Hymenopterophily: pollination by bees, wasps, or other members of the Hymenoptera Order.
Hymenopterophilous: plants that are pollinated by bees, wasps, or other members of the Hymenoptera Order.
The Alfalfa Farmer's Friend
A female alkali bee (Nomia melanderi). Image by Ken Gray, courtesy of Oregon State University, www.ipmnet.org/kgphoto/.
Alkali bee Nomia melanderi
Description:The alkali bee, Nomia melanderi, is a member of the large and diverse Halictidae family of bees, which includes several genera and several hundred species worldwide. Some halictid species are commonly known as "sweat bees" because they are attracted to the salts in perspiration. Nearly the size of the honey bee, the alkali bee is black with iridescent green, yellow, or blue stripes on the abdomen of both sexes. Males are distinguishable from females by their larger antennae. All halictid bees are pollen feeders and may be important pollinators of both wild and cultivated plants. The alkali bee has become commercially important because it is an efficient pollinator of alfalfa. Halictid bees are generally not aggressive and only sting when swatted or startled.
Life History:The alkali bee is a solitary nester, in contrast to the highly social honey bee and bumble bee species, as well as some other halictid bees. However, alkali bees are gregarious in that individual females nest near one another, with as many as 50 - 100 nests per square foot. The nest is constructed by the female as a vertical tunnel 3 - 10 inches deep, with lateral tunnels terminating in cells. Males loiter near the nest sites, mating with multiple females as they construct the entrance tunnels. The female lines each of about 15 - 20 cells with soil and a waterproof oral secretion and provisions each cell with a 1.5- to 2-mm pollen ball composed of pollen and nectar. The female lays an egg on the pollen and seals the cell with soil. She completes approximately one cell per day. The eggs hatch within three to four days and the larvae consume the pollen balls within a week. Larvae overwinter in their cells, then pupate and emerge as adults in June or July, with males appearing a few days before females.
Habitat:For nesting habitat, the alkali bee requires moist alkaline soils with a salty (sodium or calcium) crust. Soils typically have a silt loam or fine sandy loam texture. Foraging female alkali bees cover a large area, straying up to five miles from the nest site, and visit a variety of flowers, including clovers, mint, onions, Russian thistle, salt cedar, and sweet clovers. However, alfalfa pollen and nectar within two miles of the nest site constitutes the primary food source for most females. Males visit flowers for nectar only. Female alkali bees tolerate a tripping mechanism unique to alfalfa flowers: the flower is held under tension; to gather pollen, the bee must trigger the release of the flower, and the bee's body is hit in the process. This tripping mechanism seems to discourage the honey bee from pollinating alfalfa, but does not deter the alkali bee.
Distribution:The alkali bee is native to the arid regions of the United States, west of the Rocky Mountains. They are managed to some extent in Nevada, Idaho, California, eastern Oregon, and Washington by alfalfa farmers who provide artificial nest sites. This species has also been imported to New Zealand, where it is managed for alfalfa production.
Status:Halictid bees include some of the most common bee species in North America and on some other continents. The alkali bee, in particular, is among the more common native bees in the western United States. In some areas of the western U.S., managed alkali bee populations began to decline in the 1970s - possibly due to insecticide use on alfalfa or neighboring crops - causing some alfalfa farmers to turn to the non-native alfalfa leafcutter bee for pollination services.
Pollinating Bees and Wasps: Getting Down to Buzziness
Sweat bees (Agapostemon virescens), attracted to salts in perspiration, are also important pollinators. Photo Susan Ellis.
Bees are the first creatures that come to mind when people think about pollinators and pollination.
The honey bee (Apis mellifera) is an almost global species. Honey bees can be found pollinating plants throughout northern Europe and Africa (honey bees are native on both continents) and they are also common in the Americas where they were introduced by humans during the early colonization of the continents. Honey bees are best known for their role in the production of honey.
In North America, many native bee species, as well as some wasps, are also important pollinators. The bumble bee (Bombus spp.) is among the most important pollinator of temperate zone plants. Other native bee pollinators include mason bees (Osmia spp.), mud bees (Anthophora spp.), squash bees (Peponapis spp. and Xenoglossa spp.), long-horned bees (Melissodes spp.), sweat bees (Family: Halictidae), alkali bees (Nomia melanderi), and sunflower bees (Diadasia spp. and Svastra spp.).
