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.

Honey bees communicate using many different senses. In past blogs ATTTA has highlighted how these eusocial insects use both smell and sight to communicate and function as a colony: “A Honey Bee’s Perspective: Smell” (Thursday August 10, 2023) and “A Honey Bee’s Perspective: Sight” (Thursday June 22, 2023). Another sense used by honey bees to communicate is sound. Bees perceive sound differently than humans, and we will explore throughout this week’s blog what it means for bees to hear.

A Honey Bee’s Perspective: Sound

Past research indicated the bees seemingly could not hear airborne sound¹. However, it was shown that bees can discriminate between something that is silent and something that produces sound, but only if the sound was intense enough to produce vibrations that were felt by the bees. The vibrational sense organ of the honey bee is the subgenual organ, located in the knee of the bee's leg, which allows bees to perceive the queen’s piping sounds. Substrate borne vibrations are generally perceived by different sensory structures than airborne sounds².  Various studies looked for sensory structures of bees that were suitable for detecting airborne sound, but concluded bees do not hear³. This was accepted until the question was revisited by researchers in 1989⁴.

Airborne sound can be either an oscillation of pressure or an oscillation of the molecules in the air⁵. Humans respond to pressure changes, but other animals, such as honey bees, respond to the oscillation of the air molecules⁵. Early investigations on the sense of hearing in honey bees provided stimuli that could only be perceived as sound pressure changes⁵. A study by Towne and Kirchner used a sound signal of high air particle oscillation as the conditioning stimulus for bees, which provided the first direct evidence for a sense of hearing in bees⁴.

In the mentioned study, bees were trained to fly to a feeder, where two different stimuli could be presented: a sound signal and a mild electric shock. The sound signal was similar to the sound made by a dancing bee in frequency and intensity. It was presented for five seconds. Four seconds after the onset of the sound, the electric shock was delivered. The experiment determined that bees could make use of the sound signal in order to withdraw from the feeder before the onset of the electric shock demonstrating bees can hear airborne sounds.

Interestingly, beekeepers have been conducting a particular practice, known as tanging, to induce flying swarms to settle since the 1800s⁶. Tanging is the act of hitting metal objects together to produce a clanging sound and if the practice is truly effective it would indicate honey bees can hear. Although many question the efficacy of tanging, the practice is still used today. However, current research provides no evidence that tanging causes a flying swarm to settle⁶. While honey bees do communicate using sound, they cannot hear in far-field which relies on detecting changes in air pressure⁷. As indicated, honey bees instead hear in near-field which involves detecting the movement of air particles⁷. Given that bees cannot hear in far-field, it is unlikely that bees in a swarm can detect the sound of tanging.

Knowing that bees can hear, Dreller and Kirchner (1995) investigated the frequency range and sensitivity of honey bee’s sense of hearing. Bees can hear sound of low pitch up to 500 Hz. Humans, in contrast, can perceive sound up to 12 000 - 16 000 Hz.

Given that bees' ears are in fact not pressure sensitive like human ears, but particle-velocity sensitive, bees must use structures which can be bent or deflected by air currents, as is true for hairs or antennae⁵. The study by Dreller and Kirchner (1995) concluded that the hearing structures of bees are located on their antennae. The antenna of the honey bee is a complicated structure, which is also used as the bee’s nose. The part of the antenna responsible for the bee’s hearing ability is located in the distal joint of the pedicel of the antenna, known as the Johnston’s organ⁵. The Johnston’s organ is not unique to honey bees, as it exists in nearly all orders of insects⁸.

Drawing of section of honey bee antennae with Johnston’s organ labeled (Erber et al. 2000)⁹.

Honey bees use their sense of hearing to effectively communicate the location of food sources. This is done in addition to their use of dance to communicate forage location. During the straight component of the waggle dance, dancers emit a sound signal^5,10. The sound has a frequency of about 250 Hz^5,9. Dreller and Kirchner (1995) proved that hearing, in addition to dance communication, is necessary for honey bees to perceive information on forage location. The researchers did this by demonstrating honey bees with one removed antennae recruited less bees to learn forage location, and bees receiving the information ended up taking significantly longer to find the food source. Sound perception by the antennae is necessary for successful dance communication and is required to correctly perceive dance sounds⁵. Therefore, bees use and perceive airborne sounds, which provides information about forage location⁵.

There is still more to learn regarding how honey bees utilize their sense of hearing to effectively communicate and function as a colony. To learn more about how honey bees use their senses to operate as a colony, read our blog on October 31st which will explore the honey bee’s sense of taste.

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. Hansson, A. 1945. Sound production and sound perception ability of bees. Opus-cula Entomologica suppl 6: 1-124
2. Michelsen, A., Kirchner, W.H., Andersen, B.B. and Lindauer, M., 1986. The tooting and quacking vibration signals of honeybee queens: a quantitative analysis. Journal of Comparative Physiology A, 158, pp.605-611.
3. McIndoo, N.E., 1922. The auditory sense of the honey‐bee. Journal of Comparative Neurology, 34(2), pp.173-199.
   
