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June 2016

Seed-applied Neonicotinoids

Still in the spotlight

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  • Bee health affected by many different factors
  • Neonic-based seed treatments not harmful to pollinator populations if used properly
  • Bayer deeply committed to improving bee health
Neonicotinoids (or neonics as they are commonly known) are an important class of insecticides that help farmers worldwide to manage harmful pests that would otherwise limit crop production and quality. They are also of low toxicity to mammals and humans. But in recent years, the spotlight has been on neonicotinoids because of their allegedly harmful effects on pollinators. This article provides some insights into the present state of the debate.
In recent years, there have been substantial losses of honey bee colonies in certain regions over the winter months; this was particularly the case in Europe and North America. The phenomenon of increased bee mortality, e.g., Colony Collapse Disorder that first came to light in the U.S. in 2006, has also been the subject of scientific research and public concern. The debate that ensued in scientific circles and among the general public has focused on the possible causes. In view of the importance of pollinators for many crops, their role in securing global food supplies and humankind's centuries-old affinity for honey bees, the debate has often been conducted at an emotional level, especially by NGOs and environmental activists. Over the past decade, there has been a marked increase in the number of scientific publications and discussions exploring the potential effects of neonicotinoids on honey bees and other pollinators. Discussions within the scientific community have focused on the nature and extent of the potential lethal or sub-lethal effects of neonicotinoids as a result of the dust that may be released whilst sowing neonic-treated seed, and of residues from neonic seed treatments in the nectar and pollen of treated crops.
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35 % of all crops are pollinated by bees.

Are honey bees in decline?

Overall, the number of managed honey bee colonies has remained either relatively stable or increased across North America over the past decade or so. In Europe, colony numbers have been relatively stable. However, the total number of managed honey bee colonies worldwide rose by some 45 % between the 1960s and 2010. In other words, there is no statistical evidence of a general decline in honey bees worldwide. Even the oft-quoted overwintering losses present anything but a clear picture, as Dr. Christian Maus, Bayer's Global Pollinator Safety Manager, points out: “There is no correlation between bee colony losses and the use of neonics. The periodically occurring losses vary greatly in different countries, regions and years. In winter 2013/14, i.e., after the last season in which application of the full spectrum of neonics was allowed in Europe, the average colony loss in Europe was 9 %. In winter 2014/15, the first winter after implementation of the European Commission's restrictions on neonic usage, the loss rate was 17.4 %.”

EU restrictions on neonics

The restrictions Christian Maus is referring to were imposed by the European Commission in December 2013 in response to general concerns about the possible effects of neonics on pollinators and some emotional yet effective lobbying of EU bodies by NGOs and environmental activists. The decision to restrict the use of products containing three neonics – two from Bayer and one from Syngenta – on bee-attractive crops was taken in accordance with the precautionary principle in spite of non-conclusive scientific evidence. The restrictions were originally linked to a review of the registration conditions within a period of two years. Bayer's Dr. Susanne Buchholz, Global Public and Governmental Affairs department, explains the current situation: “Early this year, the European Food Safety Authority (EFSA) announced that its reevaluation of the three restricted neonics will not be completed until January 2017. When this reevaluation is published, we will see more clearly in which direction the debate is going.”

Negative impact of restrictions

Events since the imposition of EU restrictions in December 2013 show that they are not an effective way to save bees. In 2015, for example, oilseed rape – one of the most important sources of early-season forage for honey bees and other pollinators – was badly affected by the neonic-based seed treatment restrictions. In the UK 60,000 ha of oilseed rape were lost to pests and a further 38,000 ha were not planted due to the lack of effective crop protection alternatives. In Germany the oilseed rape acreage declined by 6 % while 10 % of crops were severely damaged by cabbage flea beetles. The oilseed rape story in Poland, the Czech Republic and Austria is basically no different. An additional outcome of the neonic restrictions has been an increase in foliar insecticide applications, farmers’ crop production costs and resistance issues.
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Bee care program improves bee health

The Bayer Bee Care Program is an industry-unique platform that is currently focusing on three areas to improve pollinator health – areas in which Bayer's expertise, know-how and experience can make a real difference in locally tailored solutions:

Feed a Bee: Advancing bee foraging, nutrition and pollinator biodiversity
Healthy Hives: Research-based solutions to tackle pests and pathogens, and to improve hive management
Sustainable Agriculture: Pollinator safety and responsible use of crop protection products, improved crop pollination, and better communications between beekeepers and farmers.

