Mass deaths of bee colonies in many parts of the world may be part of a wider, hidden threat to wild insect pollinators vital to human food supplies, a UN study found today.
Declines in flowering plants, a spread of parasites, use of pesticides or air pollution were among more than a dozen factors behind recent collapses of bee colonies mainly in North America and Europe, the UN Environment Programme (UNEP) said.
The report said bees were crucial to food supplies, with more than 70 of the 100 crop species that provide 90 per cent of the world's food pollinated by them.
That cocktail of problems - rather than a single cause killing bees in hives that might be easier to fix - may also threaten wild bees and other insects vital to pollinate crops such as soybeans, potatoes or apple trees.
"It's the tip of the iceberg we're seeing with the honey bees," said Peter Neumann, a lead author of the study of global honey bee colony disorders and other threats to insect pollinators.
"There is not an immediate pollination disaster but the writing is on the wall," said Dr Neumann, of the Swiss Bee Research Centre. "We have to do something to ensure pollination for future generations. There are some indicators that it is becoming a global issue."
Dr Neumann said man-made colonies are increasingly vulnerable to decline and collapse as a result of a variety of factors. Declines in managed bee colonies have accelerated since 1998 in the UK and other European countries in recent years, while North America, China, Japan and Egypt have all suffered losses of bee colonies.
The study warned that more than a dozen factors could be behind the collapses in bee colonies, including the loss of flowering plant species that provide food for bees - a problem which could become worse as the climate
changes. Diseases and pests, including the spread of the damaging small hive beetle from Africa towards Europe, also threaten bee colonies.
Alien species of insect including the Asian hornet could be damaging honeybee populations in Europe, the report warned, while air pollution could be interfering with scents which help them find food.
Herbicides and pesticides may be reducing the amount of wildflowers as well as weakening honeybees' immune systems or affecting brain activity and their sense of direction and memory. The report even warns that electromagnetic fields from power lines could be changing bees' behaviour.
Dr Neumann urged more research into insects, noting that charismatic animals such as polar bears won most attention as victims of global warming. "Insects are usually not cute but they are the backbone of ecosystems," he said.
Bees and other pollinators such as butterflies, beetles or birds are estimated to do work worth €153 billion a year to the human economy - about 9.5 per cent of the total value of human food production, the report said. Recent estimates of the contribution by managed species, mainly honey bees, range up to €57 billion. In the United States, over two million bee colonies are trucked around the country to help pollination every year.
Agencies