- Pollinator decline
The term Pollinator decline refers to the reduction in abundance of
pollinators in many ecosystems worldwide during the end of the twentieth century.
Pollinators participate in sexual reproduction of many
plants, by ensuring cross- pollination, essential for some species, or a major factor in ensuring genetic diversityfor others. Since plants are the primary foodsource for animals, the reduction of one of the primary pollination agents, or even their possible disappearance, has raised concern, and the conservation of pollinators has become part of biodiversityconservation efforts.
Observation of pollinator decline
As plantings have grown larger, the need for concentrated pollinators at bloom time has grown. At the same time populations of many pollinators has been declining, and this decline has become a major environmental issue today.
Pollination managementseeks to protect, enhance, and augment agricultural pollination.
For example, feral
honey beepopulations in the US have dropped about 90% in the past 50 years, except for the Southwest where they have been replaced by Africanized bees. At the same time managed honey bee colonies have dropped by about two thirds. On the other hand, this has been offset by a natural increase in native pollinator populations in parts of the US, where such had been partially displaced by the invasive honey bees imported from Europe. Monocultureneeds very high populations at bloom, but can make the area quite barren, or even toxic when the bloom is done.
The study of pollinator decline is also interesting some scientists, as bees have the potential to become a keystone
indicator speciesof environmental degradation. Any changes in their abundance and diversity will influence the abundance and diversity of the prevailing plant species. This is a mutual dependency as bees rely on a steady nectar sourceand pollen sourcethroughout the year to build up their hive.
The value of bee pollination in human
nutritionand foodfor wildlifeis immense and difficult to quantify.
It is commonly said that about one third of human nutrition is due to bee pollination. This includes the majority of
fruits, many vegetables (or their seed crop) and secondary effects from legumes such as alfalfaand cloverfed to livestock. In the United States, only about 30% of crops utilize honeybees for their pollination, and even among those some of the bee usage is superfluous, native pollinators actually doing the work [http://www.fao.org/ag/AGp/agps/C-CAB/Castudies/pdf/1-002.pdf] .
2000Drs. Roger Morseand Nicholas Calderone of Cornell University, attempted to quantify the effects of just one pollinator, the Western honey bee, on only US food crops. Their calculations came up with a figure of US $14.6 billion in food crop value.
There has not been sufficient study to quantify the effects of pollinator decline on wild plants and wild life that depends on them for feed. Some plants on the endangered species list are endangered because they have lost their normal, native pollinators because of displacement by invasive honey bees. It is important to recognize that
honey bees are not native to the Western Hemisphere, so any loss of honey bees does not represent a threat to native plants; the role of honey bees in the Western Hemisphere is almost exclusively agricultural. To the extent that honey bees compete with native bee species, a decrease in the honey bee population may be beneficial to native plants and pollinators.
Increasing public awareness
The steady increase in beekeeper migration (for pollination service on agricultural crops) has masked the issue of pollinator decline from much public awareness, however sudden blocks to such migration could have catastrophic results on the global food supply.
Possible explanations for pollinator decline
It is a label violation to apply most
insecticides on crops during bloom, or to allow the pesticide to drift to blooming weeds that bees are visiting. Yet such applications are frequently done, with little enforcement of the bee protection directions. Pesticide misuse has driven beekeepers out of business, but can affect native wild bees even more, because they have no human to move or protect them. Bumblebeepopulations are in jeopardy in cotton-growing areas, since they are dosed repeatedly when pesticide applicators apply insecticides on blooming cotton fields while the bees are foraging.
Widespread aerial applications for
mosquitoes, med-flies, grasshoppers, gypsy moths and other insects leave no islands of safety where wild insect pollinators can reproduce and repopulate. One such program can reduce or endanger pollinator populations for several years.
Many homeowners feel that
dandelions and cloverare weeds, that lawns should only be grass, and that they should be highly treated with pesticides. This makes a hostile environment for bees, butterflies and other pollinators.
Imidacloprid effects on bee population
Rapid transfer of
parasites and diseases of pollinator species around the world
Increased international commerce within modern times has moved diseases such as American foulbrood and chalkbrood, and parasites such as
varroa mites, acarinamites, and the small African hive beetle to new areas of the world, causing much loss of bees in the areas where they do not have much resistance to these pests. Imported fire ants have decimated ground nesting bees in wide areas of the southern US.
Loss of habitat and forage
The push to remove hedgerows and other "unproductive" land in some farm areas removes habitat and homes for wild bees. Large tractor mounted rotary mowers may make farms and roadsides look neater, but they remove bee habitat at the same time. Old crops such as
sweet cloverand buckwheat, which were very good for bees have been disappearing. Urban and suburban development pave or build over former areas of pollinator habitat.
logging, especially when mixed forests are replaced by uniform age pineplanting, causes serious loss of pollinators, by removing hardwoodbloom that feeds bees early in the season, and by removing hollow trees used by feral honey bees, and dead stubs used by many solitary bees.
