Neonicotinoids: Are they killing our bees?



The UK government has announced that whilst it accepts the European Union ban on neonicotinoid pesticides, it 
does not believe that there is enough scientific evidence to support this action.

 In April, the EU banned the use of neonicotinoid pesticides for two years starting in December because of concerns over their effect on bees.  The use of these pesticides will not be allowed on flowering crops that attract bees or by the general public, however winter crops may still be treated. Fifteen countries voted for this ban, with eight voting against it (including the UK and Germany) and four countries abstaining.

Neonicotinoids were originally thought to have less of an impact on the environment and human health than other leading pesticides. They are systemic insecticides, which means they are transported throughout the plant in the vascular system making all tissues toxic to herbivorous insects looking for an easy meal. The most common application in the UK is to treat seeds before they are sown to ensure that even tiny seedlings are protected against pests.

Image by Kath Baldock

The major concern over neonicotinoids is whether nectar and pollen contains levels of pesticide is high enough to cause problems for bees. It has already been shown that they do not contain a lethal dose, however this is not the full story. Bees live in complex social colonies and work together to ensure that there is enough food for developing larvae and the queen. Since neonicotinoids were introduced in the early 1990s bee populations have been in decline and there is a growing feeling of unease that the two may be connected. Scientific research has provided evidence both for and against a possible link leaving governments, farmers, chemical companies environmentalists and beekeepers in an endless debate about whether or not a ban would save our bees.

Several studies on bees have shown that sublethal levels of neonicotinoids disrupt bee behaviour and memory. These chemicals target nicotinic acetylcholine receptors, one of the major ways that signals are sent through the insect central nervous system. Scientists at Newcastle University recently showed that bees exposed to neonicotinoids were less able to form long-term memories associating a smell with a reward, an important behaviour when foraging for pollen and nectar in the wild.

Researchers at the University of Stirling fed bumble bee colonies on pollen and sugar water laced with neonicotinoids for two weeks to simulate field-like exposure to flowering oil seed rape. When the colonies were placed into the field, those that had been fed the pesticides grew more slowly and produced 85% less queens compared with those fed on untreated pollen and nectar. The production of new queens is vital for bee survival because they start new colonies the next year. Studies in other bee species have found that only the largest colonies produce queens, so if neonicotinoids have even a small effect on colony size it may have a devastating effect on queen production.

 

So why does the government argue that there is not enough scientific evidence to support a ban on neonicotinoids?

 
Image by Kath Baldock

In 2012, the Food and Environment Research Agency set up a field trial using bumble bee colonies placed on sites growing either neonicotinoid-treated oil seed rape or untreated seeds. They found no significant difference between the amount of queens produced on each site, although the colonies near neonicotinoid-treated crops grew more slowly. The study also found that the levels of pesticide present in the crops was much lower than previously reported.

I personally think that both laboratory and field studies bring important information to the debate, however neither has the full answer. Whilst more realistic, the government’s field trial suffered from a lack of replication, variation in flowering times and various alternative food sources available to bees. Only 35% of pollen collected by the bees was from the oil seed rape plants, so where oil seed rape comprises the majority of flowering plants available to bees the effect on neonicotinoids may be more pronounced. The laboratory research can control more variables to establish a more clear picture, however the bees in these studies were often given only neonicotinoid-treated pollen and nectar to eat, which clearly is not the case in a rural landscape. Flies and beetles have been shown to avoid neonicotinoids, which could mean that bees would find alternative food sources where possible. This would have a major impact on crop pollination.

We desperately need well-designed field studies looking at the effect of neonicotinoids on bees and the environment in general. Despite an EU moratorium on growing neonicotinoid treated crops, an allowance should be made for scientists to set up controlled field trials to study the effect of these pesticides on bees during the two year ban. It could be our only chance to determine the danger these chemicals pose to vital pollinators and the wider environment.

 

This blog is written by Sarah Jose, Biological Sciences, University of Bristol

Sarah Jose

Sustainable landscapes for the future

On the 18th of July, the Cabot Institute at the University of Bristol hosted a one day conference for academics, landscape designers, industrial partners and policy makers to discuss how to create sustainable urban landscapes for the future. The event was organised to promote the exchange of ideas and to combine expertise from all stages of the process to determine how to create spaces that would maximise biodiversity and environmental benefits whilst remaining somewhere that people love to use.

