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James Nieh e-mail: jnieh@ucsd.edu |
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Evolution of animal communication: functionally referential communication in social bees
Insect societies have evolved communication systems of remarkable complexity. Highly social bees (honeybees and stingless bees) use sophisticated methods to exploit resources such as pollen, nectar, water, resin and nest sites. Social bees can recruit, increase the number of nestmates at a particular location or increase the number of nestmates searching for a particular resource at non-specific locations. We focus on three closely-related groups: honey bee, stingless bees, and bumble bees.
Stingless bee (Trigona hyalinata) recruiting to homopteran honeydew.
Research in the Nieh lab examines the mechanisms that allow highly social bees to communicate resource location and seeks to understand how these communication systems have evolved and what selective pressures have driven the evolution of bee communication. Recruiting foragers exploit several different information channels - sound, odor, vision, thermal sense, and tactile sense. Such multi-modal communication is another research focus, and we study acoustic, thermal and chemical information.
Thermal image showing that honey bees have elevated body temperatures after returning from a rich nectar source.
Honeybees use functionally referential communication, the transfer of environmental information into coded signals understood by a conspecific receiver. Such a system may be a sophisticated form of animal communication because of the cognitive complexities presumably involved in transforming sensory information into coded communication signals. However, the question of how referential communication has evolved remains relatively unexplored. Stingless bees are an excellent model for the evolution of animal language because they possess the widest diversity of species and communication strategies, including the ability to acoustically encode the distance and height of food sources. Moreover, some species may use functionally referential communication.
For example foragers of the stingless bee, Melipona panamica, can communicate the three-dimensional location of food sources. To achieve this, foragers use a combination of mechanisms, including potential encoding of distance and height through sound pulses produced inside the nest.
Melipona panamica forager (number 33) recruiting nestmates.
Why has such a complex communication system evolved? Some stingless bees, such as the aggressive Trigona spinipes, can eavesdrop and orient towards the odor mark deposited for good food sources by other species such as Melipona rufiventris.
Aggressive Trigona spinipes forager attacking and killing an Africanized honey bee.
Limiting the conspicuousness of odor marks via strategies such as decreasing odor trail length could be an effective counter strategy to such eavesdropping. However, this would also decrease the amount of guidance information offered to recruits. Providing encoded location information, functionally referential communication, at the nest would replace such lost odor trail information. Interestingly, all bees for which there is some evidence for functionally referential communication, including honeybees, use only point-source odor marking. Whether this is due to eavesdropping and aggressive competition, remains to be determined. However, stingless bees and honeybees still aggressively compete in the environments and regions in which they evolved. Thus, eavesdropping may have contributed to the evolution of functionally referential communication at the nest.
Mapalad, K. S., Leu, D. and Nieh, J. C. (2008). Bumble bees heat up for high quality pollen. Journal of Experimental Biology, 211:2239-2242.
Contrera, F. A. L. and J. C. Nieh. (2007). The effect of ambient temperature on forager sound production and thoracic temperature in the stingless bee, Melipona panamica. Behavioral Ecology and Sociobiology 61:887-897.
Nieh, J. C., León, A., Cameron, S., and Vandame, R. (2006) Hot bumblebees at good food: thoracic temperature of feeding Bombus wilmattae foragers is tuned to sucrose concentration. Journal of Experimental Biology 209: 4185-4192.
Nieh, J. C. and Sanchez, D. (2005) Effect of food quality and location on thoracic temperature in the stingless bee, Melipona panamica. Journal of Experimental Biology 208:3933-3943.
Nieh, J. C., Contrera, F. A. L., Yoon, R. R., Barreto, L. S. and Imperatriz-Fonseca, V. L. (2004) Polarized short odor-trail recruitment communication by a stingless bee, Trigona spinipes. Behavioral Ecology and Sociobiology, 56, 435-448.
Nieh, J. C., Barreto, L. S., Contrera, F. A. L. and Imperatriz-Fonseca, V. L. (2004) Olfactory eavesdropping by a competitively foraging stingless bee, Trigona spinipes. Proceedings of the Royal Society of London B, 271, 1633-1640.
Nieh, J. C., Contrera, F. A. L. and Nogueira-Neto, P. (2003) Pulsed mass-recruitment by a stingless bee, Trigona hyalinata. Proceedings of the Royal Society of London B, 270, 2191-2196.
Dr. Nieh received his BA from Harvard in 1991 and his Ph.D. from Cornell University in 1997. He completed a NSF-NATO postdoctoral fellowship at the University of Würzburg, Germany and was a Harvard Junior Fellow from 1998-2000.
