Public Release: 

The real reason to worry about bees

American Chemical Society

INDIANAPOLIS, Sept. 10, 2013 -- Honeybees should be on everyone's worry list, and not because of the risk of a nasty sting, an expert on the health of those beneficial insects said here today at the 246th National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society.

Set aside the fact that the honeybee's cousins -- hornets, wasps and yellow jackets -- actually account for most stings, said Richard Fell, Ph.D. Despite years of intensive research, scientists do not understand the cause, nor can they provide remedies, for what is killing honeybees.

"Some estimates put the value of honeybees in pollinating fruit, vegetable and other crops at almost $15 billion annually," Fell said. "Without bees to spread pollen from the male parts of plants to the female parts, fruit may not form. That would severely impact consumers, affecting the price of some of the healthiest and most desirable foods."

Farmers use honeybees to pollinate more than 100 different fruit and vegetable crops around the country in an approach known as "managed pollination." It involves placing bee hives in fields when crops are ready for pollination.

"The biggest impacts from decreased hive numbers will be felt by farmers producing crops with high pollination requirements, such as almonds. Consumers may see a lowered availability of certain fruits and vegetables and some higher costs," explained Fell.

He discussed the ongoing decline in honeybee populations in the U.S. and some other countries -- a condition sometimes termed colony collapse disorder (CCD). Although honeybees have been doing better in recent years, something continues to kill about 1 in every 3 honeybees each year. He spoke at a symposium on the topic. Abstracts of other presentations appear at the end of this press release.

"There is a good bit of misinformation in the popular press about CCD and colony decline, especially with regard to pesticides," Fell said. He is an emeritus professor of entomology at Virginia Tech, and an authority on colony decline in bees. "I think it is important to emphasize that we do not understand the causes of colony decline and CCD and that there are probably a number of factors involved. Also, the factors that trigger a decline may be different in different areas of the country and at different times of year."

Some of the leading theories about the cause of CCD include the use of certain pesticides, parasites, diseases and overall hive nutrition. Beekeeper and other organizations are pushing to stop the sale of certain neonicotinoids, insecticides that some regard as the main culprit of CCD. However, Fell said that would be premature. The U.S. Environmental Protection Agency recently reviewed the situation and concluded that there is no scientific evidence that the neonicotinoids are causing serious problems with bee colonies.

Honeybees are not the only species of bee that can be used in managed pollination. If colonies continue declining, Fell believes that there will be an increase in the use of other species, including the bumble bee and alfalfa leafcutter bee. There are, however, measured declines in these species' populations as well. In addition, they are not as easily managed for pollination as the honeybee.

"The major advantages of using honeybees are ease of movement, both in and out of orchards or fields, as well as the ability to manage colonies for higher populations. Honeybee colonies can be moved from one crop to another in a single season, something that cannot be done easily with bumble bees or solitary bee species such as the alfalfa leafcutter bee," explained Fell. "If we can gain a better understanding of the factors causing honeybee decline, we may be able to apply this knowledge to protecting other species."


A press conference on this topic will be held Wednesday, Sept. 11 at 10 a.m. in the ACS Press Center, Room 211, in the Indiana Convention Center. Reporters can attend in person or access live audio and video of the event and ask questions at

Fell cited funding from the Virginia Department of Agriculture and Consumer Services, the National Honey Board, the Virginia Agricultural Council and the U.S. Department of Agriculture National Institute of Food and Agriculture.

The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 163,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

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Honey bee colony health, bee decline, and pesticides

Richard Fell,, Entomology, Virginia Tech, Blacksburg, VA 24061, United States

Managed honey bee colony numbers have declined significantly in the US over the last 60 years with annual losses now averaging over 30%. The majority of colony losses occurs during the winter months and is thought to be due to a combination of multiple stressors affecting colony health. The introduction and rapid spread of parasitic mites (tracheal and Varroa mites) in the mid to late 1980s lead directly to increased winter losses, but the introduction of in-hive acaricides significantly reduced mite impacts. In late 2006, several commercial beekeepers reported unexpectedly high colony mortality that was associated with the sudden loss of the adult worker population. The condition was named colony collapse disorder (CCD) and was reported shortly thereafter as a major factor associated with colony decline across the country. No specific causes of CCD have been identified, but a number of possible causes have been suggested, including parasite loads, pathogens (viruses and Nosema), queen failure, nutritional stress, migratory stress, and pesticide contamination. Since 2007, investigations of colony losses and bee decline have focused on pesticides and pesticide residues in hives, particularly the neonicotinoids, imidacloprid and clothianidin. Pesticide contaminants and residues in comb have been shown to affect colony health through impacts on worker behavior, disease susceptibility, longevity, and queen and drone reproductive physiology. However, there is no evidence that specific insecticides like the neonicotinoids play a more significant role in colony decline.

