European scientists have discovered how honeybees depopulation is directly related to the exposure of colonies to low doses of insecticides, as they have a higher risk of dying from infection by Nosema ceranae (N. ceranae). These findings support the theory that combining more N. ceranae with a high pesticide content in beehives could contribute to colony depopulation.

European researchers show how the interaction between Nosema ceranae disease and insecticides generates another risk for bee populations, and could be the missing link to helping us understand why an increasing number of bees are dying. The study also highlights how insecticide doses considered to be non-lethal have a lethal toxic potential for organisms that are infested with parasites, thus making bees a lot more vulnerable.

During the research, scientists chronically exposed newly emerged honeybees, of which some were healthy and others were infected with N. ceranae, to low doses of insecticides. According to them, the infected bees died when they were chronically exposed to insecticides. Sublethal doses did not protect those bees either. The synergy is not contingent on the type of insecticide since the two active ingredients assessed in the study - fipronil and thiacloprid - are part of different groups. But experts have been unable to identify the mechanism that enables this synergy.

Experts and laypersons recognise how important a role bees play in our environment, particularly on the sound functioning of the planet's ecosystems and agricultural productivity. The health of the beekeeping sector is a sensitive issue given the fundamental role of bees for pollination, for that reason the European Commission approved the national programmes to improve the production and marketing of apiculture products for the period 2011-2013.