Nieh suggests that communicating the location of the food source to nestmates within the confines of the nest may have evolved as a strategy to avoid broadcasting information about the food source to competitors, which may also be able to follow the scent trail. The abbreviated scent trail strategy was observed in T. hyalinata, one species of stingless bee, a diverse group prevalent in South America. This discovery by Nieh and his colleagues Felipe Contrera and Paulo Nogueira-Neto from the University of So Paulo lends support to the notion of chemical eavesdropping, "espionage," driving the evolution of communication.

Besides the length of the stingless bees' scent trail the short trail has a second unique feature. The scent drops are more concentrated at one end of the trail than the other.

"All previously discovered bee scent trails had a roughly equal number of drops per unit distance," says Nieh. "Here the scent markings are highly concentrated around the feeder and they taper off at increasing distance from it, in a trail that is roughly teardrop-shaped."

Remarkably, the bees fly to the point with the highest scent concentration, and will ignore food placed at other locations along this scent trail, even if it is closer to the hive. Nieh hypothesizes that this scent gradient permits the bees to pinpoint a specific food source, enabling them to arrive en masse.

T. hyalinata is very aggressive. These bees will readily attack other bees of different species, or bees of the same species from different colonies. Because they can better compete for food, Nieh says it is advantageous for aggressive bees to arrive at a food source in large groups. Similar behavior occurs in other types of aggressive insects; for example, army ants arrive in "enormous hor
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Contact: Sherry Seethaler
858-534-4656
University of California - San Diego
22-Sep-2003