Yesterday I went to the Federation of Middlesex Beekeepers’ Associations annual ‘Federation Day‘. Each year the Middlesex associations (Ealing, Enfield, Harrow, North London, Pinner & Ruislip) take it in turn to host a day of beekeeping talks; this year the day was organised by the Enfield association, in a remote area of north London which took me around 2 hrs 45 mins to reach from my part of west London!
The travelling was worth it as I learnt lots from three expert speakers. Below are my notes from the excellently-named first speaker, Professor Field. She works at Rothamsted agricultural research station, focusing on understanding insecticide mode of action and resistance at the biochemical/molecular level and then using this to develop better pest control strategies. Recently she has played a role in developing Rothamsted’s policy on the effect of neonicotinoids (neonics) on bees and a lot of her talk was spent giving us an update on the neonics situation.
Why do we use insecticides and what are the threats for bees?
Professor Linda M. Field. Head of Department, Rothamsted Research
Advantages of neonics:
- Very selective to insects, not toxic to mammals
- Systemic – travels through plant to leaves and flowers if used as a seed dressing (this has turned out to be less of an advantage than initially thought, as it means neonics end up in the nectar and pollen). Avoids the need for costly sprays which are potentially more damaging to local wildlife.
- Pests take a long time to develop resistance to neonics
- If used properly, little evidence that they directly kill bees
Problems with neonics
- The question is not “Are they killing bees?” but “Are they having a sub-lethal effect which causes problems for bees?” – for instance, stopping foraging bees finding their way home. There is evidence that this is the case, but we don’t understand why this might be.
- To gather research in the field, large-scale experiments are required to find out if neonics are a problem. These studies are not being funded by governments.
Lots of other factors beside pesticides are causing bees problems – varroa, viruses, weather, loss of forage – these are important but less easy to control and stop.
Where are we with neonics now?
In 2013, Regulation No 485/2013, the European Commission restricted the use of three neonicotinoid pesticides, clothianidin, thiamethoxam and imidacloprid, preventing the use of seeds treated with them in EU member states.
No-one has monitored the overall effect of the ban! The EU is not providing money for research into neonics. We have some scientific papers from independent organisations, but the research has been done in varying ways using different methods, making it hard to compare. A decision is unlikely to be made on what to do next until spring 2017.
The most recent EU report was in April 2015, by the European Academies Science Advisory Council (EASAC): Ecosystem services, agriculture and neonicotinoids. Professor Field recommended the conclusions at the end of the report (p.29) to us as the “easy bit to read”. She went through some of the report’s conclusions and gave us her comments on them:
“There is an increasing body of evidence that the widespread prophylactic use of neonicotinoids has severe negative effects on non-target organisms that provide ecosystem services including pollination and natural pest control.” (Conclusion 5)
Professor Field agreed with this but added that equally there are also papers which have found the opposite.
“Current practice of prophylactic usage of neonicotinoids is inconsistent with the basic principles of integrated pest management as expressed in the EU’s Sustainable Pesticides Directive.” (Conclusion 7)
Professor Field commented that people often take the word ‘prophylactic’ as implying unnecessary usage, whereas most farmers can reliably predict that certain pests will turn up each year. As mentioned above, one of the advantages of neonics is that pests take a long time to develop resistance to them. When the neonics ban was put in place here, weevils began destroying oil seed rape crops, resulting in some farmers spraying with pyrethroids 4-5 times in an attempt to kill them – but the weevils had developed resistance to pyrethroids. By the time farmers and agricultural advisers realised this, the sprays had also killed beneficial insects that might have helped control the weevils.
“Widespread use of neonicotinoids (as well as other pesticides) constrains the potential for restoring biodiversity in farmland under the EU’s Agri- environment Regulation.” (Conclusion 8)
Professor Field said there is a lot of debate going on about how to combine habitat diversity and farming. Should we try to share farming land with native species and make it biodiverse? A nice idea but not optimal for either farmers or wildlife. Or farm some areas of land intensively while leaving other areas aside for biodiversity? There is evidence that this approach may help rare species more.
Current UK situation
The UK government temporarily lifted the ban and allowed about 5% of farmers to sow neonic treated oil-seed rape in autumn 2015. This applied to farmers in areas where there is high resistance to pyrethroids in cabbage stem flea beetles, a pest of oil-seed rape. There are a lot of oil-seed rape crops out there which survived the initial onslaught but are full of beetle larvae waiting to attack. We may see farmers start to plant more field beans and pulses.
The COLOSS 2014-15 winter losses data showed low honey bee colony losses in the UK compared to many other European countries. The overall proportion of colonies lost (averaged out across all 31 countries surveyed) was 9%, the lowest since the COLOSS international working group started collecting data in 2007. But we really need the 2015-16 winter data to try and see if the ban has had an effect. There will be all sorts of factors affecting colony losses in any case, including the weather and varroa. We still have limited national data on numbers of solitary and bumble bees, which the EASAC report noted are more vulnerable to the risks from neonicotinoid use.
Insecticides and pollinators – are they incompatible?
Professor Field concluded that we can have both, through:
- Biological controls – for example plants that naturally repel insects or plants that are naturally resistant to pests. GM has the potential to engineer plants to be naturally resistant.
- Cultural controls – rotating crops more, mechanical sowing.
- Using pesticides as a last resort when other methods don’t work!
I was left feeling ambivalent about neonics. In some ways they are better than the pesticides that came before – none of us want to go back to DDT. At the same time, I would rather have a countryside which is more welcoming to pollinators. I support the EU ban because at least it’s trying something – at least it’s an attempt to protect pollinators, see what the effects of neonics are and if banning them can help.