The birds and the bees – both suffering from pesticide pollution
The ban of neonicotinoids last December may not have gone far enough to prevent damaging effects to the environment. The pesticides were put under restrictive use for three years whilst research was conducted into their ecological impact. Just 7 months in and the evidence against their use is mounting, to add to the pile, two new studies were published this week.
A paper published in the BES Journal of Functional Ecology has found that the neonicotinoid, imidacloprid, impairs foraging behaviour of the bumblebee, Bombus terrestris. Richard Gill and Nigel Raine of Royal Holloway University used Radio-Frequency Identification to track the bees’ movements. Whilst defendants of neonicotinoids insist that that the pesticides are not lethal to pollinators at the levels used, studies like these are important in demonstrating behavioural impacts that can affect the success and survival of bumblebees. Exposure to imidacloprid decreased foraging behaviour efficiency, with bees bringing back smaller pollen loads to the hive, and foraging more frequently in an attempt to compensate for this. Imidacloprid-exposed bees were also unable to exhibit any experience-based improvement in their foraging activity as the control bees did.
Insect pollinators are responsible for the pollination of about 75% of agricultural crops, so the economic importance of the ecosystem service they provide does not go unnoticed. Defra’s consultation for a National Pollinator Strategy is now closed, but it looked at addressing research gaps in the impacts of pesticides, climate change and invasive species on pollinators. This new strategy is due to be published this summer. In 2009 nine research projects were jointly funded £10million by the Living With Environmental Change (LWEC) partnership as part of the Insect Pollinators Initiative.
Another study, published in Nature from Hans de Kroon in the Netherlands, found pollution of the neonicotinoid, imidacloprid, to be the main cause in the decline of farmland birds. Whilst lots of research has focused on the impact on insects, in particular pollinating insects, this study reveals the cascading effects as the toxin moves up the food chain and the impact of pollution in water. At imidacloprid concentrations of more than 20 nanograms per litre, insectivorous bird populations tended to decline by 3.5 per cent on average annually. The potential impacts on other insectivores are implied but yet to be investigated. This study in the Netherlands was conducted over 7 years and so Kroon and colleagues were able to examine the long term changes and look at multiple possible causes in bird population declines. The UK has not collected data on neonicotinoid pollution and so we can only draw assumptions about the whether imidacloprid has impacted our own farmland bird populations similarly. This highlights the importance of funding long-term studies in the UK, which BES has called for in its response to BIS’s recent consultation ‘Creating the Future: a 2020 vision for science and research’.
The current EU regulation only targets three neonicotinoids, and only bans their use on certain crops. Many hope that compelling evidence like this will make Defra reconsider the way these pesticides are used in the UK.
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