Comment: New study reveals pesticide combination affects bees’ ability to learn
27 March 2013
A new study published today (27th March) has found exposure to a combination of pesticides (including neonicotinoids) negatively affects the brains of bees. The study is the first to show ‘field relevant’ levels of these pesticides have a direct impact on pollinator brain physiology.
Researchers used levels of pesticides that bees experience in the wild and discovered that information flow in bee’s brains was affected. They also found that bees exposed to combined pesticides were slower to learn or completely forgot important associations between floral scent and food rewards.
The numbers of honey bees, bumble bees and other pollinating insects are declining rapidly and there is strong evidence that intensive farming practices and in particular certain pesticides are key culprits. They play a crucial role in pollinating crops and the cost of losing pollinating insects has been calculated to be £1.8 billion to UK farmers.
Emma Hockridge, Soil Association head of policy said;
“We welcome this new research which provides new insight into the effects of pesticides on honey bee brain function. This follows a number of other studies which also highlight the dangers of neonicotinoid pesticides on pollinators. It further highlights the need to get off the chemical treadmill and focus on alternative ways of controlling insect pests, for example by using agroecological approaches such as organic farming.”
One of the authors of the study, Dr Christopher Connolly, University of Dundee said:
“This study shows for the first time the effect of field-relevant concentrations (3 ppb) of neonicotinoid pesticides and an organophosphate miticide on honeybee brain function. Both prevent information flow in the major learning centre of the honeybee brain. There is clearly a major brain dysfunction in response to these compounds and this is supported by behavioural research from Newcastle University (Wright study 2013). Similarly, local honeybee losses in Scotland have been 2-fold higher in bees reported to forage on oilseed rape, the major exposure risk of the neonicotinoids to bees. Unfortunately, the negative impact is increased when the chemicals are present together. This highlights the urgent need for the recording of local pesticide use, so that potentially dangerous combinations of pesticides may be identified by association with localised bee losses. Sadly, although this pesticide use is recorded by farmers, the UK government does not collect this data.
“We believe that targeting the insect brain is a high risk strategy to control crop pests as toxicity at non-target insects seems inevitable. We need to develop alternative strategies to using neonicotinoids and other insecticides to address this problem, for example by encouraging agro-ecological farming systems and creating a network of garden nature reserves free of pesticides and filled with pollinator friendly plants and nesting sites.”
Following yesterday’s announcement from Farm Minister David Heath who said that Defra UK field trials had not conclusively found evidence of a link between neonicotinoid use and bee deaths, Emma Hockridge of the Soil Association said;
“We look forward to seeing the detail of the results of these field trials. David Heath only referred to the impact of colony growth in bumble bees in the research mentioned and didn’t rule out the impacts of neonicotinoids. Defra is relying on limited trials, rather than a whole range of studies which are showing harm to bees. As we continue to see consistent evidence signalling neonicotinoids should be banned, we call on the UK Government to vote to ban a number of neonicotinoid pesticides as is currently being discussed in the EU.”