Pollination is the transfer of pollen, containing the male gamete of a plant, from the anthers where it is produced to the receptive stigma, the female part of the same or another plant of the same species. This process results in fertilization, and sexual reproduction of the plant to produce seeds. Most ancient plants were pollinated by wind. Grasses, conifers, and many deciduous trees are still wind-pollinated. Most flowering plants, however, utilize living organisms to aid in this transfer. Birds and bats can pollinate a limited number of plants, but the vast majority of plants are pollinated by insects. Some wasps, flies, beetles, ants, butterflies and moths pollinate various flowers, but bees are responsible for the vast majority of pollination. And honey bees perform more than 80 percent of all pollination of cultivated crops.
More than 100 important crops are pollinated by honey bees. This includes many of the fruits and vegetables that we eat, but also a number of important crops such as nuts, herbs, spices oilseed crops, forage for dairy and beef cattle, as well as medicinal and numerous ornamental plants. Even plants that are not grown for their fruits require pollination in order to propagate them by seed. Honey bees add an estimated $15 billion to the U.S. economy each year in increased crop yields.
Many species of pollinators have been in decline recently. European honey bees were brought to North America by colonists in the 1600s. As many of these bees escaped into the wild, the feral populations began to displace some of the estimated 4000 native bee species. These feral honey bees provided pollination for the growing agricultural industry across the county through the 20th century. In the 1990s two species of parasitic mites were accidentally introduced from Asia. The tracheal mite and varroa mite caused severe declines in honey bee populations within a few years. These parasitic mites were controlled on managed bees largely with chemical pesticides, substantially increasing the costs of large beekeeping operations. During the same time, populations of feral honey bees dramatically declined. Fewer natural pollinators, combined with increased agricultural production have resulted in an increased need for contracted pollination services. Honey bee hives are placed on trucks each spring and moved from their winter homes to areas of agricultural production in order to provide adequate numbers of pollinators when crops are in bloom. This movement of honey bee hives is thought to be associated with the spread of honey bee diseases and other hive pests.
During the winter of 2006-2007, a high number of bee colonies died out, but the cause of death remained a mystery. The next winter, colonies died out at even higher rates. The phenomenon was termed Colony Collapse Disorder, or CCD, and has been reported in Europe as well as the U.S. This mysterious disappearance of honey bees raised alarms that we may be on the verge of a pollinator crisis, resulting in insufficient numbers of pollinators to supply the demands of our agricultural industry. This pollinator shortage is not likely to result in a large-scale food shortage in the US. However, there may be an increase in the cost of some produce because of the increase in production costs associated with the demand of pollinators. Many of our fruits and vegetables are imported from Asia and Latin America, where CCD has not been largely reported. Most staple food crops, such as wheat, rice and corn, are wind-pollinated. Other crops, such as soybeans, are self-fertile, and are not dependent upon pollinators. And some crops, such as peaches and cotton, can self-pollinate, but when pollinated by bees tend to produce larger yields.
In light of declining honey bee populations worldwide, representatives of Arkansas’ agricultural producers and beekeepers have develop a set of standard practices to encourage cooperation and communication between growers, pesticide applicators, and beekeepers.
The goals of the Arkansas Pollinator Stewardship Program are to minimize economic losses for both farmers and beekeepers by adequately managing row crop pests while minimizing impact of pesticides on honey bee colonies.
|Fruits and Vegetables|
|Herbs & Spices|
Many species of pollinators are in decline around the world due to destruction of natural habitat. This is especially true in industrialized countries such as the U.S. Bees and other pollinators are a vital part of the natural system. Besides humans, many other species rely on pollinators. Plants need pollination in order to reproduce, and many species of wildlife depend on pollination in order to find their food as well. Gardeners and homeowners can plant a variety of trees, shrubs, and flowers to attract pollinators. By choosing a variety of flowers that provide blooms continuously throughout the growing season, you can ensure that pollinators will return regularly. Find out what to plant in your region by visiting the Pollinator Partnership.
Becoming a backyard beekeeper is a great way to increase the pollinator population in your neighborhood. If you don't want to keep honey bees, encouraging native pollinator species can be very simple. Many species of solitary bees are native to Arkansas. These bees will rarely, if ever, sting. They do not require sophisticated hives or other equipment to maintain. By providing them with simple habitats from scrap wood, you can increase the productivity of your garden. Learn more about encouraging solitary bees.
