LONDON Rapeseed production is likely to fall in the European Union, top grower of the oilseed, from the 2015 harvest after the bloc voted to protect bees by banning three of the most widely used pesticides.
The EU has decided to restrict from December 1 the use of a class of pesticides known as that neonicotinoids, which have been linked to a plunge in the bee population.
Rapeseed is one of the crops most at risk because of the wide use of neonicotinoids as seed treatments and the fact that alternatives are less effective.
"We are facing the danger of substantial loss of rapeseed crop yields, but it is not possible to say precisely what," said Manuela Specht, spokeswoman for German oilseeds industry association UFOP.
Specht said it was impossible to estimate the extent of losses as the level of insect infestation can vary from year to year, adding that some farmers may decide in several years that rapeseed is too risky and switch to another crop.
The European Union produced 19.3 million metric tons (21.28 million tons) of rapeseed out of the global total of 60.7 million metric tons, including the cultivated variety canola, in the 2012/13 season.
Entomologists said the flea beetle is among the pests most likely to pose a growing threat to EU rapeseed crops.
The small jumping beetle devours the leaves of rapeseed plants and has been known to cause severe damage to crops in both Europe and North America.
The threat posed can vary from year to year. Some of the worst outbreaks in the past have occurred after a hot summer as the beetles lay more eggs in warm weather.
"The major use of neonicotinoids in the UK affected by these changes will be oilseed rape seed treatments. There are currently no seed dressing alternatives to the three banned actives," entomologists at crop consultants ADAS said.
The alternative would be to use foliar pyrethroid sprays to control flea beetles, ADAS said in an emailed comment.
"They (sprayed crop chemicals) don't offer the same flexibility as seed treatments," Jean-Charles Bocquet, director of French crop protection makers association UIPP.
"There are farmers who can't apply them because it is raining or it is windy. In the autumn it rains a lot, so the tractor can't always get into the field."
Another threat is peach potato aphids, which spread the damaging Turnip yellows virus and can cause yield losses of up to 30 percent in rapeseed.
"Control of the peach potato aphid may be more difficult in view of the widespread resistance of this pest to insecticides, including pyrethroids," ADAS said.
European Commission spokesman Roger Waite said the size of the economic damage was difficult to assess and had not been taken into account when the decision was taken.
He added that as a last measure, if no alternative pest control possibilities exist, the legislation provides for the possibility for member states to grant an emergency authorization for restricted use for the pesticides.
"In addition, the actual bans may push the industry to offer suitable alternative solutions," he added.
Some EU countries have already taken some measures against neonicotinoids, including France which withdrew its license for a rapeseed treatment called Cruiser in late June 2012.
The banned neonicotinoids are produced mainly by Germany's Bayer and Switzerland's Syngenta, while rival firms such as Dow Chemical could benefit from increased sales of sprays.
(Additional reporting by Charlie Dunmore in Brussels, Michael Hogan in Hamburg and Gus Trompiz in Paris; editing by Jane Baird)