Exposure to pesticides at levels bees encounter has subtle impacts, and can eventually make colonies fail
Jan 31, 2014 12:36 pm | Michele Colopy
“Scientists from Royal Holloway University have found that when bees are exposed to low levels of neonicotinoid pesticides – which do not directly kill bees – their behaviour changes and they stop working properly for their colonies. The results showed that exposure to pesticides at levels bees encounter in the field, has subtle impacts on individual bees, and can eventually make colonies fail.
This discovery provides an important breakthrough in identifying the reasons for the recent global decline of bees, a trend that has baffled many experts worldwide.
“One in three mouthfuls of our food depend on bee pollination,” said lead author, Dr John Bryden from the School of Biological Sciences at Royal Holloway. “By understanding the complex way in which colonies fail and die, we’ve made a crucial step in being able to link bee declines to pesticides and other factors, such as habitat loss and disease which can all contribute to colony failure.”
“Exposing bees to pesticides is a bit like adding more and more weight on someone’s shoulders. A person can keep walking normally under a bit of weight, but when it gets too much – they collapse. Similarly, bee colonies can keep growing when bees aren’t too stressed, but if stress levels get too high the colony will eventually fail,” added Dr Bryden.
“Our research provides important insights to the biology of pollinators,” said co-author Professor Vincent Jansen. “It is intriguing that the way in which bees work together is the key to their success, but could also contribute to their decline and colony failure.”
The research was funded as part of the £10 million ‘Insect Pollinators Initiative,’ set-up to understand the causes of pollinator declines and safeguard future pollination services.
“Pesticides can have a detrimental effect on bees at levels used in the field,” said co-author Dr Nigel Raine. “Our research will provide important evidence for policymakers. The way we test pesticides, the way we assess their impact on bees, and the way we manage pesticides can all be improved.””
Hannah Feltham • Kirsty Park • Dave Goulson
Accepted: 7 January 2014 Springer Science+Business Media New York 2014
“Bumblebees and other pollinators provide a vital ecosystem service for the agricultural sector. Recent studies however have suggested that exposure to systemic neonicotinoid insecticides in flowering crops has sub-lethal effects on the bumblebee workforce, and hence in reducing queen production. The mechanism behind reduced nest performance, however, remains unclear. Here we use Radio Frequency Identification (RFID) technology to test whether exposure to a low, field realistic dose (0.7 ppb in sugar water and 6 ppb in pollen) of the neonicotinoid imidacloprid, reduces worker foraging efficiency. Whilst the nectar foraging efficiency of bees treated with imidacloprid was not significantly different than that of control bees, treated bees brought back pollen less often than control bees (40 % of trips vs 63 % trips, respectively) and, where pollen was collected, treated bees brought back 31 % less pollen per hour than controls. This study demonstrates that field-realistic doses of these pesticides substantially impacts on foraging ability of bumblebee workers when collecting pollen, and we suggest that this provides a causal mechanism behind reduced queen production in imidacloprid exposed colonies.”
Sharing the Beekeepers Perspective
The Pollinator Stewardship Council Program Director met with Ohio State University Entomology students and professors, Wed., January 29, 2014 in Wooster, Ohio. A busy day of discussions with students and professors was filled with topics from the forest floor to pesticide applicators, corn planting to ornamental nurseries. Graduate students were immersed in their research, learning and seeking to understand the entomology in a nature preserve, honey bee hives, and re-purposing vacant city lots. Most importantly, the Pollinator Stewardship Council shared the experiences of beekeepers, and the real world interactions encountered by their honey bees. While science seeks clear, precise measurements and solutions, the interaction of honey bees in the environment is anything but clear and precise. Even in the environment of a contained greenhouse, the pollinators’ experience can be positively and negatively influenced by the human factor. Human factors include the worker who stands too long at one plant with the pesticide spray nozzle, or spills pesticide on the floor of the greenhouse and does not clean it up, or the worker who spills pesticide into the water source for the pollinators. While much emphasis of late has been directed at the use of insecticides, herbicides, and fungicides in agriculture, in some communities the greater exposure may be from homeowners, community gardens, and local nurseries. Beekeepers with hives in urban and suburban areas have experienced bee kills due to pesticide applications applied at nearby nurseries and garden centers. Depending on the floral sources available, honey bees will fly three to even seven miles in search of food. Reading the pesticide label, understanding how the pesticide interacts in the environment, and following the directions on the label are key to best management practices for pest control. Additionally, all persons using the pesticide must read and understand the label in order for it to be used safely.
