Researchers Are Using ‘Bee Doctors’ To Treat Cherry Tree Disease

CREDIT: AP Photo/Al Behrman

A honey bee collects pollen from a flowering tree, Monday, April 12, 2010, in Cincinnati.

The future of fungus-free crops may depend not on fungicides, but on a few fuzzy insects, if a method used by Australian researchers can be successfully replicated.

The researchers are using bees as “flying doctors” to deliver a biological control agent that prevents a debilitating fungus to the blossoms of the cherry trees they pollinate. The agent — which contains spores of another fungus that prevents brown rot, a blight that’s prevalent among cherries and other stone fruit — is sprinkled into dispensers on the front of the bees’ hives. The spores cling to the bees when they leave the hive, and then rub off on the flowers the bees land on to gather nectar and pollen.

“Normally growers spray once or twice during flowering to prevent brown rot in cherries later in the season” Katja Hogendoorn, project leader for the bees-as-fungus-fighters project, said. “Because they are spraying flowers, and bees go to flowers, we can use bees to deliver the control instead.”

The technique works in place of spraying fungicide on the trees to protect them from brown rot, which can cause extensive losses if it infects cherry trees. That makes it a more environmentally sound way of preventing brown rot on cherry trees, which can be pollinated by bumblebees or honeybees.

“The bees deliver control on target, every day,” Hogendoorn, said. “There is no spray drift or run-off into the environment, less use of heavy equipment, water, labor and fuel.”

Bees are already used in the same way in Europe to protect strawberry plants against grey mold, but this is the first time they’re being used on cherry trees in Australia. About half of the strawberries sold in the U.K. each year succumb to grey mold, which can’t be detected until after the strawberries are harvested.

In the past, chemicals have been used to try to curb the mold, but the pesticides are only effective if sprayed onto flowers that are already open. Since flowers on a strawberry plant don’t all open at once, the pesticide has to be applied repeatedly in order to be truly effective. Bees, on the other hand, can carry the mold-preventing fungus to the open flowers they visit over time, making them an efficient and environmentally-friendly way to prevent the mold.

“There is a movement to reduce the use of conventional plant protection products, because they may not be sustainable,” Harriet Roberts, who works at an agricultural consultancy testing how bees can be used in agriculture in the U.K., told the Guardian.

The method hasn’t been used extensively so far — it’s being tested mostly on strawberry and cherry plants — but it could be useful for raspberries, almonds, grapes, and other stone fruits.

The news of their ability to act as buzzing fungicides only further cements bees’ — both of the commercial honey and bumble variety and of the wild sorts — value to mankind (though as Richard Conniff argued in the New York Times last week, that usefulness — or the human-perceived usefulness or uselessness in any other wild creature — remains separate from its intrinsic value). Bees are critical pollinators of several key crops in the United States. One-third of all food and beverages consumed in the U.S. are dependent on some sort of pollination, according to the USDA, and major crops such as almonds and squash depend heavily on bees for pollination. The Department of Defense is testing whether or not honeybees can be used to sniff out landmines, and similarly, their ability to sniff out bombs is also being tested. Bee hives have even been used in parts of Africa to keep elephants from getting into crops: when farmers placed beehives around their fields, the elephants steered clear.

But as most readers probably know by now, commercial honeybee populations have been hit hard in recent years by colony collapse disorder, and some species of bumblebees have also shown population declines. To try to stem these losses, President Obama signed an executive order on pollinator health in June, which creates a task force that will come up with ways for the U.S. to better address problems facing bees, butterflies and other pollinators.