CES - Pollination Tool Kit: Who Are the Pollinators?

Who are the Pollinators?

Managed and Feral Honeybees
Honeybees (Apis mellifera) are often the first things that come to mind when someone mentions pollinators. This common association is a likely consequence of the honeybee's prevalence in agriculture and their capacity for adapting to many environments. Since 1992, over one million honeybee colonies have been rented from commercial beekeepers yearly for pollination of agricultural crops in the United States (25). In addition, honeybees from feral (wild) colonies can be found pollinating flowers and scouring for food in most backyards and gardens throughout the country. Interestingly though, honeybees are not native to the United States; they were brought here from Europe in the seventeenth century to provide honey and wax — two products the 3,500 species of native bees do not produce in commercially useful amounts (10).

There has been recent concern among the agricultural industry as researchers have accumulated evidence showing that honeybee colonies are seriously threatened in the United States. Managed and wild colonies have declined by twenty-five percent during the 1990s and by nearly fifty percent since 1945 (1). Many factors are believed to be responsible for the declines, including: two exotic species of parasitic mites introduced to the United States in the 1980s; pesticide use; extreme weather conditions; and the continuing invasion of Africanized honeybees (1,28). (For more information on Africanized honeybees, see case study, "Invasion of Africanized honeybee to North America".) Many experts suggest that these declines illustrate the danger of our heavy reliance on a single species for most of our pollination needs.

Wild Pollinators
Wild pollinators comprise a significant portion of the total diversity of species on this planet. In fact, over 100,000 invertebrate species — such as butterflies, beetles, moths, flies, and many species of bees — serve globally as pollinators. There are also at least 1,035 species of vertebrates, including birds, mammals, and reptiles, known to provide pollination services worldwide (16). A few colorful examples include (4,18,29):

•	The monarch butterfly and the bumblebee are both common pollinator species enjoyed in gardens throughout the United States.
•	A hawkmoth from Madagascar, with its 12-inch proboscis, can reach into the deep floral tubes of some orchids, where others cannot, to obtain nectar.
•	Male mosquitoes are effective pollinators of many plants worldwide, including rare orchids in the peat bogs of America's upper Midwest.
•	The bee hummingbird is slightly larger than a bumblebee and can remove nectar from a flower in flight by beating its wings up to 100 times a second.
•	The white-winged dove serves as a pollinator to the saguaro cacti, the massive cacti synonymous with images of the southwest United States.
•	The flying fox, a giant bat from Southeast Asia with wingspans up to five feet, is one of over 300 bat species that serve as pollinators worldwide.

Wild pollinators other than honeybees are also often overlooked as important and viable pollination resources. Yet, native bees, butterflies, moths, and flies are at least equally and in some cases even more adept than honeybees at pollinating the 100–150 major US crops requiring pollinators (1). On a global scale, at least twenty genera of animals other than honeybees provide pollination services to many of the world's 100 most important crops. Collectively, these species pollinate at least as many crop species as do managed honeybee colonies (16). For example:

•	There are nearly 4,000 species of bees native to the continental United States. These native bees pollinate many crops that are ineffectively pollinated by honeybees including blueberries, cranberries, eggplants, kiwi fruits, and tomatoes (4,14).
•	Bats pollinate most of the rainforest canopy trees on oceanic islands, as well as many economically important plants such as wild bananas, agave, durians, and several species of eucalyptus and palms (1).
•	Most of the world's 750 fig species rely on wasps for pollination. Figs are a critical resource for both people and animals living in many tropical forest communities. In some areas, figs may constitute as much as seventy percent of the diet of vertebrate species (11).