- 27 May 2013
This blog was created as part of the original Valuing Nature Network (2011-2014)
Pollinator decline is a complex challenge. There are many interacting threats, differing patterns of decline, and no obvious single solution. But here are FOUR actions for pollinators that we can all agree on.
The case of the disappearing bees is currently taxing some of the world’s best ecologists, insect physiologists, toxicologists and data analysts. It has deeply worried the public, the farming community and the beekeeping community. There are higher than usual colony losses in honey bees. Numbers of wild bee species in British landscapes have dropped substantially, leaving us with a degraded bee community that must be less resilient to change and stress than it used to be. We have, for example, around 40% fewer bumblebee species in any given 20 x 20 km square than we had in the 1950s and 60s (Carvalheiro et al. 2013).
Until recently, no-one was counting numbers of wild bees, so we can’t tell whether the widespread, common species are declining. We know that total numbers of butterflies and moths have been declining for decades, and even the common garden butterfly species are now decreasing in numbers (Fox et al. 2011).
So what’s to be done? At the moment, no single cause fully explains the observed declines (Vanbergen et al. 2013). There is disagreement, even among scientists, over the relative importance of some causes, particularly neonicotinoid insecticides. But here are four actions that conservationists, policy makers, farmers and scientific evidence all support.
1) Protect and enhance resources for pollinators, everywhere
All pollinators, not just bees but also many flies, butterflies, moths, wasps and beetles, rely on flowers. Our 257 bee species in the UK eat only nectar and pollen, as adults and as larvae, so they rely entirely on flowers for food. Yet the number of flowers in the wider countryside declined calamitously in the 20th century and remains generally low. We lost 97% of our flower-rich meadows between 1930 and 1984 (Fuller 1987).
Pollinators also need nesting and resting places – rough grassland, scrub, patches of earth or old walls for example. Some prefer special habitats like heath, chalk grassland or sandy cliffs.
In 2010, I compiled evidence on how to conserve bees (Dicks et al. 2010). We evaluated this evidence for certainty and asked conservation practitioners to rate 59 different actions for importance (Sutherland et al. 2011). If you rank these actions, putting those considered most important with the most supporting evidence at the top, the first four are: sow arable field margins with wild flowers, restore species-rich grassland, plant parks and gardens with appropriate flowers and plant dedicated floral resources on farmland.
One way to ensure these things happen is through the reformed Common Agricultural Policy. There are options under current agri-environment schemes to sow nectar and pollen flowers and restore or manage flower-rich grasslands. These need to be much more widely adopted and linked on a farm scale to nesting resources.
2) Value pollination as an input to the agricultural and rural economy
Pollination of crops is an economically important service, currently provided to most farmers for free. Through enhancing the yield of many high value crops, it’s worth between £430 and £510 million to the UK economy (UK NEA 2011, Breeze et al. 2012). Amazingly, pollination doesn’t seem to be considered as an important agricultural input.
If you don’t believe me, read the latest Red Tractor Farm Assurance Crop Specific Protocols. Assured protocols for some crops that we know rely on pollination, such as raspberry (over 40% yield loss without pollinators) and strawberry (10-40% yield loss without pollinators) neither explain the pollination requirements, nor offer any guidance on managing for pollinators.
Changing this mindset, so that pollination requirements are widely known and pollinator management is incorporated in standard crop management guidance, would be a very important step towards achieving number 1.
3) Monitor pollinators properly
At the moment, it is almost impossible for us to know whether actions to help bees and flies are having an effect, because we have no long-term monitoring of numbers of bees or flower-visiting flies. A large scale, systematic monitoring scheme for pollinators isn’t that expensive. Bumblebees are already being regularly counted by the Bumblebee Conservation Trust , through its BeeWalk survey. This will become increasingly valuable as data from each year are added, but needs ongoing financial security to keep it going for the long term.
A group of scientists recently estimated that you need 200 sampling locations, sampled twice every five years, to detect declines of 2-5% per year in the number of species or total abundance of all wild bees (LeBuhn et al. 2012). The cost, including all identification and storage of specimens, was estimated at $2 million. For the UK, that translates to £1.3 million over five years, or £260,000 per year. Just 0.06% of what crop pollination is worth.