City Academy Meadow, Bristol

A common theme throughout the conference was whether green spaces in cities can be designed to accommodate the needs of both local wildlife and people. Professor Nigel Dunnett from the University of Sheffield was one of the principle designers of the Olympic Park landscape, where he created a stunning biodiverse pictorial meadow with a long flowering season. His presentation highlighted the importance of creating a landscape that wildlife will benefit from, but critically that people will use and love. Professor Dunnett argued that we take more joy from seeing a beautiful expanse of flowers than a lawn monoculture and that “beauty in biodiversity is about people in ecology”.  Landscape architect Kym Jones echoed this, describing landscapes that people don’t want to use as “socially unsustainable”, no matter how many environmentally-friendly boxes they tick.

Professor Dunnett’s urban meadows are controversial because he often uses non-native plant species in his design to increase the flowering period. Professor Jane Memmott of the University of Bristol Urban Pollinators research group presented data collected at nature reserves, farms and urban green spaces around Bristol that suggest most pollinators don’t really mind whether native or non-indigenous plant species are used, as long as they produce a lot of flowers. She reported that whilst pollinators are more numerous in nature reserves than urban sites, the cities retain a high level of species diversity that it is important to protect in the future. This called into question the BREEAM system of measuring sustainability in new developments, which does not usually allow non-native species to be incorporated into a design.

Professor Graham Stone

The debate about whether people would accept more biodiverse landscapes continued by questioning public opinion. Many established parks are attached to historical expectations of that place; typically well-manicured lawns and pruned trees. The group agreed that it was time to try and change the public’s  perception to accept a little wilderness in parks and gardens as a habitat for local wildlife. Urban meadows begin to look neglected after flowering, however Professor Graham Stone of the University of Edinburgh mentioned that it is important to let the plants produce their seeds to provide birds with an important food source in the autumn. Bristol City Council have been trialling annual meadows in central reservations around the approaches to the city, and reported that they had not had any complaints from local residents about plants looking untidy when dying back at the end of the season. With sustainable landscaping becoming more popular in UK schools and communities, it is hoped that the public perception towards ecologically friendly designs have already begun to change.

Dr. Sarah Webster presented DEFRA’s hopes for sustainable urban developments. The 2010 Making Space for Nature report outlined new guidelines for reducing the huge pressures on wildlife, which state that new landscapes should enhance the UK’s ecological network by being bigger, better and more connected to existing habitats. DEFRA is currently trialling “biodiversity offsets”, where companies restore an equivalent area for every habitat that is unavoidably lost during a development. It is currently undecided whether or not these offsets will be mandatory if introduced, and it remains difficult to quantify the importance of a habitat in order to produce a new site of equal value to the environment. If this scheme goes ahead, careful planning could ensure that urban landscapes become more connected and form ecological networks within cities.

One of the major difficulties facing the landscape industry is how to measure the economic benefits of sustainability. Howard Wood presented his work with Lyon Parks Department in France, an ambitious project that saved hundreds of thousands of Euros over a year using ecologically-friendly design and maintenance. His team made their own compost from green plant waste and horse manure, killed weeds using hot water, used bio-control methods to remove pests, planted annual meadows to reduce mowing and maintenance of lawns, and used wood chippings as mulch to reduce weeds and improve soil water retention. The group decided that one of the key aims for the future is to improve the baseline knowledge of how much money different types of sustainable landscape cost to create or maintain, and whether they will cost councils and developers less in contrast to the traditional landscape designs.

The day ended with a request from the landscape industry partners for academics to make new sustainability research more easily accessible and understandable. Kym Jones mentioned that sustainability is now an integral part of landscape design, but landscape architects need to have the facts about its importance and value to be able to sell it to their clients. The overwhelming feeling was that green lawns alone are not enough; urban meadows promote biodiversity whilst producing beautiful displays of colour for people to enjoy. Professor Dunnett summed the day up best for me when he said, “we need to mix aesthetics and beauty with the science”. We are building places for people and local wildlife, and innovative new approaches

This blog is written by Sarah Jose, Biological Sciences, University of Bristol
Sarah Jose