4. Towne, W.F. and Kirchner, W.H., 1989. Hearing in honey bees: detection of air-particle oscillations. Science, 244(4905), pp.686-688.
5. Dreller, C. and Kirchner, W.H., 1995. The sense of hearing in honey bees. Bee World, 76(1), pp.6-17.
6. Hudson, H. 1871. Arresting absconding swarms. The American Bee Journal. 6(12): 281–282.
7. Smith, M.L., 2013. Tanging does not cause flying swarms to settle. Journal of Apicultural Research, 52(5), pp.190-193.
8. Field, L.H. and Matheson, T., 1998. Chordotonal organs of insects. In Advances in insect physiology (Vol. 27, pp. 1-228). Academic Press.
9. Erber, J., Pribbenow, B., Kisch, J. and Faensen, D., 2000. Operant conditioning of antennal muscle activity in the honey bee (Apis mellifera L.). Journal of Comparative Physiology A, 186, pp.557-565.
10. Kirchner, W.H and Towne, W.F. 1994. The sensory basis of the honeybee's dance language. Scientific American. 27

There are multiple forms of communication that honey bees utilize. Like many other animals, honey bees communicate with the use of vibrations and pheromones. But perhaps a more unique form of communication they use is dance. Honey bees have special dances performed by the worker bees that provide information about resources around the hive. Read this week’s blog to learn about the communicative dances honey bees perform.

Do the Waggle Dance 

There are a couple of special dances performed by worker bees to inform the hive about a food source and the location. The most famous of these dances is the waggle dance. Often when performing these dances, the workers provide a sample from the source to other foragers using trophallaxis. The returning forager also carries the smell of pollen and/or nectar, which provides more information about the food source to other bees.

The significance of the waggle dance is for foraging bees to notify other foragers when resources are more than 100 meters away from the hive. To notify, the bee moves in a figure eight pattern. More specifically, it is a straight run in the middle of the pattern with two semi-circle movements on either side. This provides information about the distance and direction of the resource (von Frisch, 1967). The waggle dance also informs bees of the quality of the resource (von Frisch, 1967).

There is also another dance that provides information about resources. The round dance informs bees when a resource is less than 15 meters away from a hive. The bee will dance in a round pattern, which tells other members of the colony that the resource is nearby. The round dance does not provide any information about the exact distance or direction of the resource (Frisch, 1967). However, that information is less essential when the resource is nearby.

There are some sceptics who believe that these dances may have no communication value, and that bees locate sources of food based on the scent left behind from previous foragers (Gadagkar, 1996). While bees can find food based on such odours, past experiments convincingly demonstrate that bees can also find food in the absence of smell. This once again suggests that bees find food based on information communicated through dance or possibly sound (Gadagkar, 1996). It has been suggested that honey bees recruit foragers using buzzing flights. These flights take place close to the resource and is another method bees utilize to locate food (Tautz and Sandeman, 2003).

Given that honey bees can find food sources by only using scent, it brings to question if dance communication provides an advantage to foraging bees. A study done by Okada et al. (2014) determined that colonies of honey bees that use the waggle dance have a significantly greater number of successful visits to food sources than colonies that do not use communication or use random dance communication. The experiment was performed with the use of virtual colonies and provides support that the waggle dance still has value in foraging ability.

Finally, several studies completed in the last decade suggest that human-modified habitats are having an impact on the value of dance language. Human-modified habitats are often characterized by mass-flowering crops that may be easy to find and profitable in spring.  However, once these crops have finished flowering, the environment becomes numerous low-quality foraging sites, and the dance’s value may be diminished (Nürnberger et al. 2017; Couvillon et al. 2014). These types of environments have many discrete foraging locations, but their quality is poor and the cost of recruitment to these sites outweighs the benefits. In summary, human impact may have created environments in which honey bee dance communication is not suited (Price, 2019).

Schematic of honey bee communicative dances (Frisch,1967)

Interestingly, honey bees are the only known group of bees that uses nest-based communication to provide information about food resources (Price and Grüter, 2015). The use of dance to communicate is just one of the reasons that honey bees are a highly productive and organized group.

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
Couvillon, M.J., Fensome, K.A., Quah, S.K., and Schürch, R. 2014. Summertime blues: August foraging leaves honey bees empty-handed. Commun. Integr. Biol.
Frisch, Karl von. 1967. The Dance Language and Orientation of Bees. The Belknap Press of Harvard University Press, Cambridge, Massachusetts, pp. 566.
Gadagkar, R. 1996. The honeybee dance-language controversy. Resonance. 1(1): 63 – 70. doi:10.1007/bf02838860
Nürnberger, F., Steffan-Dewenter, I., and Härtel, S. 2017. Combined effects of waggle dance communication and landscape heterogeneity on nectar and pollen uptake in honey bee colonies. Peer J.
Price, R., Grüter, C. 2015. Why, when and where did honey bee dance communication evolve? Frontiers in Evolution and Ecology.
Price, R. et al. 2019. Honey bees forage more successfully without the “dance language” in challenging environments. Sci. Adv.
Tautz, J. and Sandeman, D.C. 2003. Recruitment of honeybees to non-scented food sources. J. Comp. Physiol. A Neuroethol. Sens. Neural. Behav. Physiol.