Scientists debunk 'misleading' neonicotinoid study on bee health

The economic value of bees on the pollination of commercially grown crops has been estimated at over £200 million a year in the UK alone
The economic value of bees on the pollination of commercially grown crops has been estimated at over £200 million a year in the UK alone

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

A study by global agrochemical company, Syngenta, concluded there was only a low risk to honey bees from pesticides.

The study has since been described as 'misleading' in new research published by scientists at the University of St Andrews.

Pesticides called neonicotinoids may be implicated in losses of honey bees and other pollinators, the scientists say.

The economic value of honey bees and bumble bees on the pollination of commercially grown crops has been estimated at over £200 million a year in the UK alone.

A major study conducted by the Swiss agrochemical company Syngenta on the effects of the neonic thiamethoxam on honey bees in the field concluded that there was only a low risk to honey bees.

'Statistically too small'

However, new research conducted at the Centre for Research into Ecological and Environmental Modelling (CREEM) shows even large and important effects could have been missed because the Syngenta study was statistically too small.

Their findings are published today in the international journal Environmental Sciences Europe.

The Syngenta study involved two experiments: an oilseed rape experiment conducted at two locations and a maize experiment at three locations.

At each location, the experiments used pairs of fields – in one field the crop was treated with thiamethoxam at levels normally used by farmers, in the other field the crop was untreated.

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”.

'Fundamentally wrong'

The St Andrews team 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.

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.”

Some farmers warn that if key pesticides are lost, it would increase production costs, decrease yields and lead to environmental damage.

For example, the loss of the pesticide glyphosate would require 49% more man hours a year for crop establishment, according to environmental consultancy Adas.