Researchers from Saint Andrews University claim to have debunked a study by a pesticide manufacturer that found neonicotinoids presented only a low risk to bees.

On Monday, St Andrews researchers said conclusions drawn from the field study, conducted by Swiss agribusiness Syngenta and published in 2013, were “misleading”. The Syngenta study looked at the effects of neonic thiamethoxam on honeybees foraging in oilseed rape and maize crops.

In their analysis, Dr Robert Schick, Professor Jeremy Greenwood and Professor Steve Buckland from the Centre for Research into Ecological and Environmental Modelling (CREEM) said even large and important effects on bees could have been missed in the 2013 field study because it was statistically too small, and that because of this, it can’t really contribute anything useful to the neonicotinoid debate.

The Syngenta study concluded that because the experiments involved so little replication (two cases for oilseed rape and three for maize) a formal analysis of the data “would lack the power to detect anything other than very large treatment effects, and it is clear from a simple inspection of the results that no large treatment effects were present. Therefore a formal statistical analysis was not conducted because this would be potentially misleading”.

The St Andrews team said they believe this is fundamentally wrong because formal statistical analysis is only potentially misleading if the wrong method is used and because the mere inspection of the results is always potentially misleading because it is an entirely subjective procedure.

Responding to the new assessment of the company’s study, a Syngenta spokesperson said the St Andrews team had focused on an argument that the study can’t be used to rule out the possibility of harmful effects on bees, but had failed to acknowledge that it “provides no evidence for an adverse effect either.”

The Syngenta spokesperson highlighted that the 2013 paper was peer reviewed, and that a second post-publication editorial review concluded that it was “A useful addition to scientific literature”. They said, “Importantly, it should be noted that subsequent published honeybee field effect studies conducted with thiamethoxam seed-treated oilseed rape have reported similar conclusions, i.e. a low risk to honeybees under field conditions of use.”

However, St Andrews’ Professor Jeremy Greenwood said, “In order to reach valid conclusions about the results of an experiment such as this, one needs not just to estimate the effect of the treatment but also to measure the precision of the estimate. That is what we have done, using standard statistical techniques.

“What we found was that the estimates of the treatment effects were so imprecise that one could not tell whether the effects were either too small to pose a problem or, in contrast, so large as to be of serious concern. In effect, the experiments were on such a small scale that little useful could be concluded from them.”