Solitary bees make great pollinators. Unlike honey bees, they do not live in large colonies, don't produce honey and they do not sting. They are important pollinators of wildflowers across North America. Because they tend to forage in the area near their nests (usually within 500 yards), they can serve as efficient pollinators of small gardens and orchards. Many solitary bees nest in the ground, but bees in the family Megachilidae seek cavities in dead wood in which to build their solitary nests. These nests are provisioned with pollen and nectar, eggs are deposited, and then they are sealed off and abandoned. After overwintering as pupae, the adult adult bees will emerge from the holes in early spring and begin to forage. Male bees will die shortly after mating. Female bees will soon seek a cavity in which to to prepare their own nest. They will often remain in the vicinity of the nest from which they emerged. By providing numerous nesting blocks near garden spots or orchards, solitary bees can be encouraged to remain and reproduce year after year.
Bees in the diverse family Megachilidae include the mason bees and leafcutter bees. These bees lack a pollen basket on their hind legs, as honey bees have. Instead, they carry pollen on the underside of their abdomen. At least 40 species of bees in this family can be found in Arkansas. All will seek out cavities in which to dwell, and can be encouraged as pollinators by providing them with suitable habitats. Leafcutter bees use their sharp mandibles to cut circles from plant leaves with which to line their nesting holes. They are sometimes considered a pest by gardeners because of aesthetic damage to ornamental plants, but they rarely remove enough leaf material to damage plant health. Mason bees get their name from the way they seal their nesting holes with mud after eggs have been laid in the provisioned cells. Many of these bees are excellent early season pollinators of fruit trees and garden vegetables. If you want to encourage mason bees for pollination, be sure there is a source of mud nearby, such as a stream or pond, or you may need to provide them with a source through irrigation.
Megachilid bees do not bore their own nesting holes, but are opportunistic house-hunters. Suitable nesting blocks can be easily built by drilling holes in practically any piece of untreated wood. Different species prefer hole diameters ranging from one-quarter of an inch to three-eighths of an inch, and spaced at least three-quarters of an inch apart. Blue orchard bees are prefer hole diameters of five-sixteenths of an inch. You can experiment with different sized holes, in increments of one-sixteenth of an inch, and see which ones appear to attract the most bees in your area. Holes should be three to five inches deep, and should not be drilled all the way through the wood. Bees will lay male eggs toward the front of the hole, and female eggs behind them. Deeper holes will accommodate more female bees, and therefore increase the number of pollinators for next season.
Sections of hollow bamboo or cane can also be bundled together to provide solitary bee nests. Some people use paper tubes or straws to line the nesting holes, so that they can be removed and the blocks can be cleaned. Occasionally solitary wasps will also take up residence in these holes, but are rarely a problem, and may also contribute to pest control and pollination.
These nesting blocks can be placed around an area to attract bees, and moved to a new area (such as an orchard or garden) before the spring emergence to encourage pollination. Nesting blocks should face the morning sun, and be sheltered somewhat from rain, either by adding an overhanging "roof" to keep rain from soaking the wood, or placing the blocks under the eaves of a barn or shed. Blocks containing dormant pupae can be brought into a shed or barn to protect them extreme cold during the winter, and placed outside again in early spring for pollination.
Native Megachilid bees of Arkansas
|Anthidium maculifrons||Coelioxys texana||Lithurgus gibbosus||Megachile petulans|
|Anthidiellum notatum||Dianthidium subrufulum||Megachile albitarsis||Megachile perihirta|
|Ashmeadiella bucconis||Heriades carnita||Megachile brevis||Megachile pollicaris|
|Coelioxys asteris||Heriades variolosa||Megachile campanulae||Megachile rugifrons|
|Coelioxys edita||Heterathidium ridingsi||Megachile concinna||Megachile texana|
|Coelioxys germana||Heterostelis australis||Megachile exilis||Osmia georgica|
|Coelioxys hunteri||Hoplitis cylindrica||Megachile georgica||Osmia lignaria|
|Coelioxys modesta||Hoplitis pilosifrons||Megachile inimica||Osmia subfasciata|
|Coelioxys octodentata||Hoplitis producta||Megachile mendica||Stelis costalis|
|Coelioxys sayi||Hoplitis truncata||Megachile parallela||Stelis lateralis|
Additional information on encouraging solitary bees
- USDA Guide to Preparing a Solitary Bee Nesting Block
- NCSU Guide to Managing Orchard Mason Bees
- Attracting Solitary Bees
- The bee family Megachilidae
Video clips about solitary bees
- How to Make a Mason Bee Block
- Mason Bees Coming to Life
- Solitary Bees Provisioning their Nesting Holes
- How to Attract Leafcutter and Mason Bees
- Bee Houses: Nest Holes for Solitary Bees