Web edition: March 1, 2013
Honeybees may be busy, but they may not be efficient: Native pollinators could help farms worldwide produce bigger harvests.
Without the aid of local free-living pollinators, “we are not reaching the potential yield we could,” says Lucas Garibaldi of the National University of Rio Negro and Argentina’s CONICET research network. Communities of wild pollinators are more efficient overall than honeybees, he says. Crop yield increased as more wild visitors came to farms.
Garibaldi and an international team reported February 28 in Science.
The paper argues the global importance of native pollinators, says insect ecologist Frank Drummond of the University of Maine in Orono who was not one of the 50 coauthors. “It’s not just some little teeny field,” he says.
Farmers have long assumed that wild insects “could be replaced with a lot of hives of honeybees without any problem,” Garibaldi says. Biologists knew that wild pollinators matter to wild plants as well as to certain crops such as blueberries, but not to commercial agriculture as a whole.
Garibaldi and his colleagues looked at details such as the rate at which particular insect species visited flowers at 600 sites growing a total of 41 crops on all continents except Antarctica. Farms varied from industrial-scale almond farms and full-sun coffee operations to backyard cucumber patches. Native pollinators enhanced yields regardless of whether farmers provided honeybees as well, Garibaldi says.
Now, ecologist Bradley Cardinale of the University of Michigan in Ann Arbor would like to know what makes the wild insects so efficient. In the analysis, pollinator diversity alone did not influence yield, leaving open the long-standing question of whether the actual variety of organisms might influence agriculture.
As for the pressing matters for farmers, the paper answers whether native pollinators are useful, Drummond says. “The second question is, OK, how are we going to try to really take advantage of them?”
Growers have been taking a new interest in native pollinators because health problems and rental prices have increased for U.S. honeybees, Drummond says. But taking advantage of native pollinators may not be easy. For Maine’s blueberry growers, for instance, wild bees do a fine job at pollinating. Yet wild pollinator numbers fluctuate, so growers often bring in honeybees to keep from getting caught short.
Giant farms would also need giant supplies of wild species. An independent experiment in boosting almond yields has mixed the wild blue orchard bee species with rented honeybees in California fields, says Theresa Pitts-Singer of the Department of Agriculture’s Bee Biology and Systematics Laboratory in Logan, Utah. So far, she and her colleagues have found that the blue orchard bees seem to efficiently pollinate the almonds, but no significant populations live near the fields, and collecting them elsewhere could deplete another ecosystem.
A second study in the Feb. 28 Science feeds worries about the status of wild pollinators. Researchers studied a rare set of detailed records from the late 19th century and found that only 54 of the 109 bee species known then still buzz around a suite of woodland flowers near Carlinville, Ill. Even when both bee and flower species survived the intervening century, 48 former bee-flower partnerships now fail, the researchers found, because climate change has knocked their timing out of sync. And 38 additional bee-flower connections have broken because partner species no longer live in the same neighborhood, Laura Burkle of Montana State University in Bozeman and her colleagues report.
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