High-fructose corn syrup is not just an ingredient in many human foods. Beekeepers also feed it to their pollinators to encourage colony growth or when nectar is scarce. But dehydration of fructose can lead to formation of trace amounts of hydroxymethylfurfural (HMF), a key biomass-derived chemical that happens to be toxic to honeybees. A group of researchers has now evaluated HMF formation in stored corn syrup and its impact on bee mortality (J. Agric. Food Chem., DOI: 10.1021/jf9014526). Led by Blaise W. LeBlanc, formerly of USDA’s Carl Hayden Bee Research Center, in Tucson, Ariz., and Gillian Eggleston of USDA’s Southern Regional Research Center, in New Orleans, the team found that HMF concentrations increased with time in stored corn syrup, depending on temperature, pH, and possibly the presence of manganese, which is known to catalyze HMF formation in honey. They also found that bee mortality increased significantly when the insects were fed corn syrup containing 250 ppm HMF, compared with 57–200 ppm. The results should be useful to beekeepers evaluating how to safely store corn syrup, the researchers say.