Habitat loss and fragmentation threaten many of these beneficial organisms. A decline in nectar-producing flowers is one problem, but a loss of nesting habitat may have more serious consequences for some species.
Ants and many bees and wasps are eusocial - meaning they are socially highly organized. Eusocial insects are reproductively specialized, with a reproductive division of labor often involving sterile members caring for the reproductive members. Other defining features of eusociality are overlapping of generations and cooperative care of the young. All ants are eusocial with morphologically different workers and queens. Some bee and wasp species, including honey bees ( Apis mellifera ), carpenter bees ( Xylocopa spp.), bumble bees ( Bombus spp.), paper wasps ( Polistes spp.), and yellowjackets ( Vespula spp.) also exhibit eusociality. Interestingly, humans are also defined as eusocial. (Reference: Social Behavior of Polistine Wasps, Joan E. Strassman, November 8, 2006).
All By Myself: Most Bees Live a Solitary Life
Often when we think of bees, we envision a hive with a single queen who lays eggs and worker bees that look after the eggs, as with honey bees and bumble bees. In fact, 85% of bees are solitary - meaning a single female mates with a male and then constructs, provisions, and lays an egg in each cell in a nest by herself. Examples of solitary bees are the hornfaced bee ( Osmia cornifrons ) and the orchard mason bee ( Osmia lignaria ). Solitary bees do not produce honey or wax, are relatively docile and not apt to sting, and are resistant to parasites and diseases of the honey bee. These types of bees live in nests dug underground or placed in hollows in reeds, bamboo, logs, or other materials. Nesting females may make their nests close together forming aggregations with thousands of nests and bees. Common traits of solitary bees that form aggregations are: they are naturally active at the time a crop blooms, favor this crop's flowers, and can reproduce on a diet of nectar and pollen from the crop.
Native bumble bees, such as Bombus impatiens, may be threatened by the introduction of non-native bumble bees. Photo David Cappaert.
Bumble bees are important pollinators of temperate zone plants for a number of reasons. First, the bumble bee's dense hairs capture pollen quite well, allowing for efficient transfer among flowers. Second, bumble bees can pollinate some wild and cultivated plants, including commercially grown tomato plants, through sonication (or "buzz pollination"), making pollination more efficient. And third, the bumble bee's ability to tolerate a wide range of temperatures and climate types means that it is available to pollinate when and where other pollinators are not.
The two bumble bee species currently used most extensively for agricultural crop production are Bombus impatiens, a native of North America, and B. terrestris, native to Europe. Though relied upon for pollination of many crops, both species are raised commercially for greenhouse tomato pollination.
Some countries outside the native range of B. terrestris have imported this species for commercial crop pollination. In some of these countries, B. terrestris has become naturalized and has expanded its range. Though B. terrestris has not yet been imported to the United States, Mexico allowed its importation in the 1990s to Jalisco for greenhouse tomato pollination.
Researchers and conservationists have raised concerns about the potential impact of B. terrestris on native pollinators. The non-native bumble bee may introduce new diseases, out-compete native species for resources, or disrupt adaptations of native bees (and co-evolvedplant-pollinator associations) by hybridizing with native bumble bees.
In fact, shortly after Mexico allowed for the importation of B. terrestris, the microsporidian Nosema bombi, an internal parasite that infects bumble bees, was found in shipments of B. terrestris. This prompted an end to Mexico's importation of this species in the 1990s. However, for economic reasons, some agricultural producers and bee suppliers are urging governments in Mexico, the United States, and Canada to allow for importation of B. terrestris.
In a recently released white paper, the North American Pollinator Protection Campaign (NAPPC) calls for an immediate evaluation of B. terrestris effects on native pollinators and ecosystems in Mexico and of its potential threat to native pollinators of neighboring countries. The white paper includes recommendations for policy makers in Mexico, the United States, and Canada to prevent negative consequences and to identify alternatives to the importation of a non-native species into North America.