Risk assessment framework for honey bees

Reuben Baris,, Kristina Garber. Office of Pesticide Programs, US Environmental Protection Agency, Washington, DC 20460, United States

The US Environmental Protection Agency in collaboration with Health Canada's Pest Management Regulatory Agency and the California Department of Pesticide Regulation developed a tiered risk assessment framework for bees, relying heavily upon the honey bee (Apis mellifera) as a surrogate. This process was recently presented to a FIFRA Scientific Advisory Panel comprised of technical experts from academia and government. The framework identifies specific protection goals and assessment endpoints for which risk would be evaluated. At a screening level, risk is quantified based on dietary and contact routes of exposure for individual larval and adult bees, while higher tier assessments qualitatively evaluate potential risks to the entire colony. This presentation will provide a broad overview of the risk assessment process for bees by describing measures of exposure and effect and risk estimation. Emphasis will be placed on characterizing exposure of bees to pesticides using modeling and monitoring data.

Intersect of pesticides and pollinators: Challenges faced by state regulatory programs

Liza J Fleeson,, Office of Pesticide Services, Virginia Department of Agriculture and Consumer Services, Richmond, VA 23219, United States

All pesticides must be either registered or exempted from registration by the US Environmental Protection Agency (EPA) before they can be sold or distributed in the US. As part of the registration process, EPA evaluates a pesticide to ensure that it will not have unreasonable adverse effects on humans, the environment, and non-target species. The legal use of a pesticide is dictated by the instructions on the label that is developed as part of the federal registration process for all pesticide products and serves as an agreement between the EPA and the end user of the product. While the EPA registers pesticides, it is state pesticide regulatory programs that have primacy and ensure that pesticide use is consistent with the product label. State pesticide programs ensure compliance through routine inspections, pesticide use observations, and investigations of possible pesticide misuse. In situations where the use of a pesticide is in a manner inconsistent with the label, a state regulatory program will take appropriate enforcement action. But what about those situations in which the use of the pesticide is legal and yet there are adverse effects to non-target species, for example, pollinators? In this session, we will explore regulatory issues faced by state pesticide programs when the legal use of pesticides and the protection of pollinators are seemingly at odds and the current efforts to provide for both.

Optimization of a method to quantify agrochemicals in bee tissues and wax

Michael J Lydy,, Da Chen, Zuyi Chen, Jesse Trushenski, Rebecca Kelley. Department of Zoology, Southern Illinois University, Carbondale, Illinois 62901, United States

An analytical method was developed to extract and to analyze simultaneously atrazine, chlorpyrifos, chlorothalonil, coumaphos, coralox, and τ-fluvalinate in bee tissues and wax. The optimized bee method used 3 g of bees and 30 mL of a 1:1 hexane:dichloromethane extraction solution. Cleanup was done using polystyrene-divinylbenzene cartridges capped with graphitized black carbon. The wax extraction method used 0.5 g wax and 10 mL of extraction solvent (same as for bees). Extracts were cleaned with a combination of Florisil solid phase extraction and gel permeation chromatography. Extracts were quantified using GC/MS-NCI for all of the target analytes, except atrazine, which was quantified using GC/MS-EI. Extraction efficiencies for the two matrices ranged from 70 to 120%, and minimum detection limits were well below reported toxicological benchmarks. In addition, total lipid extracts were conducted on the bees to separate the lipids into neutral and polar fractions and analyzed for fatty acid profile.

