Insects and Insecticides

Further supplementary written evidence submitted by Lord de Mauley, Parliamentary Under Secretary of State, Department for Environment, Food and Rural Affairs

OUTLINE DESCRIPTION OF DEFRA PROJECT PS2371

EFFECTS OF NEONICOTINOID SEED TREATMENTS ON BUMBLE BEE COLONIES UNDER FIELD CONDITIONS

Project set-up

§ The project was carried out by the Food and Environment Research Agency;

§ Experiments were carried out on bumble bees at three sites (A, B and C) in Northern England;

§ 20 bumble bee colonies were established at each site;

§ The end points of the experiments were (1) mass of colonies after a set period of time; and (2) number of queens produced

§ Pollen samples were taken from bumblebee foragers. Pollen and nectar were collected using a honey bee colony at each site.

Results

§ The neonicotinoid thiamethoxam was the most abundant residue in pollen and nectar from colonies at sites A and B. This neonicotinoid was not part of the experiment at all. It would therefore appear either that some of the seed at the "control" site had been treated with this, or that the bees had been foraging on fields (other than the experimental sites) which had this treatment;

§ Bumble bee colonies at all three sites survived, grew and produced queens;

§ There was no significant difference in the number of queens produced between the sites;

§ There was no significant difference between the terminal mass of colonies at sites A and B. The colonies at site C had a significantly lower terminal mass than the other two sites;

§ Mean residue levels of neonicotinoids in pollen at site A were less than 1 ug/kg which, if comparable, indicates a dose rate of around 1/2th to 1/100th of the dose rate in laboratory experiments;

§ Residue levels of neonicotinoids in pollen and nectar collected by honey bees were of a similar magnitude at site B to the levels at site A. Residue levels were lower at site C (the site where growth was lowest);

§ Environmental temperature was generally lower at sites B and C than at site A;

§ The variety of pollen taken by bumble bees was similar between sites A and B, but was much greater at site C.

§ Monitoring of bee activity showed that there was no difference between sites A and B but there was comparatively reduced activity at site C early in the experiment, but not towards the end.

Interpretation of the results

§ The only significant difference in any of the end points between sites was the terminal mass of colonies at site C, the site with lowest neonicotinoid residues, as compared with colonies at the other two sites.

§ There are several possible reasons for this difference;

o Site C was treated differently from the other sites because that part of the project began two weeks later and the starting mass of colonies at this site were significantly lower than at the other sites;

§ This means they could have been exposed to different seasonal effects;

§ Because colony growth is exponential, the difference in starting mass could have a disproportionate influence on the final mass and this is difficult to address in a control;

o The temperature at Site C , especially at site A;

§ In animals like bees, which are cold-blooded, temperature can have a strong effect upon metabolic rate

§ This could be a significant factor in the lower growth in the colonies at this site

§ The period of reduced activity also was related to the periods of greatest temperature difference

o The pollen data suggest that the bumble bees at site C foraged on a wider spectrum of pollen compared with bumble bees at the other sites. This could reflect a preference for pollen not contaminated with neonicotinoids or the diversity of pollen sources in the three areas.

§ Consequently, it would not be safe to conclude that the mass of colonies at Site C is an effect of neonicotinoid exposure. Indeed, given all the other information, it seems unlikely that it is an effect of the pesticide and is more likely to be related to environmental differences at this site.

§ There is great variability in bumble bee colony performance and a paucity of scientific knowledge about the growth and queen production of normal bumble bee colonies. That said, the colonies in this study, including those at Site C, seem not to differ in their performance from the control and unexposed colonies in published academic work.

Conclusion

There is no statistically significant evidence of effects of these pesticides on bumble bees. .

13 March 2013

Prepared 28th March 2013