Migratory pollinators require a continuous supply of
nectar sources to gain their energy requirements for the migration. In some areas development or agriculture has disrupted and broken up these traditional corridors, and the pollinators have to find alternative routes or discontinue migration. A good example is the endangered lesser long-nosed bat ("Leptonycteris curasoae") which was formerly the main pollinator of a number of cactus species in southwestern United States. Its numbers have severely declined, in part due to disruption of the nectar corridors that it formerly followed. Other migratory pollinators include monarch butterflies and some hummingbirds.
Bees are often viewed negatively by homeowners and other property owners. A search for "
carpenter bees" on the Internet primarily yields information on removal rather than information regarding bees in a positive light. Recent hysteria regarding killer bees has contributed to these views. Beekeepers find increased vandalismof their hives, more difficulty in finding locations for bee yards, and more people inclined to sue the local beekeeper if they are stung, even if it is by a yellow jacket. Light pollution
Increasing use of outside artificial lights, which interfere with the navigational ability of many
mothspecies, and is suspected of interference with migratory birds may also impact pollination. Moths are important pollinators of night blooming flowers and moth disorientation may reduce or eliminate the plants ability to reproduce, thus leading to long term ecological effects. This is a new field and this environmental issue needs further study.
Threat by invasive honey bees
Many native pollinators decline in population when faced with competition from invasive honey bees. For example, the western honey bee is invasive in the United States, the wild population comprised entirely of feral bees escaped from European bee colonies imported to fertilize non-native, old-world crops. Where
colony collapse disorderreduced invasive honey bee populations in the US, native pollinators sometimes have made recoveries, restored to their natural niche by the loss.
Researchers at the
University of Virginiahave discovered that air pollutionfrom automobiles and power plants has been inhibiting the ability of pollinators such as bees and butterflies to find the fragrances of flowers. Pollutants such as ozone, hydroxyl, and nitrateradicals bond quickly with volatile scent molecules of flowers, which consequently travel shorter distances intact. There results a vicious cyclein which pollinators travel increasingly longer distances to find flowers providing them nectar, and flowers receive inadequate pollinationto reproduce and diversify. [http://www.eurekalert.org/pub_releases/2008-04/uov-ffd041008.php]
olutions to pollinator decline
The decline of pollinators is compensated to some extent by beekeepers becoming migratory, following the bloom northward in the spring from southern wintering locations. Migration may be for traditional
honeycrops, but increasingly is for contractpollination to supply the needs for growers of crops that require it.
Conservation and restoration efforts
Efforts are being made to sustain pollinator diversity in agro- and natural eco-systems by some environmental groups. Prairie restoration, establishment of wildlife preserves, and encouragement of diverse wildlife landscaping rather than monoculture lawns, are examples of ways to help pollinators.
Use of alternative pollinators
Honey bees are usually the most widely chosen insects in most managed pollination situations. However they are not the most efficient pollinators of some flowers. Alternative pollinators, such as for example, leafcutter and
alkali bees in alfalfa pollination and bumblebees in greenhouses for tomatoes are used to augment and in some cases replace honey bees. A wide variety of other bees can be found in the environment that are specialist pollinators (some only using one plant species). However, most of these alternative insects' value as pollinators and their relationships with plants are as yet little known.
In the US, some think that other pollinators will in time replace the lost honey bees, blamed on introduced acarine and varroa mites, but general pollinator decline was already happening before these entered the picture. Only in a few areas are wild populations of pollinators building up; in most areas they are declining as quickly as honey bees.
Furthermore pollinators cannot be exchanged on a one-for-one basis. They are not all equal. Some are generalists, some are specialists. Some are brawny; some are feeble. Some have long tongues; some short. Some work at colder temperatures than others. Bees may deliberately collect pollen, but have different collection techniques, which can greatly affect their efficiency as pollinators.
Flowers are frequently specifically adapted to one pollinator, or a small group of pollinators because of floral structure, color, odor, nectar guides, etc. Proposed alternative pollinators may not be physically capable of accomplishing pollination, or they may not be attracted to the flower of that plant species, or they may rob nectar by cutting sepals, thus avoiding pollination. Understanding the pollination needs of a species is vital to understanding of a plant species, yet this is often poorly understood. In horticulture it is critical to the economic success of the grower, and crops have sometimes been abandoned from general use in an area because of lack of understanding of pollinator needs.
Bees and toxic chemicals
Colony Collapse Disorder
Diseases of the honey bee
Pesticide toxicity to bees
Imidacloprid effects on bee population
*"The Value of Honey Bees As Pollinators of U.S. Crops in 2000", Drs.
Roger Morseand Nicholas Calderone of Cornell University(2000) : [http://www.masterbeekeeper.org/pdf/pollination.pdf]
* "The Forgotten Pollinators" by Drs. Stephen L. Buchmann and
Gary Paul Nabhanis a classic work describing the pollinator crisis. In the vein of Rachel Carson, their opening chapter, "Silent Spring and Fruitless Falls" describes the risk in a nutshell. They go on to illustrate the problem and propose some solutions.
