There are three main different types of bee: honeybees, bumblebees and solitary bees. Honeybees live in large colonies of up to 60,000 workers, they tend to make their nests in the cavities of trees and buildings. They have been domesticated by man and, obviously, make honey! Bumblebees, like honeybees, are also social bees, living in smaller colonies of between 40 and 400 workers. Bumblebees sometimes nest in buildings and trees but also nest underground. Solitary bees live on their own, but do sometimes nest near to others. They, too, make nests in trees, buildings and underground. Whilst honeybees are a single species, there are many species of bumblebees and solitary bee.
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All three types of bee are pollinators. In the UK, 70 crop types are dependent on, or benefit from bee pollination. Globally about a third of all the food we eat depends to some extent on pollination by animals, including bees. It’s estimated crop pollination by animals contributes $170bn to the global agricultural economy. While honeybees are used commercially to pollinate crops, wild bees are also important to crop pollination. Wild bees pollinating alongside honeybees increase the pollination efficiency fivefold. In Brazil there is an example of what can happen if the wild pollinator population drops too low, where passion fruit farming requires labour intensive hand pollination.
As well as food crops, bees are important pollinators for wild plants. There are over 250,000 species of flowering plants and trees. Over half of these rely on insects, mainly bees, to ensure pollination. This makes bees important for biodiversity in general. Managed honeybees aren’t as effective as pollinators as bumblebees and solitary bees (which are up to three times better), so it’s important that there is a diverse selection of wild bees, as well as managed hives.
The number of bee colonies had been in decline since 1945, from 400,000 managed hives to an estimated 275,000 managed hives currently, although the number of beekeepers is thought to have increased slightly in recent years due to the increased coverage of bees in the media. There are 250 wild British bee species, of these, half are either nationally scarce or are on the IUCN Red List of Threatened Species. In Britain in the last century 18 species of solitary bee and two species of bumblebee were lost. General wild bee diversity and distribution have also been in decline, especially amongst specialist bee species. So what’s killing bees?
The intensification of agriculture in the past 50 years has been one of the main causes for bee population decline. Changes in land use have caused the destruction and fragmentation of their natural habitat, e.g. 97% of flower rich meadows in England and Wales have been lost since the 1930s. The use of herbicides causes weeds and plants along the borders of crop fields to die, which are food and home sources for bees. Flood irrigation also causes the drowning of species which nest underground. Honeybee hives have also recently suffered from Colony Collapse Disorder. This is where most of the worker bees leave the colony, causing the remaining colony to die. The causes of this mysterious phenomena are yet unknown, though it’s been linked to mites and pesticide use.
Bees do a lot for us, both for food and for general wildlife, so we should care about their decline and try to prevent it.