More worrying news about neonicotinoid insecticides

Whilst I'm still on holiday, today's guest blog comes from David Gibbons, RSPB's Head of Conservation Science. He will tell you about neonics and the impact they have on the domesticated honey bee and wild bumble bees.

An awkwardly-named group of insecticides – the neonicotinoids, or neonics, for short – has been in the news recently, with increasing evidence of their damaging impact on domesticated honey bees and wild bumble bees.

Chemical insecticides are commonly applied to crops by spraying, but this sometimes kills beneficial insects as well as pests. An alternative approach is to ‘dress’ crop seeds with an insecticide before planting. The insecticide becomes distributed systemically throughout the plant, killing only those insects that eat it. Or, at least, that’s the idea. Unfortunately, such systemic insecticides – of which the most widely used are neonics – end up in the pollen and nectar of crop flowers, and can be eaten by pollinators, such as bees. It has been known for a while that honey bees are killed by high concentrations of neonics. In a recent Italian study, for example, honey bees that flew through the dust cloud from the exhaust of a pneumatic seed drill during normal crop sowing operations received a large dose of neonics, and were all killed. What has remained less clear, however, was whether the concentrations that bees would routinely be exposed to in the field were harmful to them or not.

Two new studies have looked at the impact of neonics at field-realistic levels. The first, by researchers from Stirling University, exposed bumble bee colonies in the lab to realistic levels of the neonic imidacloprid, and then reintroduced them into the wild. Colonies treated with imidacloprid produced 85% fewer new queens than those that were not. In a separate French study, honey bees that were treated with realistic doses of a different neonic (thiamethoxam) were much less likely to return to their colony than those that were not; the bees became intoxicated by the neonic, lost their homing ability and died. Both studies suggested that numbers of bees would fall over time at the concentrations used in the experiments.

Bee populations are in decline for a variety of reasons, such as parasites and the loss of flower-rich habitats, but these new studies suggest that neonics may be playing more of a role in honey and bumble bee declines than previously thought.

So what is the RSPB doing about it? We are urging the UK Government to fund further research into the impact of neonics, particularly under field conditions. We are also assisting an IUCN Task Force to review all the available scientific evidence, and to devise an improved way of testing pesticides before they are approved for use. Perhaps, most importantly, we are supporting thousands of farmers in the work they are doing to help wildlife. Such actions are vital to safeguard populations of honey and other bees, and their roles as pollinators of crops and wild flowers.

What are your thoughts on this? It would be great to hear your views.