The reduction of varieties of flowers is killing the bees

The puzzle that is the overall decline of the bees are more complicated. The European honey bee (Apis mellifera) and the rest of insects antofilos (who love the flowers) already had to fight against the virus of the deformed wings, the fungus Nosema ceranae, the parasite Varroa destructor, sophisticated insecticides as neonicotinoids or own global warming. Now, a study adds an enemy more: the reduction in the diversity of plants and flowering trees caused by modern agriculture.

The Netherlands is one of the regions of the world where more has advanced agriculture. The 80% of the territory that was natural in the beginning of last century today is cultivated land. For this reason, it is a great real-world scenario to study the impact that modern agriculture is having on the bees. Traditional allies of the farmers, these insect pollinators are disappearing at a rate that alarm to these, but also to scientists.

"The negative effects of varroa, the diseases or the burden of pesticides can be reinforced by a limitation of the availability of food," says ecologist at the University of Wageningen and co-author of the study, Jeroen Scheper. "To be in worst conditions by a scenario of scarce resources, honeybees can be more vulnerable to these threats. And the mechanism may operate in reverse: non-lethal effects of pesticides can adversely affect the efficiency of forage worker bees, which could have a greater impact when the availability of floral resources is low," he adds.

"Pollen is a food resource critical to the larvae of bees, but do not develop with the pollen of all species of plants. Some species of bees only grow with the pollen of a single genus or family, while other species harvested from a wide variety of vegetation. But even in this case, the bees have preferences for certain taxa and develop less with the varieties less the attract", explains Scheper. "On the contrary, the bees are less demanding with the nectar, i.e. the species that collect pollen from a single plant variety also collect nectar from many other plant varieties," he adds.

When comparing with the pollen of the dissected insects, the researchers found that the current species that are at a greater decline are precisely those that feed on flowers of wild plants or aim that now are scarce, as some varieties of legumes (pulses) cultivated as forage for livestock or as a technique of fallow in the past.

However, their study, recently published in the journal PNAS, also points out that those species of bees specialized in the rosaceae family instead of dropping down, have proliferated. In addition to the roses, this plant family includes a wide variety of flowers, fruit trees and many other ornamental plants of which the Netherlands are an export powerhouse.