تصور عالم من دون نحل وما سبب اختفاء النحل
"If the bee disappeared off the surface of the globe then man would only have four years of life left. No more bees, no more pollination, no more plants, no more animals, no more man."
There is some debate about who actually made this remark. It is often attributed to Albert Einstein and the apocalyptic vision is accepted as an indication of how important honeybees are to the world's agricultural economy. It is estimated a third of the food we eat is pollinated by bees. So it is no wonder the dramatic and unexplained decline in the population of these insects is worrying for everyone, not just the conservationists. Bees are extremely important to the pollination of UK crops, particularly oilseed rape, beans and fruits. In the UK there are estimated to be between 100,000 and 300,000 hives, working out at one hive per square kilometre. A hive may contain up to 50,000 bees and individual bees may visit up to 100 flowers on each trip out from the hive. The value of honey bees' services as pollinators in the European Union has been estimated at around £3 billion per year and in the UK alone, pollination is calculated to be worth about £200m to the national economy.
Many causes have been suggested for the marked decrease in bee populations across the world, including diseases, parasites, reduction in the range of flowers growing wild in the countryside, pesticides, or a combination of them all. Now scientists in the UK and France studied the effects of neonicotinoids, which are used in more than 100 nations on farm crops,such as cereals, oilseed rape and sunflowers and in gardens. Neonicotinoids are the first new class of insecticides to be introduced in the last 50 years and are often applied to seeds before planting. As the plant grows, the pesticide is contained in every part of it, deterring insect pests such as aphids but it also enters the pollen and nectar, which is how it can affect bees and a drop in bee numbers means a drop in crop production. The two independent studies show that even low doses of neonicotinoid pesticides can impair the bees’ navigation abilities, reduce the growth of bee colonies and reduce the number of new queens produced.A team from the University of Stirling and Lancaster University, UK found that the neonicotinoid imidacloprid caused an 85% drop in queen production in wild bees and a reduced growth in colony size. While researchers at the National Institute for Agricultural research, Avignon, France found that when honey bees were exposed to another neonicotinoid thiamethoxam then the behavior of bees was impaired. There was a significant reduction in the numbers of worker bees returning to a colony where the bees had been exposed to the neonicotinoid and the growth of colonies was reduced. Researchers in Massachussetts have also found that repeated exposure of bees to low doses of the pesticides leads to colony collapse disorder and the loss of bees. In fact, 94 percent of hives whose bees had been fed the pesticide died off entirely within less than six months. Mites and viruses that they transmit have previously been thought to be responsible for loss of bee colonies but this new research is pointing the finger well and truly at the use of pesticides worldwide.
As the loss of bees continues to rise, countries in Europe, e.g. France, have banned the use of the insecticides while others such as the UK are considering doing so. In the USA the loss of bees is also causing grave concern and authorities in the agriculture dependant states are reconsidering the use of neonicotinoids.
But honeybee populations are declining around the world and so far there seems to be only one other way of pollinating mass numbers of plants. It involves employing people to go round with feather dusters, brushing the insides of plants with pollen.
They are already doing it in parts of China to pollinate pear trees in areas where the insects are extinct. Reading University is currently trying to work out how feasible it would be to employ people to hand pollinate plants in the UK.
They are focusing on how much an apple would cost if you paid someone earning the minimum wage. Early estimates suggest it would more than double the price.
When you consider a single hive of fifty thousand honeybees pollinate half a million plants in one day it is clearly not a practical solution.