Where have all the pollinators gone?

The flowers of a nightblooming cereus cactus appear only once or twice a year. When the buds burst open into white, six-inch-long, flowers, they're almost instantly visited by sphinx moths. The palm-sized insects hum over to feed on the flowers' nectar -- a sugary liquid several times sweeter than Coke.

On the flowers' "opening night" last summer, scientists Gary Nabhan and Steven Buchmann hiked into Arizona's Sonoran Desert, expecting to witness this close encounter of the floral-and-insect kind. They waited . . . and watched. But when the flowers opened, not a single moth arrived.

The absence of the moth worries the scientists because the cactus needs the moth to reproduce. As the moths dine from plant to plant, they distribute pollen (the dusty, yellowish particles that contain plant reproductive cells) to other cereus cacti in the neighborhood. In fact, Nabhan and Buchmann think this moth is the only pollinator of the rare cactus. Without the pollinator, the cacti may soon die.

The scientists are particularly worried because the absence of the moth is just one example of a problem that's growing worse every year -- disappearing pollinators. "Pesticides and the loss of wild lands are seriously shrinking the number of moths, bees, butterflies, and other creatures that pollinate plants," says Buchmann. And since one out of every three bites of food you eat is brought to you courtesy of a pollinator, the pollination crisis could be something even you will soon notice.

FLIGHT INFORMATION

The pollinator you know best is the honeybee. But moths, wasps, birds, bats, and even small animals that don't fly (like lizards) can be pollinators, too. When a critter sips a flower's nectar, pollen grains "hitch a ride" on the pollinator. For example, when the sphinx moth slips its long tongue into a cereus cactus flower, grains of pollen stick to the moth's tongue. When the moth visits another cereus, some of the first cactus' pollen rubs off on the reproductive flower parts in the new plant (see diagram, p. 14).

That fresh crop of pollen particles fertilizes the flowers. Fertilization causes the flower to form seeds. A few weeks later, a fruit develops around the seeds. Eventually, the seeds will be reborn as a new, healthy plant -- and the cycle continues.

THE PROBLEM

Without pollinators, most plants can't reproduce. And without plants to provide food, pollinators die. Of the 1,035 known species of pollinators, 103 birds, 82 mammals, and 1 reptile are threatened to some degree. And those figures don't include the hundreds of insects whose populations continue to shrink each year.

"We've got a very dangerous situation brewing," says Buchmann. If any of these pollinator or plant species should become extinct, the effects could run right up the food chain: First, the animals that eat the plants or pollinators would starve, or at the very least be forced to eat other things. Then, the animals who eat those animals would suffer. This creates more competition for food resources. Eventually, entire ecosystems -- groups of interdependent species -- could collapse.

Because humans eat fruits and vegetables that need pollination to grow (like potatoes, tomatoes, and onions), the pollinator problem could affect you in the next few years. As shortfalls occur, ordinary fruits and vegetables may become harder to find in your supermarket. if you do find them, they'll be more expensive, because reduced supplies drive up prices.

Farmers are already starting to feel the effects of pollinator shortage. For the first time ever, dwindling bee populations in 1994 forced many California almond farmers to import honeybees from other states to make sure that year's crop would be pollinated. If people don't heed the warning signs now, Nabhan and Buchmann warn, it may be too late.

POLLINATOR DANGERS

One of the biggest threats to pollinators is the heavy use of pesticides that are meant to kill crop-eating pests. When pesticides are sprayed carelessly on areas near crop fields, many pollinators can be obliterated. "Pesticides are one reason U.S. honeybee populations have dropped 25 percent since 1990," Buchmann says.

An even more serious threat to the world's plants and pollinators is land development. That's when areas of "wild" land are turned into farms, shopping centers, and housing developments. Pollinators need wide stretches of open land to nest and hatch their eggs. When that land is broken up into pieces, pollinators have a more difficult time finding the plants they feed on.

Say a sphinx moth catches a whiff of cactus flowers. "If the moths hit a half-mile-wide housing development en route, their sense of smell is thrown off," explains Nabhan. "They start flying around in circles, never reaching their destination."

SAVE THE BIRDS AND BEES

What can be done to protect pollinators? Park planners could fill nature reserves with plants and the pollinators that love them. Nabhan arid Buchmann also suggest that farmers use less toxic pesticides to spray crops. They could also target only pest-filled crops -- not nearby areas where pollinators may be feeding or nesting. Buchmann and Nabhan are also asking farmers to set aside areas of land outside their crop fields to protect pollinators' habitats.

What can you do? No matter where you live you can encourage pollinators to visit! Here are a few ideas:

* Make a wild bee nest (see "Build a Bee Nest!" at left). springtime, wild bees search for safe places to breed. Since wild bees are actually better pollinators than honeybees, you'll be directly helping to increase the pollinator population. And don't worry; these bees only sting when threatened.

* Plant a window box or garden with plants pollinators love, like butterfly bush, mint, or any plant with red tubular flowers. (Or encourage your parents or others who have gardens to plant these flowers.)

* Avoid using pesticides in your garden.

* Buy organic fruits and vegetables, which are grown without pesticides.

To learn more about Nabhan and Buchmann's efforts to save pollinator's -- called the "Forgotten Pollinators" campaign -- check out this Web site:

http: //w w w. desert.net/ museum/fp/

Made for each other

Why can a butterfly pollinate a daisy but not the red flower shown below? Because flowers and pollinators have co-evolved -- changed together over millions of years -- to be perfectly matched for one another.

To attract certain pollinators, plants have developed specific traits -- flashy colors, special petal arrangements, or great smells. For example, the flat spread-out petals of a daisy make an easy landing pad for butterflies, moths, and many other insects. Bright red tube-shape flowers are particularly appealing to hummingbirds.

And just as plants have adapted to attract specific pollinators, some pollinators are best suited to pollinate certain plants. The hummingbird's long, slender beak, for instance, can sip the nectar deep inside tubular flowers. Species without this beak or a similar adaptation couldn't reach the sweet reward.

Because many of these pollinator-plant relationships are so specific to one another, the loss of any one species is all the more dangerous. If a species of pollinator becomes extinct, its "chosen" plant species could also die out.