University of Illinois entomologists have discovered that feeding high-fructose corn syrup and other honey replacements to honey bees may be linked to colony collapse disorder. The findings were recently published in the Proceedings of the National Academy of Sciences.
As reported on this site last week, a special USDA/USEPA honey bee health report confirmed that multiple factors play a role in the demise of honey bee colonies around the world. Key culprits noted included parasites, disease, genetics, pesticides and poor nutrition. The Illinois report takes aim at poor nutrition.
The Illinois researchers, Wenfu Mao, Mary Schuler and May Berenbaum, suggest the real culprit might be high-fructose corn syrup and other honey replacements, which beekeepers have been feeding bees, instead of their natural staple, honey.
Commercial honey bee enterprises began feeding bees high-fructose corn syrup and other substitutes back in the 70's after research indicated it was safe to do. Since then, new pesticides have been put into use and over time it appears the bees' immunity response to such compounds may have become compromised.
What's going on
The researchers didn't suggest that high-fructose corn syrup is toxic to bees. Instead, their findings indicate that by eating honey substitutes instead of honey, the bees aren't receiving enough nutraceutical compounds to strengthen their immune systems to fight off diseases and toxins meant to kill other insects.
Specifically, they found that when bees are exposed to the enzyme p-coumaric found in pollen walls, their immune systems appear stronger. The enzyme turns on detoxification genes.
P-coumaric makes its way into honey inadvertently via sticking to bee legs as they visit flowers. The team also discovered other compounds found in poplar sap that appear to do much the same thing.
And they found that adding p-coumaric acid to a diet of sucrose increases midgut metabolism of coumaphos, a widely used in-hive acaricide, by about 60%.
Diet makes a difference, even for bees. Taking away the honey to sell it, claim these researchers, compromises bee immune systems and makes them more vulnerable to other stress factors.