Fact Checks Farming In focus Insects

Are there more bees on organic farms?

26 October 2021
Olly

Claim

There are around 75% more wild bees on organic farms.

What the science says

Partially correct.

In farming landscapes different management methods such as use or avoidance of pesticides, boosting local habitat diversity, and creating flower strips can improve wild bee abundance, richness, and pollination ability1–3.

Many sources quote that the total abundance (or total number) of wild bees is 75% higher on organic farms than on conventionally managed farms. The research paper providing this information also reported that the species richness – which is a measure of the number of different species present – was also predicted to be nearly 50% higher on organic farms. However, these results are predicted values based upon data modelling and reality can be very different and vary from farm to farm.

This suggests that the use, or lack of use, of pesticides alone is a key determining factor of the presence of wild bees, but the results of the study were more complex than that. The research investigated the impact of many factors that could potentially have an impact, such as climate and local habitat surrounding the crop fields. The findings suggest that regional climate played a role in the abundance and diversity of wild bees, and that good quality habitat around the study sites helped to boost wild bee numbers.

Overall, this study predicted that local habitat diversity and organic farming both have distinct, positive impacts on wild bee abundance and richness, with organic farming methods alone showing the biggest boost to wild bee numbers.

Where the claim came from

Bumblebee on oilseed rape.

There are numerous news articles and websites providing the quote that:

There are around 75% more wild bees on organic farms

These sources include the Soil Association on their ‘Facts About Bees’ page4, several organic food organisations online5–7, and news outlets such as Farming UK8.

The statistic originally comes from a study carried out by Kennedy et al. (2013)9.

What the Science Says – the fuller picture

The claim that there are 75% more wild bees on organic farms, as opposed to conventional farms, comes from research published in 20139, which analysed data from 39 published studies across 605 field sites. This data was used in computer modelling to understand the different factors affecting wild bee numbers. The studies looked at 23 different crops grown across 14 countries in tropical, sub-tropical, Mediterranean, and temperate climates.

Ninety-one field sites were categorised as ‘organic’, meaning they do not use, or have reduced their use of pesticides and fertilisers. The remaining 514 field sites were categorised as ‘conventional’, meaning they primarily use synthetic materials such as pesticides and fertilisers to help crop growth. The studies that were included all looked at crop-growing farms, rather than livestock or mixed farms.

The study models predicted that the total abundance of wild bees could be up to 74% higher on field sites that were managed organically, and the average species richness of wild bees could be up to 50% higher on organic field sites. This finding was most pronounced on organic field sites in Mediterranean and temperate climates, which were estimated to have 68% and 42% higher wild bee abundance and 56% and 44% higher wild bee richness than in conventional fields in the same areas.

They also predicted that abundance and richness were higher if there was good quality, diverse habitat around the field sites, such as flower strips and field margins. These features could be present on both organic and conventional farms. Good local habitat alone was not as large a driver of wild bee abundance as organic farming methods, but the research found that with every 10% increase in high-quality bee habitats in a landscape, wild bee abundance and richness could increase by up 37%, on average.

It is important to note that this research only investigated wild bee abundance and diversity on crop farms, so the findings do not apply to all farms – but farms that only grow crops. The statement that “there are around 75% more wild bees on organic farms” is not strictly correct as it suggests that wild bee numbers were found through fieldwork, whereas this study used data to make predictions. That said, the data predictions do suggest that there is a strong link between wild bee numbers and organic farming methods. More research is needed to further assess the impact of organic livestock and mixed method farming on wild bees.

In addition to this study, there are lots of other pieces of research that have identified strong links between wild bee numbers and organic farming methods, because of the sympathetic land management and reduced use or lack of pesticides involved. Many studies have identified that local habitat diversity and availability of floral resources have a significant positive effect on wild bee abundance and diversity, as well as biodiversity in general. This effect is much more pronounced in smaller agricultural landscapes2,10.

When comparing conventional and organic farming, there are often common features such as flower strips and bee-friendly habitat, with the main difference between the two farming methods being the use or lack of use of pesticides and artificial fertilisers2. These commonalities can mean that organic farms that have bee-friendly habitat and avoid pesticide use can have a much bigger impact on wild bee numbers. Studies have found that organic farming methods increase wild bee species richness by 30%11 – 60%12, with abundance increasing by 60% for solitary bees and 150% for bumblebees on organic farms12. Other studies have cited that abundance of solitary bees declined by 33% under conventional management where pesticides were used10. Biodiversity in general is also thought to be 35% higher in organic fields than in conventional fields13.

Organic vs conventional farming – what is the difference for bees?

