Proof of Pollination

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As honeybees pick up pollen and nectar, they pollinate about one-third of the plants in the human diet. “Growers rent honeybees to pollinate their crops, and we are taking a close look to see what kinds of pollen the bees are actually collecting,” says Sujaya Rao, entomologist in Crop and Soil Science.

Using a scanning electron microscope, Rao, graduate student Sarah Maxfield-Taylor and emeritus entomologist Bill Stephen have studied pollen collected by honeybees and bumblebees in and near blueberry and red-clover fields. They have focused on pollen caught in hair on body parts such as the leg and head, rather than on the “pollen load,” a ball made of nectar and pollen that bees take back to the hive.

Even the tongue accumulates pollen grains, which rub off the plant as the insects work their way into flowers and use their tongues to collect nectar. Bumblebees tend to have longer tongues, says Stephen, which are well adapted to specific types of flowers.

Their images show how pollen picked up by the bees can vary depending on which plants are in bloom. These show pollen on a bee’s legs, head and tongue.