Analysis of pesticides in corn planter exhaust dust and dosimeters surrounding corn fields during planting

Brian Eitzer1,, Jeffrey D Holland2, Christian Krupke2. (1) Department of Analytical Chemistry, The Connecticut Agricultural Experiment Station, New Haven, CT 06511, United States, (2) Department of Entomology, Purdue Unviersity, Lafayette, Indiana 47907, United States

During planting of corn fields, the outer coating of treated seed can be abraded and absorbed to materials, such as talc, that are added to the planter to keep the seed flowing. This creates a dust that can contain very high concentrations of pesticides and that, when exhausted from pneumatic planting equipment (or air planters), have the potential to contaminate the areas around the fields. If pollinators visit these surrounding areas, they may be exposed to these pesticides, sometimes at lethal rates. We have been studying this phenomenon by analyzing the pesticides deposited on dosimeters placed around fields during planting at a distance of 0-100 meters. Although the amount of pesticides found on a dosimeter slide varied greatly, as much as 87 ug/m2 of an individual pesticide was observed during the 2012 tests. An additional set of fields will be monitored during the 2013 planting season, as well as planting with a newly developed seed lubricant. Methods of analysis and results for two years will be presented.

Is planting corn killing bees?

Kevin Neal,, Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States

In the spring of 2012 the Office of Indiana State Chemist (OISC) investigated several incidents wherein beekeepers believed they were suffering losses to bee hives during planting season for corn. Dead and dying bees were gathered. Analysis in the OISC residue lab significant levels of clothianidin were found in the bees, pollen, and also in and around the hives. Clothianidin is the active ingredient in a seed treatment process for corn and it appears that the dust from the planting corn was exposing bees to this insecticide. Results of the investigations by OISC investigators will be presented.

Pesticide residues in bee hives: What levels are of concern?

David L Fischer,, Environmental Safety Development - North America, Bayer CropScience, LP, Research Triangle Park, NC 27709, United States

Several recent published studies have performed chemical analysis of materials sampled from honey bee hives and suggested the frequency and levels of pesticides detected are high and likely cause for concern. However, these studies typically do not use risk analysis methods to confirm if in fact there is cause for concern. It would be helpful if a threshold Level of Concern (LOC) for concentrations in hive matrices were defined. Here I use published data and standard risk analyses approaches to define LOC values for commonly-detected pesticides in pollen, honey, and wax of honey bee hives. The LOC is defined as the threshold concentration that is likely to result in intake of a toxicologically significant dose for a worker honey bee. It is derived from endpoints measured in standard laboratory toxicity tests and conservative (near worst-case) assumptions for exposure levels. Ideally, a full data set consisting of acute and chronic test results with both adult and larval life stages of worker bees would be available. When data are lacking, conservative assumptions can be made to derive estimated toxicity values. Once LOCs have been defined, it becomes clear that pesticide residue levels reported in recent studies generally do not indicate there is cause for concern.

Using data from semi-field enclosure studies for assessing the risk of pesticides to honey bees

Joseph D Wisk,, Ecotoxicology Department, BASF Corporation, Research Triangle Park, North Carolina 27709, United States

North American pesticide regulatory agencies have recently developed a framework for assessing the risk of pesticides to honey bees. The framework includes the use of data from higher-tier, whole colony studies to address uncertainties from first-tier, screening level assessments. This presentation will focus on the use of semi-field enclosure studies to refine risk assessments. Semi-field studies allow for the assessment of exposure to and effects on the whole colony under more realistic exposure conditions, and they bridge the gap between laboratory and full field studies. Specific study design elements to assess exposure to and effects on different life stages and casts of honey bees will be discussed. Examples of data obtained from such studies will be presented. Advantages of these types of studies over other study designs will be highlighted. Limitations on the data that can be obtained and how it can be interpreted will also be discussed.

Honey bee field studies: Assessing hive health after four consecutive years of exposure to flowering crops grown from thiamethoxam-treated seed

Jay Overmeyer1,, P Campbell2, M Coulson2, N Ruddle2, I Tornier3. (1) Syngenta Crop Protection, LLC, Greensboro, NC 27419, United States, (2) Jealott's Hill Research Station, Syngenta Ltd., Bracknell, Berkshire, RG42 6EY, United Kingdom, (3) EcoChem GmbH, Eurofins Agroscience Services, Niefern-Öschelbronn, Germany

