Which way? Neonicotinoid pesticides can disrupt bee navigation (Image: Zhang Bo/Getty)

A worldwide dispute over the threat to bees posed by the class of pesticides called neonicotinoids, took a dramatic new turn last week, when a US court overturned federal approval for a new formulation called sulfoxaflor. Judges found that the Environmental Protection Agency (EPA) had relied on “flawed and limited” data, and its green light was unjustified given the “precariousness of bee populations”.

As a result of the US decisions, rules on the controversial chemicals in the US and European Union are in bizarre contradiction. The US has approved most neonicotinoids while now banning sulfoxaflor.


But the EU has banned most neonicotinoids for use on flowering crops and spring sown crops since 2013, but approved sulfoxaflor in July on the basis that it would not have any unacceptable effects on the environment. “The public will be justifiably confused and concerned,” says Matt Shardlow, CEO of Buglife, a British group that campaigns against neonicotinoids.

The US ruling against sulfoxaflor, which is manufactured by Dow AgroSciences, was made by a federal appeals court in San Francisco and applies nationally. The court found that, in granting approval for sulfoxaflor in 2013, the agency had violated its own rules on obtaining safety information, and should collect more data on its effects on bees before granting approval for its use.

Circuit judge Randy Smith said: “I am inclined to believe the EPA… decided to register sulfoxaflor unconditionally in response to public pressure for the product and attempted to support its decision retrospectively with studies it had previously found inadequate.”

Dow, which says the chemical has a multibillion dollar market, said it would seek to overturn the ruling by undertaking “additional regulatory work”. The EPA did not comment, but has previously argued that, while sulfoxaflor is toxic to bees, “the key is to limit exposure” by not spraying crops at a time when they attract bees.

Environmentalists and bee-keepers’ associations who brought the action believe the ruling could turn the tide against neonicotinoids in general. Campaigners told New Scientist that the same criticisms of the quality of research highlighted by the court applied to the three other neonicotinoid pesticides: clothianidin, thiamethoxam and imidacloprid.

Neonicotinoids have grown popular for protecting fruit, vegetables and arable crops against boring and biting pests, including aphids and beetles. But they have been widely accused of harming bees and other pollinators by disrupting their navigation systems, with major impacts on the survival of colonies. The US court found that the EPA, after initially asking Dow for more studies on these sub-lethal effects, eventually granted approval for the pesticides without them.

The EU banned most neonicotinoids in 2013, citing concerns for bees raised by its scientific watchdog, the European Food Standards Authority. But, under pressure from manufacturers, Europe last month approved sulfoxaflor, while leaving final decisions on its use to national regulators. This despite the EFSA advising that “missing information” about sulfoxaflor meant that “a high risk to bees was not excluded”. Meanwhile, a review of the wider ban on neonicotinoids begins this autumn.

The UK suspended the EU ban on neonicotinoids in some parts of the country in July, so the pesticides could be used on oilseed rape crops.