But a study by Britain's Food and Environment Research Agency with the University of Exeter says the results of the original research were flawed. Henry's work calculated this would cause a bee colony to collapse completely but Cresswell said the French study seemed to have used an inappropriately low birth rate, underestimating the rate at which colonies can recover from the loss of bees. "They modeled a colony that isn't increasing in size and what we know is that in springtime when oilseed rape is blossoming they increase rapidly," Cresswell told Reuters. Henry said he was "perfectly comfortable" with the new findings, adding in an emailed response to Reuters: "The model we used predicts a major deviation from the expected colony dynamics, rather than a collapse per se." The April paper in Science said exposure to thiamethoxam "causes high mortality due to homing failure at levels that could put a colony at risk of collapse." Syngenta lost a court bid in July to overturn the French ban on Cruiser OSR, which meant the pesticide was not used for rapeseed sowing in August and September. "It's important for us that what we had argued is now supported by a scientific study," Syngenta France spokesman Laurent Peron told Reuters. We are going to use the findings of this study but it's too early to say in what way. The French farm ministry declined to comment. Environmental campaign group Friends of the Earth argued that sales of the pesticide should be halted while any doubt about their impact on bees remained. "Neonicotinoid pesticides cannot be given a clean bill of health until they have been properly tested for their effect on all bees, not just honeybees," said campaigner Paul de Zylva. Cresswell said: "I am definitely not saying that pesticides are harmless to honeybees, but I think everyone wants to make decisions based on sound evidence, and our research shows that the effects of thiamethoxam are not as severe as first thought." Additional reporting by Gus Trompiz in Paris; Editing by Belinda Goldsmith and Pravin Char