Bees and Social Insects: Highly Complex Chemical Communications

And we thought we were so great with Alexander Graham Bell, Nikola Tesla and iPhones. Turns out that bees, ants and wasps have a system of signaling by chemicals, and it is far more complex than previously thought.

Researchers from Penn State University and Tel Aviv University recently learned information that refutes the previously-held idea that one group of chemicals has a hold over reproduction across several species, according to a release.

"While the hypothesis that many social insect lineages all use the same chemical signals -- known as pheromones -- was fascinating, we were skeptical that such complex behaviors could be regulated by a simple, common mechanism across such very different species," said Etya Amsalem, a postdoc fellow in entomology at Penn State, in the release. "It seems more likely that pheromones evolved uniquely in different species, as these species experienced different environments and different social pressures."

Their findings were recently published in the journal Proceedings of the Royal Society B.

To provide a bit of background on bee knowledge, most females (the workers) in a colony help rear the queen's eggs rather than laying their own. Ansalem conducted their study to find out whether c25--which is generally thought to be the queen's pheromone, believed to cause worker inhabitation and failure to reproduce-and two near-relation chemicals, c23 and c27, inhibited worker reproduction in the North American bumblebee called Bombus impatiens.
The team examined workers' ovaries to learn the size of developing eggs-evaluating whether they were ready to lay-and looked at how many eggs workers laid and the amount of time it took for them to do that, according to a release.

"We found no effect of exposure to any of the chemicals on the size of the developing eggs, the number of eggs laid or how long it took for the bees to lay eggs," Grozinger said in the release. "Interestingly, we did find that all three chemicals increased the rates of ovary regression. However, ovary regression was positively correlated with time to egg laying. The earlier the workers laid eggs, the more bees showed ovary regression by the end of the experiment. We conclude that ovary regression is likely more a measure of active egg production than evidence for inhibition of egg production." According to Grozinger, overall the results demonstrate that these chemicals do not inhibit ovarian activation in workers.

The researchers said that their team's study contributes to a larger debate concerning how pheromonal signals might evolve and how social behavior is maintained. It also contributes to the debate about which measures should be used to investigate queen bee effects on worker reproduction, the release confirmed. 

"We have learned that pheromone biology is not as simple as was once believed," Christina Grozinger, Penn State professor and director of that university's Center for Pollinator Research, said in the release. "It is not accurate to conclude that worker reproduction is regulated by a simple, common mechanism across different species. Instead, these pheromones likely evolved uniquely in different species. Beyond these chemicals, there may be many more complex and species-specific signals being used by social insects that are yet to be discovered."

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