“We found that the bees still visited those flowers contaminated by metal, indicating that they can’t detect metal from afar,” said Ashman. “However, once bumblebees arrive at flowers and sample the nectar, they are able to discriminate against certain metals.”

In the study, the bees were able to taste, discriminate against, and leave flowers containing nickel. However, this was not the case for the aluminum-treated flowers, as the bees foraged on the contaminated flowers for time periods equal to those of the noncontaminated flowers.

“It’s unclear why the bees didn’t sense the aluminum,” said Meindl. “However, past studies show that the concentrations of aluminum found throughout blooms tend to be higher than concentrations of nickel. This suggests that the bees may be more tolerant or immune to its presence.”

These results also have implications for environmentally friendly efforts to decontaminate soil, in particular a method called phytoremediation—a promising approach that involves growing metal-accumulating plants on polluted soil to remove such contaminates. Ashman says this approach should be considered with caution because the bees observed in the study foraged on metal-rich flowers. She states that further research is needed to identify plants that are ecologically safe and won’t pose threats to local animals that pollinate.

The paper, “The effects of aluminum and nickel in nectar on the foraging behavior of bumblebees” first appeared online March 6 in Environmental Pollution. Funding was provided by the Carnegie Museum of Natural History’s Powdermill Nature Reserve in Rector, Pa., a Botany-In-Action Fellowship from the Phipps Botanical Garden and Conservatory in Pittsburgh, an Ivey McManus Predoctoral Fellowship to Meindl, and a National Science Foundation grant (DEB 1020523) to Ashman. The bees were observed at a nature reserve in Western Pennsylvania during August and September 2012.

 

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