity against choline acetyltransferase, γ‐aminobutyric acid, histamine, octopamine, and serotonin in the larval chemosensory system of Drosophila melanogaster. Journal of Comparative Neurology, 453(2), pp.157-167.
7. v. Frisch, K., 1934. Über den Geschmackssinn der Biene: ein Beitrag zur vergleichenden Physiologie des Geschmacks. Zeitschrift für vergleichende Physiologie, 21(1), pp.1-156.
8. Haupt, S.S., 2007. Central gustatory projections and side-specificity of operant antennal muscle conditioning in the honeybee. Journal of Comparative Physiology A, 193(5), pp.523-535.
9. Whitehead, A.T., 1978. Electrophysiological response of honey bee labial palp contact chemoreceptors to sugars and electrolytes. Physiological Entomology, 3(3), pp.241-248.
10. Page Jr, R.E., Scheiner, R., Erber, J. and Amdam, G.V., 2006. The development and evolution of division of labor and foraging specialization in a social insect (Apis mellifera L.). Current topics in developmental biology, 74, pp.253-286.
11. Marshall, J., 1935. On the sensitivity of the chemoreceptors on the antenna and fore-tarsus of the honey-bee, Apis mellifera L. Journal of Experimental Biology, 12(1), pp.17-26.
12. de Brito Sanchez, M.G., Chen, C., Li, J., Liu, F., Gauthier, M. and Giurfa, M., 2008. Behavioral studies on tarsal gustation in honeybees: sucrose responsiveness and sucrose-mediated olfactory conditioning. Journal of Comparative Physiology A, 194, pp.861-869.
13. Chyb, S., Dahanukar, A., Wickens, A. and Carlson, J.R., 2003. Drosophila Gr5a encodes a taste receptor tuned to trehalose. Proceedings of the National Academy of Sciences, 100(suppl_2), pp.14526-14530.
14. Robertson, H.M. and Wanner, K.W., 2006. The chemoreceptor superfamily in the honey bee, Apis mellifera: expansion of the odorant, but not gustatory, receptor family. Genome research, 16(11), pp.1395-1403.
15. Detzel, A. and Wink, M., 1993. Attraction, deterrence or intoxication of bees (Apis mellifera) by plant allelochemicals. Chemoecology, 4, pp.8-18.
16. London-Shafir, I., Shafir, S. and Eisikowitch, D., 2003. Amygdalin in almond nectar and pollen–facts and possible roles. Plant Systematics and Evolution, 238, pp.87-95.
17. Liu, F.L., Zhang, X.W., Chai, J.P. and Yang, D.R., 2006. Pollen phenolics and regulation of pollen foraging in honeybee colony. Behavioral ecology and sociobiology, 59, pp.582-588.
18. Singaravelan, N., Nee'man, G., Inbar, M. and Izhaki, I., 2005. Feeding responses of free-flying honeybees to secondary compounds mimicking floral nectars. Journal of chemical ecology, 31, pp.2791-2804.
19. Harborne, J.B., 2014. Introduction to ecological biochemistry. Academic press.
20. Châline, N., Sandoz, J.C., Martin, S.J., Ratnieks, F.L. and Jones, G.R., 2005. Learning and discrimination of individual cuticular hydrocarbons by honeybees (Apis mellifera). Chemical Senses, 30(4), pp.327-335.