Rising levels of carbon dioxide in the atmosphere may be impacting bees more than we thought. Scientists have found that rising CO2 is affecting the protein in goldenrod pollen, which is a key late-season food source for North American bees.
In previous studies, scientists found that increases in carbon dioxide can lower the nutritional value of plants such as wheat and rice. However, this is the first study to examine the effects of rising CO2 on pollen.
Native bee species and honeybees rely on flowering plants for energy and nutrition. In fact, pollen is the sole source of protein for bees. If the protein content in pollen goes down, then bees may have less of a chance of survival, especially when considering the other challenges that they face.
In this latest study, the researchers focused on goldenrod, which is a common North American perennial that blooms from late July through October. They examined the protein levels in historical and experimental samples of goldenrod pollen. In the end, they found that pollen protein levels dropped about a third in samples collected from 1842 to 2014, a period during which the amount of carbon dioxide in our atmosphere rose from about 280 parts per million to 398 ppm.
"Bee food is less nutritious than it used to be," said Jeffrey Dukes, co-author of the new study from Purdue University. "Our findings also suggest that the quality of pollen will continue to decline into the future. That's not great news for bees."
It's not just that bee food is less nutritious than it used to be, either. It's likely that the nutritional content of pollen will continue to decline in the future. This means that bees may be in trouble as carbon dioxide levels continue to rise.
"A poor diet sets bees up for failure," Dukes said. "Previous research shows bees have shorter lifespans when fed lower quality pollen."
The findings highlight the importance of taking action now in order to help bees survive. Already, bees are declining due to pesticides and monoculture practices. Adding in the fact that low-quality pollen may also be a factor means that real steps will need to be taken in order to preserve these pollinating insects.
The findings are published in the April 2016 edition of the journal Proceedings of the Royal Society B.