4) Reduce pesticide use overall
There is little dispute that widespread use of pesticides creates a stress for pollinating insects, or that insects are often exposed to low levels of several different insecticides and fungicides. We have yet to be sure what the real size of this risk is. It certainly varies from place to place, from year to year and from insect species to insect species. But everyone would agree that we should keep the risk as low as possible, by avoiding unnecessary or excessive use of these chemicals. Farmers and agricultural researchers have been devising ways to do this for years, with methods known as ‘integrated pest management’, in which all options to reduce pest damage are applied together, and chemical treatments are the last resort, only used when absolutely necessary. This approach is not as widely adopted as it could be.
Total pesticide application rates in the UK rose by 6.5% between 2005 and 2010 (Breeze et al. 2012). So overall, things seem to be moving in the wrong direction, although we don’t have good publicly available data on pesticide use at local scales.
In 2011 and 2012, I compiled direct experimental evidence for effects of 116 different actions to protect wildlife on European farmland (Dicks et al. 2013). Again we evaluated the evidence for certainty and asked conservation-oriented farmers and advisers to rate the different actions. If you rank these actions and put those considered most important, with the most supporting evidence, at the top, ‘Reduce fertilizer, pesticide or herbicide use generally’ is in the top 10. Forty-seven different studies tested this action (summarised here). Taken collectively, experts agree they show a positive benefit to wildlife. So evidence-based policy would support this action to benefit all farm wildlife, not just pollinators.
These ideas will be presented at a Bee Summit in London on 28 June 2013, organised by Friends of the Earth, Waitrose, the Cooperative and the National Federation of Women’s Institutes. If you disagree with any of these actions, please get in touch and let me know why.
Lynn Dicks is a Research Fellow at the University of Cambridge, funded by the UK Natural Environment Research Council.
Follow @LynnDicks on Twitter
References
Breeze, T. D., S. P. M. Roberts, and S. G. Potts. 2012. The Decline of England's Bees: Policy Review and Recommendations. Friends of the Earth, London.
Carvalheiro, L. G., W. E. Kunin, P. Keil, J. Aguirre-Gutiérrez, W. N. Ellis, R. Fox, Q. Groom, S. Hennekens, W. Van Landuyt, D. Maes, F. Van de Meutter, D. Michez, P. Rasmont, B. Ode, S. G. Potts, M. Reemer, S. P. M. Roberts, J. Schaminée, M. F. WallisDeVries, and J. C. Biesmeijer. 2013. Species richness declines and biotic homogenisation have slowed down for NW-European pollinators and plants. Ecology Letters 16:870-878.
Dicks, L. V., D. A. Showler, and W. J. Sutherland. 2010. Bee Conservation: Evidence for the effects of interventions. 1 edition. Pelagic Publishing.
Dicks, L. V., I. Hodge, N. Randall, J. P. W. Scharlemann, G. M. Siriwardena, H. G. Smith, R. K. Smith, and W. J. Sutherland. 2013. A transparent process for ‘evidence-informed’ policy making. Conservation Letters. Early View online: http://onlinelibrary.wiley.com/doi/10.1111/conl.12046/abstract
Fuller, R. M. 1987. The Changing Extent and Conservation Interest of Lowland Grasslands in England and Wales - a Review of Grassland Surveys 1930-84. Biological Conservation 40:281-300.
Fox, R., T. Brereton, J. Asher, M. S. Botham, I. Middlebrook, D. B. Roy, and M. S. Warren. 2011. The State of the UK's Butterflies 2011.
Lebuhn, G., S. Droege, E. F. Connor, B. Gemmill-Herren, S. G. Potts, R. L. Minckley, T. Griswold, R. Jean, E. Kula, D. W. Roubik, J. Cane, K. W. Wright, G. Frankie, and F. Parker. 2012. Detecting Insect Pollinator Declines on Regional and Global Scales. Conservation Biology 27:113-120.
Sutherland, W. J., D. Goulson, S. G. Potts, and L. V. Dicks. 2011. Quantifying the impact and relevance of scientific research. PLoS ONE 6(11): e27537. doi:10.1371/ journal.pone.0027537.
UK National Ecosystem Assessment. 2011. The UK National Ecosystem Assessment. UNEP-WCMC, Cambridge.
Vanbergen, A. J. and The Insect Pollinators Initiative. 2013. Threats to an ecosystem service: pressures on pollinators. Frontiers in Ecology and the Environment 11:251-259.