People in the Partnership
by Susan Lumpkin
People are third-party beneficiaries in many plant-animal pollination partnerships, relying on them for a great deal of their food. In fact, one-third of human food production depends directly or indirectly on pollinating insects, as does the production of many other non-food crops such as cotton, flax, and linseed.
In their 1986 book, The First Resource, Christine Prescott-Allen and Robert Prescott-Allen list some 60 crops grown or imported by the United States that depend on animals for pollination, either to produce fruit or for propagation. The list includes such diverse food crops as onions, cranberries, radishes, cabbage, avocados, almonds, apples, and squash.
Growers rely largely on imported honeybees (Apis mellifera) brought in by beekeepers to pollinate their crops, but native wild insects are important supplemental pollinators of nearly 40 crops, and primary pollinators of seven more: cashew, mango, highbush blueberry, cranberry, squash, cacao, and cardamom. In some cases, the native wild pollinators are more efficient at the job than the imported honeybees.
Two groups of wild bees known as squash bees, for example, seem to be specifically adapted to pollinate squash. Both the bees and the squash (with gourds, watermelon, and other melons, known as curcurbits) are native to America, and as the range of squash expanded due to cultivation, so did the range of bees. Squash is unusual in that its pollen is available very early in the morning, even before daylight. The squash bees, in turn, are early risers, with the ability to fly at low temperatures in low light to collect pollen. In contrast, honeybees wait for the warming sun before they fly later in the day. The squash bees also sometimes spend the night in squash blossoms and emerge in the morning laden with pollen. Finally, curcurbits produce very large pollen grains that the bees are perfectly designed to collect and carry from flower to flower.
Unlike many biological relationships, the value of the partnership between crops and animal pollinators can be measured in economic terms. Crops grown or imported by the U.S. that are dependent on native wild pollinators are worth more than $1.3 billion a year. And according to the U.S. Department of Agriculture, crops grown in the U.S. that depend on animal pollination of any kind, including honeybees, are worth more than $10 billion a year.
Return to Pollination.
(ZooGoer 24(4) 1995. Copyright 1995 Friends of the National Zoo. All rights reserved.)