Honey bee

Pesticide use

Wild bees are considered to be the most important pollinators of crops14, with wild bees and hoverflies being responsible for the majority of pollination services in the UK15,16. Pollinators of all kinds, particularly flower-visiting insects, face a number of stresses from habitat loss, climate change, lack of floral resources, and the use of pesticides17. As a result there have been severe declines in many flower-visiting insects over recent decades18. As knowledge of the impact of pesticides has increased, research has been carried out to better understand the problem and how to manage its impacts, but lots of this research focuses on honeybees rather than wild bee species17.

Pesticides such as insecticides, fungicides, and herbicides can be administered via spray or solid application, and by seed treatment or granules19. As a result, on conventional farms, wild bees and other pollinators can then be exposed via pollen, plant fluids, and surrounding soils20. Pesticide exposure has been linked to immune issues, increased susceptibility to parasites, poor foraging and reproduction, and mortality in wild bees19. There is also some evidence that these synthetic chemicals can bioaccumulate in wild bees and butterflies17.

On organic farms this risk to pollinators is thought to be much lower because use of these synthetic materials is not permitted. This is because a farm must do the following to be certified as organic in the UK21:

  • Avoid using pesticides and artificial fertilisers;
  • Maintain soil fertility though appropriate crop rotations and use of fertility building leys;
  • Control pests, weeds, and diseases with only approved materials and techniques; and
  • Using only approved products and substances to process food.

Although organic farming consists of avoiding both pesticides and artificial fertilisers and so we cannot separate the effects of the two, it is likely to be the absence of the former that is beneficial for bees rather than the latter.

Other factors

Organic crop farming methods are widely believed to be better for invertebrates and important pollinating insects for other reasons as well, one of which could be the slower paced, more sustainable, and wildlife-friendly method that organic farming represents22. Research shows that organic crop farming methods promote soil health and structure23 and provide shelter and food for pollinators in toxin-free spaces22. The use of fertility-building grass and legume leys (areas of cover crops) provides this, improving soil health and structure, and attracting wild bees by providing extra flowers in the local landscape24,25.

These changes mean that organic crop farms can provide food, water, shelter, mating space, and nesting grounds for wild bees – in Europe this equates to 60-70% of wild bees19. As a result, organic farming can increase wild bee diversity and abundance on a local and landscape level12 and can support 30% more species than the same area of conventionally managed farm land11,26.

There are also additional management choices that can make organic crop farms more ‘bee-friendly’, with some debate surrounding whether these factors have a bigger impact on wild bee abundance than the lack of or use of pesticides. Studies by other researchers state that flower strips and other non-crop measures are significant attractors of pollinators13 and twice as good at boosting biodiversity than ‘on-field’ organic measures such as lack of pesticide use27.

However, there is lots of evidence that suggests that increasing the amount of organically grown crops can significantly boost pollinator abundance12, even when flower strips are at a minimum26. This could be a result of more flowering plants on organic farms generally, which are typically 32 times higher in organic crop fields12. Higher wild bee abundance is also likely to be a due to the lower rates of production observed on organic farms, which result in less disturbance to the habitats the bees use13.

Conclusion:

Various studies, including that by Kennedy et al. (2013) strongly suggest that wild bee abundance and diversity is higher on crop farms that are managed organically. There are lots of studies that suggest that other measures such as flower strips and field margins can also have a big impact on wild bee populations in agricultural landscapes, but a simple shift to organic crop farming can be advantageous for wild bees3.

