Insects and Insecticides

 Written evidence submitted by Professor Dave Goulson, University of Stirling.

Insecticides

· I write with regard to the possible role of neonicotinoid pesticides in harming bee health, and other potential impacts on the environment. This class of compounds are widely used in the UK (1.3 million ha treated in 2010) and worldwide, mainly as a seed coating. They are absorbed by the growing crop and protect it against herbivorous insects. Concern has focused on the impact of neonicotinoids in the pollen and nectar of crops such as oilseed rape and sunflowers, which are consumed by both honeybees and wild bees such as bumblebees.

· I am an academic with 20 years’ experience in studies of ecology, biodiversity and conservation, with a particular focus on bumblebees. I am author of a recent study on the impacts of neonicotinoid insecticides on bumblebees, published in Science in March 2012, which has been much-quoted during the recent controversy over insecticides (Whitehorn et al. 2012).

· Firstly, I would like to flag up my willingness to discuss any aspect of this study, and its implications, should this be useful.

· I am concerned that Defra’s response to this work, and other studies, seems to be focused on trying to pick small holes and then using them as a justification for inaction. No study is perfect, and in practice it is impossible to carry out the ideal study. I would be happy to explain this in detail, but in essence a proper experiment requires natural, free flying bees in multiple areas with and without neonicotinoids. There are not areas without neonicotinoids in Europe. Hence if Defra are waiting for the perfect experiment to be performed, they will be waiting a very long time.

· There are major knowledge gaps which require further study. When neonicotinoids were first introduced for application as a seed dressing (rather than an aerial spray), they were welcomed as this was assumed to give better targeting of the crop and reduced environmental damage. However, this may not be the case, for the following reasons:

A) Published research by Bayer’s scientists suggests that about 2% of neonicotinoid seed dressings are absorbed by the crop, leaving the fate of 98% unknown. These compounds are water soluble, and degrade very slowly in soil water. If they are drawn up by non-target vegetation, such as hedgerow shrubs, they could impact directly on numerous insects such as butterfly larvae. There appears to be just one study of levels in non-target plants, from the US, which found concentrations of neonicotinoid sufficient to kill herbivorous insects in dandelions growing near treated crops (Krupke et al. 2012, PlosONE). We do not know whether farmland vegetation in the UK is similarly contaminated.

B) Recent studies from Italy suggest that, no matter how carefully dressed seeds are drilled, neonicotinoid dust is created, sufficient to deliver lethal doses to flying insects nearby and presumably able to drift into non-target vegetation (Tapparo et al. 2012; Marzaro et al. 2011).

It seems to me that there is an urgent need to establish the fate of the 98% of neonicotinoids which are not in the crop, and to find out what impacts they might be having on the environment. Funding permitting, I am currently attempting to pursue this line of research.

26 September 2012

Prepared 5th November 2012