* "Pollination, the Forgotten Agricultural Input", Dr. Malcolm Sanford of the
University of Florida, published in Proceedings of the Florida Agricultural Conference and Trade Show, Lakeland, FL, September 29-30, 1998, J. Ferguson, et al eds., pp. 45-47. [http://apis.ifas.ufl.edu/papers/altpol.htm]
* "Biological Diversity: Pollinators" Science in Africa, Issue 2, Sun Jul 30 2006
United Nations Food and Agriculture Organizationposition paper on the subject of pollinator decline: [http://www.scienceinafrica.co.za/pollinator.htm]
*"The International Initiative for the Conservation and Sustainable use of Pollinators: A proposal for a plan of action" Convention on biological diversity, Montreal, 12-16 November 2001, [http://www.biodiv.org/doc/meetings/sbstta/sbstta-07/official/sbstta-07-09-add1-en.doc]
Xerces SocietyPollinator Conservation Program" 2006 (North America) [http://www.xerces.org/Pollinator_Insect_Conservation/index.htm]
*"POLLINATOR BIODIVERSITY A CO-ORDINATED GLOBAL APPROACH", Eardley, C. 2001. Acta Hort. (ISHS) 561:331-332(
FAO) VIII International Symposium on Pollination - Pollination: Integrator of Crops and Native Plant Systems [http://www.actahort.org/books/561/561_50.htm]
*"The Economic Impacts of Pollinator Declines: An Approach to Assessing the Consequences", Peter G. Kevan and Truman P. Phillips,
Conservation Ecologyv.5, i.1 June 2001 [http://www.mindfully.org/Farm/Pollinator-Declines.htm]
*"Brazilian Pollinators Initiative", Vera Lucia Imperatriz Fonseca; Braulio Ferreira Souza Dias [http://eco.ib.usp.br/beelab/bpi_ceara.pdf] accessed March 2004 "THE SAO PAULO DECLARATION ON POLLINATORS" [http://rgm.fmrp.usp.br/beescience/arquivospdf/workshop.pdf]
*"The Pollination Home Page" [http://pollinator.com] US; accessed Jul 2006
*"The North America Pollinator Protection Campaign" [http://www.nappc.org/]
Coevolution InstituteUS; accessed Jul 2006
*"Pollinator Conservation Handbook" Xerces Society 2005, [http://www.xerces.org/pubs_merch/PCH.htm]
*"The Bumblebee Conservation Trust" [http://www.bumblebeeconservationtrust.co.uk/] Great Britain; accessed Jul 2006
*"The impact of aerial fenitrothion spraying upon the population biology of bumble bees (Bombus Latr.: Hym.) in southwestern
New Brunswick". Plowright, R.C., B.A. Pendrel and I.A. McLaren. 1978. Canadian Entomology 110: 1145-1156. - A case study in the loss of pollination for blueberries, caused by gypsy moth spraying, which also killed bumblebees
Wikimedia Foundation. 2010.
Look at other dictionaries:
Pollinator — A pollinator is the biotic agent (vector) that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the… … Wikipedia
North American Pollinator Protection Campaign — The North American Pollinator Protection Campaign (NAPPC) is a multifaceted organization of academics, government officials, policy makers, and industry stakeholders working towards pollinator conservation in North America. NAPPC works in… … Wikipedia
Pollination — Carpenter bee with pollen collected from Night blooming cereus … Wikipedia
Colony Collapse Disorder — (or CCD) is a phenomenon in which worker bees from a beehive or Western honey bee colony abruptly disappear. While such disappearances have occurred throughout the history of apiculture, the term Colony Collapse Disorder was first applied to a… … Wikipedia
Pollination management — is the label for horticultural practices that accomplish or enhance pollination of a crop, to improve yield or quality, by understanding of the particular crop s pollination needs, and by knowledgeable management of pollenizers, pollinators, and… … Wikipedia
Colony collapse disorder — Honey bees entering a beehive Colony collapse disorder (CCD) is a phenomenon in which worker bees from a beehive or European honey bee colony abruptly disappear. While such disappearances have occurred throughout the history of apiculture, the… … Wikipedia
Pollination syndrome — Baltimore (Euphydryas phaeton) nectaring at daisy (Argyranthemum) Pollination syndromes are suites of flower traits that have evolved in response to natural selection imposed by different pollen vectors, which can be abiotic (wind and water) or… … Wikipedia
Insecticide — For other uses, see Insecticide (disambiguation). An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine,… … Wikipedia
Gary Paul Nabhan — Infobox Scientist box width = name = Gary Paul Nabhan image width = caption = birth date = March 17, 1952 birth place = Gary, Indiana death date = death place = residence = citizenship = nationality = ethnicity = Lebanese American fields =… … Wikipedia
Hand pollination — (also called mechanical pollination ) is a technique used when natural, or open pollination is insufficient or undesirable. The most common techniques are for crops such as cucurbits, which may exhibit poor pollination by fruit abortion, fruit… … Wikipedia