Published September 13, 2012

Water droplets produced by corn plants which seeds were treated with systemic insecticides can kill bees in a few minutes from what demonstrates a research at the University of Padua in Italy.


Although the AFSSA (the French Agency for Food Safety) does not explicitly denounce the role of phytosanitary treatments in the disappearance of bees in its latest report on the subject, it seems difficult today to deny their deleterious effects.

But so far, we had only evaluated the effect of pesticides on bees when the pesticide-coated seeds are sown in the fields, or by measuring the contamination of pollen and nectar by pesticides that have been distributed in each cell of the plant which seed has been treated systemically.

Today we find that the effects of systemic insecticides are likely to be much larger that was estimated previously.

For the Professor Vincenzo Girolami of the Department of Environmental Agronomy and plant production from the University of Padua, the water drops from the phenomenon of guttation (1) of plants from treated maize seeds kill in a few minutes the bees that have absorbed the product. His chemist colleague Andrea Tapparo showed by analyzing the drops from the « sweating » of the leaves, that they could contain neonicotinoids (the substances used in the treatment of seeds) at concentrations 10,000 times higher than the lethal dose to bees.

The droplets, which are based on the surface of the leaves are among the preferred sources of water for bees, they risk a direct poisoning, and for Italian beekeepers, the problem will not be solved by simply improving seeders or processing techniques.

For more information:

1- On the surface, guttation looks like dew. It is a phenomenon near sweating that some plants such as corn implement to remove the excess pressure from the roots that may appear during the night, especially in soils where the soil moisture is important. It results in a form of water seepage at the level of the stomata (leaves pores), which condenses to form droplets on the leaves.