Multiple causes of bee mortality

Bee health is a complex issue affected by many different factors. In a study of managed honey bee populations in Europe and the U.S. published in 2009 two acclaimed bee scientists, Dennis van Engelsdorp and Marina Meixner came down firmly on the side of multi-causality in explaining bee mortality: “Varroa mites, together with the virus complex associated with mite parasitism, are likely (to be) one of the major causes for considerable overwintering losses documented by many northern nations over the last several years (…) Additional factors, such as reduced bee forage, climate, narrowing of the gene pool, poor queens, and socio-economic factors all have measurable effects on managed honey bee populations.” A most recent evaluation, the so-called IPBES report*, also essentially confirms the multifactorial nature of bee health issues. Although there is no consensus among bee scientists about the relative importance of the various stress factors impacting on bee health, the parasitic Varroa destructor mite and associated viruses are regarded as the major threat in countries in Europe and North America where the Western honey bee (Apis mellifera) is dominant. A survey published by Chauzat et al. in 2013 on the main causes of honey bee colony mortality as reported by EU beekeepers and bee health reference labs also pointed to diseases and the Varroa mite as the top two culprits.

* IPBES (2016): Summary for policymakers of the assessment report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services on pollinators, pollination and food production

Stewardship and safe usage

As numerous studies have proven, Bayer's registered neonic-based seed treatment products are not harmful to pollinator populations if used according to the label instructions. Dr. Christian Maus: “Irrespective of the debate on the potential impact on pollinators, we are continuing to work on the minimization of dust emissions from treated seed during sowing. In the past, isolated cases of lower-quality seed treatment or incorrect application led to dust emissions.” In recent years, Bayer has been investing heavily in product stewardship, advising seed treaters and farmers on the safest possible use of their products. “At Bayer we are dedicating a great deal of effort to optimizing treatment quality, sowing machinery and stewardship, and have made a lot of progress in minimizing dust emissions to environmentally safe levels.” In Bayer's ‘Zero Dust’ project experts are working to further reduce the generation and emission of seed treatment dust. Besides investigating how to formulate seed treatments and film coatings so they stick to the seed better, improvements are being made in seed treatment application, as well as in minimizing the spread of dust while sowing, e.g., through the Bayer Fluency Agent and Bayer SweepAir.

Clear seed treatment benefits

However heated the neonics debate may be, it is important to remember that neonics bring huge benefits since they are systemically distributed in the plant. When applied correctly as seed treatments, neonics protect the entire plant during its early growth stages. This dramatically reduces environmental exposure by applying the insecticide at the seed level, i.e., exactly at the place where it is needed and reducing the need for multiple foliar applications in later stages of the plant's life. An extremely reduced proportion of the area that needs to be exposed to the treatment, and its efficacy against otherwise hard-to-control soil pests and diseases are other key benefits that should not to be forgotten.
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Landscape-level study shows no effects on bee health

Dr. Christian Maus sums up the Mecklenburg-West Pomerania study: “Our aim was to provide a large-scale field-level study to investigate whether Clothianidin-treated seed affects the health of exposed bees. The study fields covered an area four times the size of New York's Central Park, and contained 95 bee hives with up to 30,000 worker bees per colony – a study of unprecedented magnitude and one of the most comprehensive evaluations ever of the impact of neonic-treated seed on pollinator health. In a lab we find out how an insecticide works and investigate its mode of action. But we still have an artificial exposure situation. In the outside world the interactions are much more complex. The results evaluated in 2015 revealed no difference between the exposed pollinators and the control group, no matter whether we looked at mortality, foraging activity or brood development parameters.”

