A new study from the University of Pittsburgh suggests a different reason bumblebees may be dying off, and it’s not due to a class of pesticides.

According to the new study, the research is pointing to metal pollution from aluminum and nickel as the main culprit behind the deaths of bees.

Published in the journal Environmental Pollution, the study found that bumblebees are at risk of ingesting toxic amounts of metals like aluminum and nickel found in flowers growing in soil that has been contaminated by exhaust from vehicles, industrial machinery and farming equipment.

The study showed that bumblebees have the ability to taste—and later ignore—certain metals such as nickel, but can do so only after they visit a contaminated flower. As a result, the bees are exposed to the toxins before they realize the metals are there.

“Although many metals are required by living organisms in small amounts, they can be toxic to both plants and animals when found in moderate to high concentrations,” said Tia-Lynn Ashman, principal investigator of the study and professor and associate chair in Pitt’s Department of Biological Sciences in the Kenneth P. Dietrich School of Arts and Sciences. “Beyond leading to mortality, these metals can interfere with insect taste perception, agility and working memory—all necessary attributes for busy bumblebee workers.”

The results of the study imply a need for environmentally friendly ways to decontaminate soil. One approach called phytoremediation is a promising approach that involves growing metal-accumulating plants on polluted soil to remove such contaminants.

To read more about the study, click here