This study investigated the long-term potential risk to honey bee colonies under natural field conditions by assessing hive health over four years of consecutive exposure to corn and oilseed rape crops grown from thiamethoxam-treated seeds. To quantify exposure, pollen and nectar collected from honey bees after foraging on flowering corn (pollen only) and oilseed rape (pollen and nectar) were analyzed for residues of thiamethoxam and its primary metabolite CGA322704. Residues of thiamethoxam and CGA322704 in corn pollen collected from honey bees were low; ≤ 50% of the samples had quantifiable levels of thiamethoxam or CGA322704; maximum concentrations were 2 μg/kg for parent and the primary metabolite. For oilseed rape pollen and nectar, thiamethoxam was detected more frequently in nectar (83% of samples) compared to pollen (50% of samples), however maximum residues were also low, 1 μg/kg in pollen and 3 μg/kg in nectar. No quantifiable residues of CGA322704 were detected in oilseed rape pollen and nectar. Throughout the study, mortality, foraging behavior, colony strength, colony weight, brood development, and food storage levels were similar between treatment and control colonies. Detailed examination of brood development throughout the years demonstrated that colonies exposed to the treated crop overwintered successfully and had a comparable health status to the control colonies in the following spring. These data confirm low exposure with no resulting impact on honey bee health from potential residues in nectar and pollen following the use of thiamethoxam as a seed treatment on corn and oilseed rape.

Large-scale field study examining potential impacts on honey bees of exposure to clothianidin seed-treated canola

G Christopher Cutler1,, Cynthia D Scott-Dupree2, Maryam Sultan2, Andrew D McFarlane2, Larry Brewer3. (1) Environmental Sciences, Dalhousie University, Faculty of Agriculture, Truro, NS B2N5E3, Canada, (2) School of Environmental Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada, (3) Carolina Research Center, Smithers Viscient, Snow Camp, NC, United States

Numerous biotic and abiotic stressors have been suggested for the unusually high number of honey bee (Apis mellifera) colony losses experienced in many parts of North America and Europe the past decade. The neonicotinoid insecticides are widely used plant-systemic compounds. This class of insecticide contains the active ingredients imidacloprid and clothianidin and has perhaps been subject to more scrutiny and scorn than any other potential cause of honey bee colony declines. Many laboratory studies have shown that neonicotinoids may elicit various acute, chronic, lethal, or sublethal effects on honey bees. However, higher-tier studies where dietary exposure to pollen and nectar occurs from soil or seed treatment applications have failed to demonstrate significant colony level effects. Large-scale field studies are usually the most refined and realistic method of characterizing risks of agrochemicals to honey bees, but are rarely undertaken due to their complexity and high cost. In summer 2012, we initiated a large-scale field experiment in southern Ontario to determine whether or not exposure to clothianidin seed-treated canola has any adverse impacts on honey bees. Colonies were placed in the middle of clothianidin seed-treated or control canola fields during bloom, and thereafter they were moved to an apiary with no surrounding agricultural production. Colony weight gain, honey production, pest incidence, bee mortality, number of adults, and amount of brood were assessed in each colony throughout summer and autumn. Several of these endpoints and overall overwintering success will again be measured in spring 2013. Samples of honey, beeswax, pollen, and nectar were regularly collected and samples are being analyzed for clothianidin residues by GC/MS-MS.

Comparative ecotoxicology of bee-pesticide interactions

James E Cresswell,, Biosciences, University of Exeter, Exeter, United Kingdom

Neonicotinoid insecticides are widely used in crop protection. They are systemic and appear at trace levels in the nectar and pollen of mass-flowering crops which bees consume. Recently, the results of several semi-field trials have appeared in high-profile journals, and these have increased the public's concern over the use of neonicotinoids across extensive areas of crops and their potential threat to honey bees, wild bees, and valuable pollination services for crops and wild plants. Here, I summarise my laboratory investigations into the comparative resilience of individual adult bees to dietary neonicotinoids. I show that honey bees are likely to make a poor sentinel for effects on wild bees in general because they have a substantive capacity for metabolic detoxification. I also compare the effects of different neonicotinoids on individual bumble bees to show that impacts vary among these chemicals. Finally, I explore the potential for laboratory observations to underpin models of demographic toxicity, i.e., population projections based on effects on birth/death rates. I argue that these models are valuable tools for exploring the relative resilience or fragility of bee populations. I use this review to show that bee-neonicotinoid interactions are complex and likely varied in outcome and that care must therefore be taken to accommodate this into the evolving frameworks for pesticide regulation and environmental protection.