The search for alternatives

For many years, Bayer has been investing heavily in insecticide research to develop alternative active substances in order to give farmers more choices. As a result, in the past few years, Bayer has launched two new foliar insecticides, SIVANTO™ and MOVENTO™, with the potential to replace certain neonic uses. With its unique formulation concept and excellent safety profile for honey and bumble bees, SIVANTO is a modern new tool for controlling major sucking pests. MOVENTO has a unique two-way systemic mode of action and provides the farmer with another effective option to control sucking pests. Both products with their state-of-the-art chemistry are excellent proof of Bayer's on-going efforts to develop new solutions with strong safety profiles to give growers a toolbox of solutions for controlling devastative pests through sustainable integrated pest management.

However, in spite of these successes in the search for new foliar solutions, there is still a lack of effective alternatives for on-seed application featuring new modes of action and delivering an agronomically acceptable level of control combined with an improved safety profile for users and the environment. After all, the required, well-balanced physicochemical properties for an active substance to be effective as a seed treatment are far more complex than the ones needed for a foliar pesticide. In consequence, neonics continue to play a key role for farmers in tackling a number of soil pests that cannot be controlled by any other alternative method.
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Long term, large scale, field level: The Mecklenburg-West Pomeranian study was designed to examine the determining factors for bee health.

Large-scale field studies

Bayer's response to the EU restrictions and EFSA's call for fresh scientific data in May 2015 has been to focus on collecting additional data from large-scale field studies in order to provide the authorities with data on potential impacts of neonic use on bee colonies under most realistic life conditions. A study conducted a few years ago in Ontario, Canada, investigated the impact on honey bee colonies of canola oilseed rape treated with the neonic Clothianidin. The five control and five test fields in the study were at least 2 ha in size and at least 10 km apart to exclude cross-contamination. The exposed hives were observed during the crop season and until after the subsequent overwintering. The results revealed no adverse effects on the colonies. In Mecklenburg-West Pomerania, Germany, Bayer commissioned a large-scale landscape monitoring study on bee pollinators in Clothianidin-treated winter oilseed rape. The monitoring was carried out and evaluated by acknowledged experts for honey bees, bumble bees (Bombus terrestris) and a solitary bee species (Osima rufa) with the involvement of an independent bee research institute and Cologne University. The study covered 17–18 oilseed rape fields totaling 600–800 ha in each 65 km2 control and treatment area. Here, too, no adverse short- or long-term effects of Clothianidin seed treatment were discovered.

On-going commitment

Regulatory authorities in the U.S. and Canada have maintained a balanced evaluation of the neonic situation, as Dr. Susanne Buchholz points out: “The Canadian Pest Management Regulatory Agency (PMRA) concludes in its value assessment of corn and soybean seed treatment that neonic seed treatments provide great economic benefits to growers. In conjunction with the PMRA value assessment, the U.S. Environmental Protection Agency (EPA) and the California Department of Pesticide Management Regulatory Agency (CDPR) have communicated their joint preliminary risk assessment for Imidacloprid, another neonic active substance from Bayer.

They conclude that there is minimal to no risk in most uses, including seed treatments in corn and soybean, and minimal to no risk from carryover residues in succeeding crops, soils and weeds. They point out that there might be a potential risk from foliar uses in cotton, citrus and some bee-attractive crops in Canada, which can be mitigated by current or pending label restrictions. We will continue to work with these regulators to discuss mitigation measures and to clarify areas of perceived potential risks. Besides North America, there are regulatory reviews going on in the EU, Asia and Latin America, specifically in Brazil.”

Bayer remains committed to delivering the best possible solutions to farmers, whilst taking into account all the relevant agronomical, environmental and societal risks and benefits. “For this reason,” says Dr. Christian Maus, “we have been establishing a worldwide network of scientists that includes independent scientists with no relationship to industry stakeholders, e.g., the University of Hohenheim in Germany, the Fraunhofer Chile Research Foundation or the Centre for Ecology and Hydrology in the UK. We favor such a broad-based perspective so we can base our bee health solutions on sound science. Many of our projects are linked to improving bee health and learning about pollinator ecology.” Since pollinators and agriculture are inherently linked, Bayer has been actively involved in finding solutions to improve bee health for nearly 30 years. This commitment will continue.
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