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References

  1. Park, M.G., Blitzer, E.J., Gibbs, J., Losey, J.E. & Danforth, B.N. (2015). Negative effects of pesticides on wild bee communities can be buffered by landscape context. Proceedings of the Royal Society B: Biological Sciences, 282:
  2. Winfree, R., Williams, N.M., Gaines, H., Ascher, J.S. & Kremen, C. (2008). Wild bee pollinators provide the majority of crop visitation across land-use gradients in New Jersey and Pennsylvania, USA. Journal of Applied Ecology, 45:793–802.
  3. Geppert, C., Hass, A., Földesi, R., Donkó, B., Akter, A., Tscharntke, T. & Batáry, P. (2020). Agri-environment schemes enhance pollinator richness and abundance but bumblebee reproduction depends on field size. Journal of Applied Ecology, 57:1818–1828.
  4. Soil Association. Facts About Bees. Available at: https://www.soilassociation.org/take-action/growing-at-home/bee-organic/10-facts-about-bees/ (Accessed: 14 September 2021)
  5. Coombe Farm Organic. The Power of Bees. Available at: https://www.coombefarmorganic.co.uk/articles/2021/02/177-the-power-of-bees (Accessed: 15 September 2021)
  6. Helen Brownings. (2021). World Bee Day 2021. Available at: https://helenbrowningsorganic.co.uk/news/world-bee-day/ (Accessed: 15 September 2021)
  7. Go Organic. (2020). The climate crisis is the problem. Could organic farming be the answer? Available at: https://goorganicuk.com/blog/articles/the-climate-crisis-is-the-problem-could-organic-farming-be-the-answer (Accessed: 15 September 2021)
  8. FarmingUK Team. (2014). Organic farming can help save bees. Available at: https://www.farminguk.com/news/organic-farming-can-help-save-bees_29986.html (Accessed: 14 September 2021)
  9. Kennedy, C.M., Lonsdorf, E., Neel, M.C., Williams, N.M., Ricketts, T.H., Winfree, R., Bommarco, R., Brittain, C., Burley, A.L., Cariveau, D., Carvalheiro, L.G., Chacoff, N.P., Cunningham, S.A., Danforth, B.N., Dudenhöffer, J.H., Elle, E., Gaines, H.R., Garibaldi, L.A., Gratton, C., Holzschuh, A., Isaacs, R., Javorek, S.K., Jha, S., Klein, A.M., Krewenka, K., Mandelik, Y., Mayfield, M.M., Morandin, L., Neame, L.A., Otieno, M., Park, M., Potts, S.G., Rundlöf, M., Saez, A., Steffan-Dewenter, I., Taki, H., Viana, B.F., Westphal, C., Wilson, J.K., Greenleaf, S.S. & Kremen, C. (2013). A global quantitative synthesis of local and landscape effects on wild bee pollinators in agroecosystems. Ecology Letters, 16:584–599.
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  11. Tuck, S.L., Winqvist, C., Mota, F., Ahnström, J., Turnbull, L.A. & Bengtsson, J. (2014). Land-use intensity and the effects of organic farming on biodiversity: A hierarchical meta-analysis. Journal of Applied Ecology, 51:746–755.
  12. Holzschuh, A., Steffan-Dewenter, I. & Tscharntke, T. (2008). Agricultural landscapes with organic crops support higher pollinator diversity. Oikos, 117:354–361.
  13. Gabriel, D., Sait, S.M., Kunin, W.E. & Benton, T.G. (2013). Food production vs. biodiversity: Comparing organic and conventional agriculture. Journal of Applied Ecology, 50:355–364.
  14. Klein, A.M., Vaissière, B.E., Cane, J.H., Steffan-Dewenter, I., Cunningham, S.A., Kremen, C. & Tscharntke, T. (2007). Importance of pollinators in changing landscapes for world crops. Proceedings of the Royal Society B: Biological Sciences, 274:303–313.
  15. Breeze, T.D., Bailey, A.P., Balcombe, K.G. & Potts, S.G. (2011). Pollination services in the UK: How important are honeybees? Agriculture, Ecosystems & Environment, 142:137–143.
  16. Pfiffner, L. & Muller, A. (2016). Wild bees and pollination. Frick, Switzerland.
  17. Main, A.R., Hladik, M.L., Webb, E.B., Goyne, K.W. & Mengel, D. (2020). Beyond neonicotinoids – Wild pollinators are exposed to a range of pesticides while foraging in agroecosystems. Science of the Total Environment, 742:
  18. Goulson, D., Nicholls, E., Botías, C. & Rotheray, E.L. (2015). Bee declines driven by combined stress from parasites, pesticides, and lack of flowers. Science, 347:
  19. Uhl, P. & Brühl, C.A. (2019). The Impact of Pesticides on Flower-Visiting Insects: A Review with Regard to European Risk Assessment. Environmental Toxicology and Chemistry, 38:2355–2370.
  20. Bloom, E.H., Wood, T.J., Hung, K.L.J., Ternest, J.T., Ingwell, L.L., Goodell, K., Kaplan, I. & Szendrei, Z. (2021). Synergism between local-and landscape-level pesticides reduces wild bee floral visitation in pollinator-dependent crops The bee fauna of Lebanon View project Bees of Portugal View project. Article in Journal of Applied Ecology, 1–12. doi:10.1111/1365-2664.13871
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  23. ADAS. (2006). Soil and nutrient management on organic farms. Nottingham, England.
  24. Department for Environment Food and Rural Affairs. (2021). Create and maintain herbal leys. Available at: https://www.gov.uk/guidance/create-and-maintain-herbal-leys (Accessed: 12 October 2021)
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  27. Batáry, P., Dicks, L. V., Kleijn, D. & Sutherland, W.J. (2015). The role of agri-environment schemes in conservation and environmental management. Conservation Biology, 29:1006–1016.

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