How to tell when a bee has become a picky eater - Haaretz

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Sat., February 02, 2008 Shvat 26, 5768

Israel Time: 01:29 (EST+7)

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How to tell when a bee has become a picky eater

By Ofri Ilani

When Austrian zoologist Karl von Frisch claimed, back in the 1920s, that he had "decoded the language of the bees," many researchers thought he was delusional. Frisch studied the bees "strange dancing" in their hives, and noted that the dancing was a kind of communication, expressing the distance to the nearest source of nectar and its quality.

Only in recent years has Frisch finally been proven correct. Bees actually do use their "dance" to relay information to the hive regarding both the location of the nectar and the quality of this food source.

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The bee moves in a figure-eight pattern; the direction of the diagonal of the eight approximates the direction of the nectar source relative to the sun. The length of the diagonal represents the distance and the number of revolutions per minute represents the nectar's relative quality.

Israeli researchers have now proved that bees express additional information with their dance, such as various substances that affect the flavor of their food.

Ohad Afik, a pollenization expert in the Agriculture Department at Jerusalem's Hebrew University, researched the bee dance for a practical reason: increasing the productivity of avocado orchards. Like other orchard crops, the avocado tree needs bees to visit its flowers and pollenate them, so that the fruit will grow.

Avocado growers all over the world know, however, that bees do not like visiting avocado flowers. Given a choice, bees prefer to collect nectar from citrus blossoms and neglect the avocado. This tendency is a serious problem that often reduces avocado productivity.

Afik wanted to find out why the bees steer clear of the avocado blossoms. "It's a known fact the world over that bees don't come to avocado trees, but no one knows exactly what they don't like," says Afik.

In his previous research, Afik discovered that avocado flowers have a relatively high concentration of potassium, and this finding aroused his suspicions.

"Nectar is composed mainly of water and sugar," explains Afik, "but also contains many other components that are responsible for its odor, color and flavor. Until recently, however, no one thought these other components had any significance for the bees."

Afik's research, which will soon be published in the science journal Animal Behavior, documents the bees' dance after eating avocado nectar and compares it to their dance after eating citrus nectar. Afik, who conducted his research with Drs. Arnon Dag and Sharoni Shafir, put avocado nectar and citrus nectar beside a beehive in a closed room. Afik marked a number of bees with a colored dot, so that he could follow their movements, and videotaped them.

"When we analyzed the dance, we found two differences," says Afik. "After the bees ate the citrus nectar they danced faster, with more turns. One could say that the bees were more excited and were telling their friends that this was a high-quality source." Now that the reason for the avocado blossom's lack of popularity has been identified, the question remains how to make the bees like the nectar.

"One possibility is to reduce the potassium concentration by using less potassium in the fertilizer," offers Afik.

Another option is to develop bees that are less sensitive to potassium. In any event, Afik's research has proved that bees are much more sensitive to flavors than previously surmised.

"We also observed that small quantities of substances are significant to the bees, just as small quantities of salt and pepper in our food affect its flavor."

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