The world of pollinators is extremely vast and includes very different animals. Pollinators are not just bees: in addition to the over 20,000 species of honeybees and solitary bees, several species of hymenoptera (e.g. wasps) are pollinators, together with butterflies, hoverflies and beetles, such as ladybugs, beetles, beetles and flies. Many other insects, such as mites and spiders, are considered pollinators, and also some birds and mammals are considered to contribute to pollination.
By wild pollinators we mean all the species of insects that in nature move from flower to flower in search of pollen and nectar, unconsciously allowing one of the most important processes for life on earth: the reproduction of plants. Most insect pollinators are wild species, but some are reared for their economic value. This is the case of honey bees (Apis mellifera).
Mankind has always focused on developing more and more efficient beekeeping techniques, with the aim of achieving maximum results in terms of profit from the breeding of honey bees. At the same time, humans were progressively dismissing attention for the unmanaged populations, which are now decreasing or in danger of extinction.
In 2016, the global assessment of the status of pollinators showed that wild pollinators are decreasing under the increasing threat from human activity, including climate change. According to the same report, the main causes of the decline include biodiversity loss due to the transition of many lands to intensive agriculture and the consequent use of polluting chemical products.
A specific case of a threatened pollinator, when not managed by humans, is represented by bumblebee (Bombus). The approximately 250 known species of bumble bee are mostly found in temperate regions of the northern hemisphere. Nevertheless, these regions are experiencing a dramatic decline in the number of wild individuals.
At the same time, bumble bees are increasingly used by man in intensive agriculture, especially in greenhouse crops. Bumble bees are highly valued crop pollinators due to their ability to thermo-regulate, which enables them to forage in cooler temperatures than most other bees, and their relatively large size providing a large surface area for pollen collection. The commercial production of bumble bees led to a boom in their use, but bumble bees appear to be undergoing dramatic declines in range.
Even though it may seem paradoxical, the current situation of the bumble bee population’s decrease has an explanation. The regions mentioned before contain much of the world’s human population and the most intensive agricultural regions. Indeed, the decline of many bumble bee species is likely linked to the biodiversity loss of floral resources and large-scale use of herbicides and pesticides.
A recent study was recently led on the disappearance of specific bumble bee species in the south of England. In this area, three different species of bumble bees (B. humillis, B. ruderatus and B. subterraneus) that forage on clover and other legumes, had their populations curtailed after the foraging plants were steadily replaced by chemical fertilisers.