Imidacloprid linked to French bee deaths  

French beekeepers consider the insecticide imidacloprid possibly provides an explanation for the drastic decline in the bee population since 1993. Honey production has fallen by some 60 per cent in the affected area. 
    Many farmers were puzzled that the bees were not making it home to their hives and noted that this coincided with the period when sunflowers started blooming. Only those insects collecting nectar from sunflowers seemed to be affected. Sunflower cultivation increased rapidly from 37,000 ha. in 1978 to a million ha. in 1990 especially in central, central-west and south-west France, the same areas where beekeepers report losses.
    Since 1993, seeds have been treated with the insecticide Gaucho (containing imidacloprid) to protect against aphids. A Ministry of Agriculture's report notes that analysis of bees in the field and on the capitula of sunflowers found imidacloprid residues of 0.09 mg/kg in the capitula and 0.35 mg/kg on the bees. The makers of Gaucho, Bayer, have denied that it is responsible for the problem. The Ministry of Agriculture concluded that the company has not established that its product is not to blame. However, it also says that local beekeeper reports do not constitute sufficient evidence to be able to conclude that Gaucho is causing the problem. An urgent investigation has been launched, funded by the European Community, the French government and Bayer, which has agreed to cover five per cent of the costs.
    Some beekeepers using Gaucho have not had problems and other hypotheses have been put forward including the possible synergy between imidacloprid and other pesticides such as fungicides, insecticides or acaracides applied in the vicinity.

Luc P Belzunces and Jean-Noël Tasei, Rapport sur les effets des traitements de semences de tournesol au Gaucho (imidaclopride), Ministere de l'Agriculture, 11 December 1997.

[This article first appeared in Pesticides News No. 40, June 1998, page 17]