Monday, Jul. 15, 1996

THE FLOWERING CRISIS

By CHRISTOPHER HALLOWELL

Without honeybees and some 200,000 other species of insects, birds and small mammals, plants would be in a terrible predicament. So would humans. These creatures are the world's pollinators, quietly nuzzling and probing flowers for nectar and in the process, transferring DNA-bearing pollen from stamen to stigma. Without their work we wouldn't have healthy fruit and vegetables or viable seeds. We depend on this free service for 90% of our staple crops.

Many of these pollinators are in trouble, however, threatened by encroachment on open spaces, the felling and fragmentation of forests, industrial pollution and overzealous pesticide use. "The pollination crisis," as entomologists Stephen Buchmann and Gary Paul Nabhan term it in a new book, The Forgotten Pollinators (Island Press/Shearwater Books; $25), is not just of concern to beekeepers and rainforest activists. It is, they write, a way to "inform us about how the world works and what is at stake if we simply ignore the needs of pollinators."

A case in point: of the 5 million acres of tallgrass prairie that rippled to the horizon when settlers first forged west across what is now Iowa, only 200 remain, much of it in bits and pieces along highways. Butterflies are the main pollinators of those grasses and flowers, but the variety of vegetation is rapidly decreasing as the butterflies are forced to forage for nectar in ever smaller prairie fragments. Prairie phlox, for example, one of the most common Great Plains flowers, depends on the butterflies to reproduce. But if the phlox is broken up into small stands, the butterflies won't go to it.

Other examples of this environmental Catch-22 are all too easy to find. In 1970 the lowbush blueberry harvest in New Brunswick, Canada, declined by 75% from the previous year after nearby conifer forests were sprayed with pesticides that wiped out the bees that pollinate the blueberries. In parts of the Southwestern U.S., excessive pesticide spraying of Mexican cotton fields just across the border has reduced populations of two moth species that pollinate certain cactus; as a result, the cactus flowers have withered and dropped.

Most conspicuous of the pollinators in crisis are honeybees, the pollinators par excellence among insects. Since being imported from Europe more than 375 years ago, they have spread rapidly throughout the New World. Honeybees typically pollinate 15% of the U.S.'s crops, but lately the bees have been hard hit. Already debilitated by a nasty mite infection, thousands of colonies were exterminated during last winter's unusually severe cold. During the honeybee heyday after World War II, the U.S. had nearly 6 million hives. Now there are less than half that many, and mites continue to plague the remaining colonies. "We are working desperately to produce resistant bee stocks," says Tom Linderer, who directs a honeybee breeding and genetics lab in Baton Rouge, Louisiana, for the Agriculture Department. "But we have only glimmers of success."

Our dependence on honeybees has clearly exacerbated the pollination crisis, but the bees' demise has also served to focus attention on the potential of "native" (as opposed to imported) pollinators. "We need to remember that tens of thousands of other species have been out there all along, working shifts around the clock," says Pollinators co-author Nabhan, director of science at the Arizona-Sonora Desert Museum.

Farmers have long known that some native insects are effective pollinators; native species are largely responsible for pollinating such cash crops as blueberries, cranberries and squash and partly responsible for almost a score of other crops--among them apples, almonds and cherries. With the honeybee in crisis, entomologists and farmers are actively encouraging native species, belatedly realizing that in some cases they are better pollinators than the honeybees they replace.

The alkali bee, for example, is a favorite of alfalfa farmers. It is far more expert than the honeybee at opening the grass's intricate flower to extract pollen, which tends merely to steal nectar without pollinating. Tomato farmers, meanwhile, are turning to bumblebees, which happily pollinate within the confines of huge greenhouses without trying, as the honeybees do, to escape. The rising star of the native pollinators, though, is the blue orchard bee, a handsome metallic-blue creature that can pollinate an apple orchard with an efficiency that would shame even the hardworking honeybee.

If the honeybee doesn't make a speedy comeback, its plight still serves as a valuable warning. "We can no longer afford to risk the security of our food supply on the services of just one insect," says Pollinators' other author, Buchmann, an entomology professor at the University of Arizona. "We are fortunate to have plenty of new pollination partners to choose from." As portfolio managers know, the value of diversity may not be obvious in the short run, but it is the wisest policy over the long haul.