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Pollinator decline

2007 Schools Wikipedia Selection. Related subjects: Environment

   Pollinator decline is based on observations made at the end of the
   twentieth century of the reduction in abundance of pollinators in many
   ecosystems worldwide.

   Pollinators participate in sexual reproduction of many plants, by
   ensuring cross- pollination, essential for some species, or a major
   factor in ensuring genetic diversity for others. Since plants are the
   primary food source 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
   biodiversity conservation 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 management seeks to protect,
   enhance, and augment agricultural pollination.

   For example, feral honeybee populations 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   90% in the past 50 years, except for the Southwest where they have been
   replaced by africanized bees.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 honeybee
   colonies have dropped by about two thirds.

   Monoculture needs 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 of 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 source and
   pollen source throughout the year to build up their hive.

Consequences

   The value of bee pollination in human nutrition and food for wildlife
   is 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 alfalfa
   and clover fed to livestock.

   In 2000 Drs. Roger Morse and Nicholas Calderone of Cornell University,
   attempted to quantify the effects of just one pollinator, the honeybee,
   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 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 US food supply.

Possible explanations for pollinator decline

Pesticide misuse

   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
   worse, because they have no human to move or protect them.

   Bumblebee populations are in very bad shape in cotton-growing areas.
   Bumbles are hit over and over 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 leaves no islands of safety where wild
   insect pollinators can reproduce and repopulate. One such program can
   knock down pollinator populations for several years.

   The Chemlawn philosophy has convinced people that dandelions and clover
   are 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.

   See articles:
     * Imidacloprid effects on bee population
     * Regent

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, acarina mites, 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 clover and
   buckwheat, which were very good for bees have been disappearing. Urban
   and suburban development pave or build over former areas of pollinator
   habitat.

   Clearcut logging, especially when mixed forests are replaced by uniform
   age pine planting, causes serious loss of pollinators, by removing
   hardwood bloom that feeds bees early in the season, and by removing
   hollow trees used by feral honeybees, and dead stubs used by many
   solitary bees.

Nectar corridors

   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 catcus species in southwestern United
   States. Its numbers have severely declined, in part due to disruption
   of the nector corridors that it formerly followed. Other migratory
   pollinators include monarch butterflies and some hummingbirds.

Bee paranoia

   If one runs a search for " carpenter bees" on the Internet, one will
   mostly find information about how to kill these valuable pollinators,
   not how to encourage and use them. This attitude ("Get the bug spray,
   ma, I just saw a bee!") is one of the worst problems our pollinators
   have. The " killer bee" hype has increased this paranoia. Beekeepers
   find increased vandalism of 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 moth species, 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. Have a look at this web
   site -
   http://articles.adsabs.harvard.edu//full/seri/JBAA./0104//0000313.000.h
   tml In 1994 it predicted what we now see is actually happening! When
   will anyone realise the truth of what is happening? Do we have to wait
   until it is too late?

Solutions 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 honey
   crops, but increasingly is for contract pollination 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 alkalai bees in alfalfa pollination and
   bumblebees in greenhouses for tomatoes are used to augment and in some
   cases replace honeybees. 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 honeybees, 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 badly as honeybees.

   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, odour,
   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.

   Retrieved from " http://en.wikipedia.org/wiki/Pollinator_decline"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
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