Here, I relate what the journalist said in his article « Le déclin massif des abeilles est en voie d’élucidation ». All quotes, originally in French, were translated by me.
This article starts from an observation: “Massive mortalities of honey bees have been reported all over the world – mainly in the United States and Europe”. This would be “all the more worrying given that about a third of the food consumed globally relies on crop pollination, of which bees are the main agent. “
According to a study published by PloS One (Vidau et al. 2011), a combination of exposure to insecticides and natural parasites is “arguably the cause of the decline”.
It observed that exposure to very low doses (of the order of 1% of the LD50) of fipronil and thiacloprid did not cause significant mortality on its own. However, it proved to be lethal for 70% and 80% respectively of bees infected with a common intestinal parasite, Nosema ceranae, which, alone, causes limited mortality.
This would be proof of a “cocktail effect” and “could lead to a review of the authorizations of phytosanitary molecules.”