Science

Pesticide is a buzzkill for bee populations

It is common knowledge that the bee population levels are under threat, but a new study has revealed the effect of pesticides on colonies of bumblebees.

Bees occupy an important role by providing a vital service of pollinating many flowers which are of agricultural use and more obviously being directly responsible for the honey we consume. In addition, they have a vital ecological niche and many wild flowers rely on them for reproduction. Bees provide important services and without them our environment and many of our agricultural crops would suffer.

New research brings to light a ‘missing link’ between the widely used pesticides, known as neonicotinoids, and their harmful effect on the pollination of whole colonies. In a study published in Nature, researchers at The University of Reading exposed bees to various levels of neonicotinoids and measured their ability to pollinate apple trees. It was found that the bees which were exposed to the pesticide visited trees less often as well as collecting less pollen. This meant that pesticide exposed colonies resulted in apples containing a reduction of one third fewer seeds. The number of seeds is an important sign of pollination success and is more valuable to farmers as it is associated with higher quality fruit.

This was the first study examining the effect of pesticides on a colony level, with relevance to pollination services, rather than the effects on individual bees. The findings show that the negative effect of such pesticides results in the impairment of the bee’s ability to provide pollination services which will have downstream effects on the production of staple crop yields and also the functioning of natural ecosystems.

An interesting follow up study would be to look at why the pesticide affected the behaviour of the bees. Other work has shown neonicotinoids affect bees’ memory and ability to learn, which is vital in productive foraging.

Syngenta, the company producing the chemical tested in the study denied the relevance of the study, claiming that the resulting number of apples produced was the same for the exposed bees and control group. Also, they criticised the experimental methods suggesting that the conclusions are only representative of a single experiment, carried out under artificial conditions. However, Prof. Felix Wäckers from Lancaster University whom was not connected to the research said that it could actually be an underestimate as in natural conditions the exposure times of the bees to the pesticide would be greater than in the study, and therefore the effects are greater than those measured.

Indeed, in a separate study, it was found that male worker bees foraging in fields were more likely to die when exposed to the neonicotinoids.

It seems this work points strongly in the direction that the neonicotinoids are adversely affecting a processes which is very much important for commercial and ecological purposes. We must therefore assess whether it is worth continuing the use of such chemicals or add them to the list of EU banned pesticides.

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