The OSU entomology labs are busy working on a variety of projects that analyze the organisms that comprise the forest floor, to replanting vacant city lots, to assisting microbrewers in the growing of hops within urban areas. Sharing the experiences of beekeepers with these researchers is important for them to understand the real-world interactions of managed honey bees and of beekeepers. Again, while science seeks clear, precise measurements, the world of pollinators, the world of entomology is not precise, not when an organism interacts with the entire environment. The environment may be the forest floor, a vacant city lot, or a five mile flight radius, but a single organism does not inhabit the forest floor, a vacant city lot is hardly vacant of life, and a five mile flight radius provides a myriad of interaction possibilities. The Pollinator Stewardship Council wishes to thank Dr. Reed Johnson for inviting us to OSU. Many thanks to the staff at the Ohio Agricultural Research and Development Center in Wooster, Ohio including Dr. Luis Cañas, and Dr. Roger Downer, and the students of Dr. Dan Herms’ Lab, Dr. Mary M. Gardiner’s Lab, and Dr. Peter M. Piermarini’s Lab.
EPA Seeks Public Comment on Draft Guidance Documents for Evaluating Pesticide Spray Drift
Proposals Would Further Protect Communities near Fields Where Crops Are Grown
Comments must be received on or before March 31, 2014.
Docket identification (ID) number EPA-HQ-OPP-2013-0676
EPA is announcing the availability of two draft guidance documents for public comment. These documents describe how off-site spray drift will be evaluated for ecological and human health risk assessments for pesticides. Once final, these guidance documents will be posted on EPA’s Web site, to ensure consistent risk assessment practices and provide transparency for pesticide registrants and other interested stakeholders.
Pesticide drift can be characterized as the physical movement of a pesticide through the air at the time of application or soon thereafter from the target site to any non- or off-target site. This does not include pesticide movements by erosion, migration, volatility, or windblown soil particles after application. Drift is dependent on the design of application equipment, size of spray droplets or dry particles, weather conditions, and other factors.
Once off-target, pesticide drift can potentially deposit in unintended areas or directly onto people or nontarget species. To provide guidance to EPA staff and stakeholders, EPA has developed two documents describing EPA’s approach to assessing pesticide drift in human health and ecological risk assessments. Both documents are available in the docket for this action using the docket identifier EPA-HQ-OPP-2013-0676.
- Guidance on Modeling Offsite Deposition of Pesticides via Spray Drift for Ecological and Drinking Water Assessments for the Environmental Fate and Effects Division (Draft dated 11/1/2013) (Ref. 1), and
- Residential Exposure Assessment Standard Operating Procedures (SOPs), Addenda 1: Consideration of Spray Drift (Draft dated 11/1/2013) (Ref. 2).
The draft Ecological and Drinking Water Assessment Guidance provides information on estimating spray drift fractions of liquid sprays for modeling offsite deposition of a pesticide for ecological and drinking water assessment and on estimating distances from the treated field where adverse effects may be observed due to exposure to spray drift. The draft guidance also provides default assumptions for modeling inputs to use when estimating spray drift in terrestrial and aquatic assessments.
The Residential Exposure Addenda describes a screening approach for defining when assessments are needed and the methodology for estimating risks for indirect exposures to pesticide drift, such as children playing on a lawn that has pesticide residues that drifted from a nearby treated field. The draftguidance describes when quantitative risk assessments for spray drift are generally needed, and also provides the modeling inputs needed to complete the exposure and risk assessments.
EPA expects the model-generated values for spray drift fractions to provide realistic exposure and risk estimates for both ecological and human health assessments. These policies will promote consistency within EPA, as well as with other federal agencies and international regulatory partners that rely on predicted spray drift values.
Additional instructions on commenting or visiting the docket, along with more information about dockets generally, is available at http://www.epa.gov/dockets. Tips for preparing your comments. When submitting comments, remember to:
i. Identify the document by docket ID number and other identifying information (subject heading, Federal Register date and page number).
ii. Follow directions. The Agency may ask you to respond to specific questions or organize comments by referencing a Code of Federal Regulations (CFR) part or section number.
iii. Explain why you agree or disagree; suggest alternatives and substitute language for your requested changes.
iv. Describe any assumptions and provide any technical information and/or data that you used.
v. If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced.
vi. Provide specific examples to illustrate your concerns and suggest alternatives.
vii. Explain your views as clearly as possible, avoiding the use of profanity or personal threats.
viii. Make sure to submit your comments by the comment period deadline identified.
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