Discovery of why two of the most economically important bee species are immune to one neonicotinoid insecticide but not to others promises to yield chemical treatments that protect crops from pests without harming these essential pollinators, honeybees and bumblebees.
Bee pollinators are equipped with biochemical defence systems, in the form of specific enzymes, that define their sensitivity to insecticides by enabling them to metabolise the chemicals safely, report an international team of researchers, led jointly by Rothamsted Research, the University of Exeter and Bayer AG.
"Some neonicotinoids are highly toxic to bees but others have very low acute toxicity; in public debate, they tend to get tarred with the same brush," says Lin Field, Head of Biointeractions and Crop Protection, who led the group at Rothamsted. "Each insecticide needs to be considered on its own risks and merits, not just its name."
The team's findings, published today in Current Biology, extend previous work by other researchers, who had linked immunity to rapid metabolism, by pinpointing the specific genes, and their enzymes, involved. The discovery opens up the opportunity to design bee-friendly insecticides.
"Identifying these key enzymes provides valuable tools to screen new pesticides early in their development to see if bees can break them down," says Chris Bass, Professor of Applied Entomology, who led the group at Exeter.
"It can take a decade and $260 million (£190M) to develop a single pesticide, so this knowledge can help us avoid wasting time and money on pesticides that will turn out to be harmful to bees," notes Bass. "The knowledge from our study can also be used to predict and prevent harmful effects that result from inadvertently blocking these key defence systems."
The EU introduced restrictions on the use of neonicotinoids in 2013 and, at the end of last month, the European Food Safety Authority published a review of research assessing the risks to bees that EFSA's Pesticides Unit began in 2015. An extension to the restrictions is now being considered.
"Identifying the mechanisms that contribute to inherent tolerance helps us, and regulators, to better understand why certain insecticides have a high margin of safety in bees," says Ralf Nauen, an insect toxicologist, who led the group at Bayer.
The three main neonicotinoids are imidacloprid, thiamethoxam and thiacloprid: the first two contain derivatives of nitroguanidine, an organic compound, and can be as toxic to bees as they are to the pests they target. The third contain derivatives of cyanoamidine, another organic compound, which honeybees can digest. Bumblebees show similar responses.
The research team pinpointed one subfamily of enzymes in bees, CYP9Q, which are part of the enzyme group known as cytochrome P450s that are also responsible for breaking down toxins in humans, as the key to the insect's immunity: CYP9Q3 in honeybees and CYPQ4 in bumblebees. "This knowledge," they report, "can be leveraged to safeguard bee health."
This research programme received funding from Bayer AG, a manufacturer of neonicotinoid insecticides. The work at Rothamsted comes under one of the institute's five strategic programmes (2017-2022), Smart Crop Protection, which is supported through the Industrial Strategy Challenge Fund of the Biotechnology and Biological Sciences Research Council. Rothamsted is also supported by the Lawes Agricultural Trust.
NOTES TO EDITORS
Manjon et al., 2018, Current Biology: Unravelling the molecular determinants of bee sensitivity to neonicotinoid insecticides [on publication, DOI will be 10.1016/j.cub.2018.02.045; for embargoed copies, contact email@example.com]
Rothamsted Research contacts:
Lin Field, Head of Dept of Biointeractions & Crop Protection
Susan Watts, Head of Communications
About Rothamsted Research
Rothamsted Research is the oldest agricultural research institute in the world. We work from gene to field with a proud history of ground-breaking discoveries. Our founders, in 1843, were the pioneers of modern agriculture, and we are known for our imaginative science and our collaborative influence on fresh thinking and farming practices. Through independent science and innovation, we make significant contributions to improving agri-food systems in the UK and internationally. In terms of its economic contribution, the cumulative impact of our work in the UK exceeds £3000 million a year (Rothamsted Research and the Value of Excellence, by Séan Rickard, 2015). Our strength lies in our systems approach, which combines science and strategic research, interdisciplinary teams and partnerships. Rothamsted is also home to three unique resources. These National Capabilities are open to researchers from all over the world: The Long-Term Experiments, Rothamsted Insect Survey and the North Wyke Farm Platform. We are strategically funded by the Biotechnology and Biological Sciences Research Council (BBSRC), with additional support from other national and international funding streams, and from industry. Our buildings and land, and some additional support, is provided by the Lawes Agricultural Trust.
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About Lawes Agricultural Trust
The Lawes Agricultural Trust (LAT), established in 1889 by Sir John Bennet Lawes, supports Rothamsted Research's national and international agricultural science through the provision of land, facilities and funding. The estates at Harpenden and Broom's Barn, including many of the buildings used by Rothamsted Research are owned by LAT through its corporate trustee LAT Company Ltd, which is also a charitable company. LAT provides an annual research grant to the Director, accommodation for nearly 200 people in differing housing facilities, and support for fellowships for young scientists from developing countries. The Trust also makes capital grants to help modernise facilities at Rothamsted, or invests in new buildings.
University of Exeter contacts:
Chris Bass, Professor of Applied Entomology
Alex Morrison, Press Office
About the University of Exeter
The University of Exeter is a Russell Group university that combines world-class research with very high levels of student satisfaction. Exeter has over 21,000 students and is in the top one per cent of universities worldwide. Exeter is also ranked 14th in The Times and The Sunday Times Good University Guide 2018 and 13th in the Guardian University Guide 2018. In the 2014 Research Excellence Framework (REF), the University ranked 16th nationally, with 98% of its research rated as being of international quality, while in 2017, Exeter was awarded a Gold rating in the Teaching Excellence Framework (TEF) assessment. Exeter was named The Times and The Sunday Times Sports University of the Year 2015-16, in recognition of excellence in performance, education and research. Exeter was The Sunday Times University of the Year 2012-13.
The University has four campuses. The Streatham and St Luke's campuses are in Exeter and there are two campuses in Cornwall, Penryn and Truro. In a pioneering arrangement in the UK, the Penryn Campus is jointly owned and managed with Falmouth University. At the campus, University of Exeter students can study programmes in the following areas: Animal Behaviour, Business, Conservation Biology and Ecology, English, Environmental Science, Evolutionary Biology, Geography, Geology, History, Human Sciences, Mathematical Sciences, Marine Biology, Mining and Minerals Engineering, Politics and International Relations, Renewable Energy and Zoology. The University launched its flagship Living Systems Institute in 2016, a world-class, interdisciplinary research community that will revolutionise the diagnosis and treatment of diseases. This follows recent investments of more than £350 million worth of new facilities across its campuses in recent years; including landmark new student services centres - the Forum in Exeter and The Exchange on the Penryn Campus in Cornwall, together with world-class new facilities for Biosciences, the Business School and the Environment and Sustainability Institute.
Ralf Nauen, Insect Toxicologist
Utz Klages, Head of External Communications
Bayer is a global enterprise with core competencies in the Life Science fields of health care and agriculture. Its products and services are designed to benefit people and improve their quality of life. At the same time, the Group aims to create value through innovation, growth and high earning power. Bayer is committed to the principles of sustainable development and to its social and ethical responsibilities as a corporate citizen. In fiscal 2017, the Group employed around 99,800 people and had sales of EUR 35.0 billion. Capital expenditures amounted to EUR 2.4 billion, R&D expenses to EUR 4.5 billion.
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