America is often called a land of plenty, celebrated anthems for its fruited plains and "amber waves of grain." The nation's bounty owes to rich natural resources and the hard work of people, as well as to the efforts of dimunitive creatures that are rarely the subject of ballads: the pollinators that plants depend on for reproduction.
Pollination is the transfer of microscopic pollen grains from the anther, the flower's male organ, to the female organ or stigma. In the case of self-pollination, this transfer occurs within the same flower between flowers on a single plant. Pollen can also transported-either by wind, water, or animal-from the male part of one plant to the female part of another, a process called cross-pollination.
An estimated 100,000 to 300,000 animal species including bees, butterflies, moths, birds, and bats serve as middlemen, or "middlewomen," in this process. More than 80 percent of the world's 250,000 flowering plants depend on animal pollinators, and roughly 15 to 30 percent of the food eaten throughout the world comes from plants pollinated by these creatures. Pollinators help perpetuate not only our croplands, but our gardens, forests, pastures, and meadows, thereby supporting human economies in the narrow sense and natural ecosystems on a large scale, with all the benefits they confer.
Insects don't get a lot of respect in our society, yet honeybees and other insect pollinators make a big contribution to the American GNP. According to the U.S. Department of Agriculture, crops dependent on pollination by honeybees and other animals are worth more than $10 billion a year. By some estimates, that figure rises to $40 billion per year domestically, and $200 billion worldwide, when livestock feed crops are included in the tally.
Ecologists are nowhere close to documenting all the valuable services performed by the 100,000 or more pollinators. While dispensing pollen, bees, bats, birds, and other animals also add to ecosystem productivity by facilitating the spread of seeds and the redistribution of nitrogen-rich wastes. With their contributions largely unrecognized, pollinators hold their place as the unsung heroes of the natural world.
More than 80 percent of the world's 250,000 flowering plants depend on animal pollinators, and roughly 15 to 30 percent of the food eaten throughout the world comes from plants pollinated by these creatures.