The British bee population is decreasing. Of course, there are the usual biological factors to consider - lack of food, space, competition or the appearance of new predators, or a combination of the above.
Bee experts have also speculated at the decline in bee numbers:
1.Disease from mite and virus infections. The varroa mite reached the UK in 1992 and now infests 95% of hives. Untreated bee colonies die in 3 to 4 years and even low populations of mites affects the bees' health. Other notifiable diseases include American Foul Brood and European Foul Brood have all been found in some areas of the UK . http://www.danthegardener.co.uk/why-are-bees-dying.htm
2.Changing weather patterns. Recent wet and cold summers have prevented bees from foraging for food and have affected the time of year that forage plants appear.
3.Loss of Habitat. Flower-rich grasslands in England have declined by 97% over 60 years, with similar losses elsewhere. This has hit the UK 's bumblebees particularly hard. A range of options are available to farmers to create useful habitat but if we can all work together to create a flower-rich countryside, this would help our UK honey bees, bumblebees and other pollinating insects survive.
4.Insecticides. Insecticides used to kill agricultural pests may harm bees if these are applied incorrectly or without care.
We all need to do our part to help save our bees, whether that's by planting bee friendly plants or by supporting the work of the scientists, UK beekeepers and organisations such as the Bumblebee Conservation Trust, who are working hard to try and help the UK's dying bees
Although Dan the Gardener is not giving references to peer reviewed journals, he is giving his experienced opinion on possible causes for the decline of numbers of bees.
I am speculating that there is another cause that has not been considered - microwaves from our communications matrix called TETRA.
IMHO, there is sufficient evidence from Dr Trower and other researchers to suggest that humans are affected by the communication networks which propagate microwave radiation. I am speculating that it is possible that bee reproduction or physiological functions are affected by microwaves and predict that numbers of bees will decline as our communication networks expand and mast numbers increase. http://www.bibliotecapleyades.net/scalar_tech/esp_scalartech22.htm