新型真菌隨人類行為擴散 全球蜜蜂持續消失

The disastrous decline in bees that pollinate most of the world's food crops will continue unless humans profoundly change their ways, warns a United Nations report released today. More than a dozen factors are linked to the worldwide loss of bees, from the disappearance of flowering plants and the use of memory-damaging insecticides to the global spread of pests, air pollution and climate change.

New kinds of virulent fungal pathogens that can be deadly to bees and other pollinators are now showing up worldwide, migrating from one region to another due to shipments linked to globalization and rapidly growing international trade, the report finds.

"Of the 100 crop species that provide 90 percent of the world's food, over 70 are pollinated by bees," said UN Environment Programme Executive Director Achim Steiner today. "The way humanity manages or mismanages its nature-based assets, including pollinators, will in part define our collective future in the 21st century."

Some 20,000 flowering plant species upon which many bee species depend for food could be lost over the coming decades without greater conservation efforts. An Anglo-Dutch study has found that since the 1980s, there has been a 70 percent drop in key wildflowers among them the mint, pea and perennial herb families.

Meanwhile the increasing use of chemicals in agriculture is being found to damage bees, weakening their immune systems, with laboratory studies showing that some insecticides and fungicides can act together to be 1,000 times more toxic to bees.

They can also affect the sense of direction, memory and brain metabolism, and herbicides and pesticides may reduce the availability of plants bees need for food and for the larval stages of some pollinators.

Air pollution, too, may be interfering with the ability of bees to find flowering plants and thus food, with scents that could travel over 800 meters in the 1800s now reaching less than 200 meters from a plant.

Electromagnetic fields from sources such as power lines might also be changing the behavior of bees who are sensitive as they have small abdominal crystals that contain lead.

Another factor concerns parasites and pests, such as the Varroa mite which feeds on bee fluids, and the small hive beetle, which damages honeycombs, stored honey and pollen. Endemic to sub-Saharan Africa, it has spread to North America and Australia and is expected to reach Europe.

Bees may also be suffering from competition by alien species such as the Africanized bee in the United States and the Asian hornet which feed on European honey bees.

Looming over all this is climate change which, left unaddressed, may aggravate the situation in various ways, including by changing the flowering times of plants and shifting rainfall patterns, in turn affecting the quality and quantity of nectar supplies.

"Human beings have fabricated the illusion that in the 21st century they have the technological prowess to be independent of nature. Bees underline the reality that we are more, not less, dependent on nature's services in a world of close to seven billion people," Steiner said, calling on the world to factor in the often invisible multi-trillion dollar services provided by nature.

As the world prepares for Rio+20, the meeting in Rio de Janeiro, Brazil, next year marking the 20th anniversary of the Rio Earth Summit, Steiner called for investment and re-investment in nature-based services, "including pollination from insects such as bees."