Honeybees taste soy in new study

Soy’s reputation as a poor nectar source for honey bees may be unfair, as studies of honey bee pollen patterns and sway dances show a clear attraction to nearby soybean fields. Shown here is a honey bee (Apis mellifera) screening soybean flower for nectar. (Photo by Sreelakshmi Suresh)

By Ed Ricciuti

Ed Ricciuti

Among beekeepers, soybeans are considered a poor source of nectar for honey bees, but Ohio State University scientists think this staple crop doesn’t deserve the bad publicity.

This is good news for honey bees (Apis mellifera) and for the people who grow them, because soybean production has increased 13-fold worldwide since the 1960s, with nearly 90 million acres under cultivation in the United States alone.

“Future research efforts aimed at enhancing the interaction between soybean and honey bees may be an unexplored way to increase soybean production while supporting honey bees and other pollinators in the environment,” the researchers wrote in a study published in September. Journal of Economic Entomology. “Beekeepers can unknowingly harvest significant amounts of soybean honey.”

At first glance, soybean plants don’t seem attractive to honeybees, among whom they rarely forage, the researchers said. However, bees can be noisy without being seen among the small, pink soybean flowers hidden under a thick canopy of leaves. Moreover, the amount of nectar produced by different soybean varieties varies, so some are more productive than others.

To analyze the role that soybean flowers play in honey production, Ohio State University researchers analyzed pollen from honey samples taken from apiaries near Ohio soybean fields at the microscopic and molecular level and combined these results with observations of honey bee swaying dances. Shown here are red-stained soybean pollen grains found in honey samples. (Photos courtesy of Chia-Hua Lin, Ph.D.)

A researcher at Rothenbuhler Honey Bee Company in Ohio, Ph.D. “In this study, we found that honeybees are actively foraging on soybeans in Ohio and that soybean flowers play an important role in honey production,” says Chia-Hua Lin. Laboratory and lead author of the study.

honey-bee (Apis mellifera) approaches the soybean flower. (Photo by John Ballas)

The Ohio State team came to its conclusion after taking a two-pronged approach to determine the value of soybean farming to honey bees. The team analyzed pollen at the microscopic and molecular level in honey samples taken from apiaries near Ohio soybean fields. The researchers combined these results with observations of honey bee swaying dances in two experimental colonies near soybean plants at the Molly Caren Agricultural Center near London, Ohio. The swaying behavior is an instinctual choreographed dance by which honey bees communicate the location of nectar sources to their hive mates. The length of the line the bee swings indicates the distance from the hive. It indicates the angular direction from the line perpendicular to the earth away from the position of the sun during flight.

The results showed that the proportion of soybean pollen in honey increased during the July-August flowering period. Overall, the researchers say, “Soybean pollen…was detected in 17 (55 percent) of 31 samples analyzed.”

The strong preference of honeybees for soybeans was noteworthy. According to the study, honeybees explored “soybean fields more than other foraging sites within 0.5 to 1.5 kilometers from the hive.” Outside of these parameters, bees fed between soybeans or other nectar sources, with the ratio of soybean nectar depending on its availability, was a range. At no distance did bees prefer nonsoybean habitats over soybean plots.

Waggle dancers were videotaped and analyzed with special software. In general, bees preferred soybean fields for foraging over other habitat types. The closer the bees were to the hive, the more soybeans they fed.

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