Honey bee colony level responses to exposure of residues on flowers of the fungicide, propiconazole

Francis A Drummond,, School of Biology and Ecology, University of Maine, Orono, Maine 04469, United States

Two field experiments (2011 and 2012) were conducted to assess honey bee colony level effects when foragers were exposed to flowers with residues of the fungicide, propiconazole, under typical pest management applications. In both years, isolated non-sprayed fields and isolated treated fields were selected to place 10-12 colonies in each field throughout bloom (period of 1 month). Every colony was monitored every 2-4 weeks both during and after bloom. Colony worker population, brood population, queen presence and health, queen egg laying rate, larval survival, worker longevity, hypopharyngeal gland size, and disease and parasitic mite prevalence were measured. Flowers and pollen were also collected for residue (exposure) measurement. We found that honeybee health affects of the commonly-used fungicide, propiconazole, are not entirely consistent between years. Although we can conclude that negative effects were documented. We found that overall exposure of honeybee foragers to residues on flowers does not reduce colony strength of worker or capped brood populations. Queen laying and capped brood survival also does not appear to be affected by exposure to sub-lethal doses of this fungicide. We did find evidence in both years to suggest that workers reared as larvae during bloom result in young nurse bees whose longevity is reduced.

Agrochemical formulant toxicities for honey bees

Christopher A Mullin,, Jing Chen, Wanyi Zhu, Maryann T Frazier, James L Frazier. Department of Entomology, The Pennsylvania State University, University Park, PA 16802, United States

Adjuvant and pesticide co-formulants are largely assumed to be biologically inert and are subject to minimal scrutiny and toxicological testing by regulatory agencies. Recently, we have shown that honey bees are unusually sensitive to organosilicone spray adjuvants and the solvent N-methyl-2-pyrrolidone, common co-formulants used in agrochemicals and spray adjuvants. Effects include learning impairment for adult bees and chronic toxicity in larval feeding bioassays. Most formulations we tested were more toxic to bees than their respective active ingredients. Knowing relevant environmental levels of adjuvants and inerts would allow improved risk assessment of total chemical loads and exposures for bee pollinators and other non-target species. We anticipate that if 'inerts' are influencing pesticide levels and general hive stress, formulation recommendations can be optimized for use in bee foraging areas. Impacts of synergistic pesticidal blends on bees cannot be fully understood without identification and risk assessment of co-formulant residues and their agrochemical interactions.

Pollinators, pesticides, and pathogens: Linking honey bee colony health to chemical exposures

Troy D Anderson,, Department of Entomology and Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia 24061, United States

The honey bee is the most widely managed crop pollinator and provides our agricultural industry with the sustainability and economic viability needed to satisfy the food and fiber needs of our society. The excessive use of pesticides is implicated in the reduced number of managed bee colonies available for crop pollination services. However, there are several gaps in our knowledge with respect to pesticide exposures and the health status of managed bee colonies. Thus, it is necessary to gather information relevant to the areas where knowledge is lacking to enhance our ability to predict conditions that are either favorable or unfavorable for bee colony health. Here, we will summarize our research findings related to pesticide impact on the microbiota community structure and function of managed bee colonies and the resulting nutritional and immune deficiencies that threaten colony health. These data are being used to model the health profiles for managed bee colonies exposed to pesticides in order to provide a theoretical framework to explain bee colony health thresholds and failures. In turn, the information gathered in this study will be translated into utilizable management practices to reduce the loss of managed bee colonies for both the apicultural and agricultural industry.

Addressing new data requirements for chronic honey bee testing in the EU

Steven L Levine1,, J Doering2, S Norman3, P Manson4, P Sutton5, H Thompson6. (1) Monsanto Company, St. Louis, MO 63167, United States, (2) Feinchemie Schwebda GmbH, Edmund-Rumpler-Str. 6, 51149 Cologne, Germany, (3) Dow AgroSciences, LLC, Indianapolis, IN, United States, (4) Cheminova A/S, Harrogate, HG3 1RY, United Kingdom, (5) Jealott's Hill International Research Centre, Syngenta, Harrogate, HG3 1RY, United Kingdom, (6) FERA, York YO41 1LZ, United Kingdom

To address new European Union (EU) data requirements for plant protection products, honey bee risk assessments are required where exposure of adults and larvae via direct contact or from residues in nectar and pollen cannot be excluded. Acute oral/contact toxicity studies are performed on adult bees and registrants may also be required to conduct Tier 1 larval chronic toxicity studies for which an OECD guidance is still under development or Tier 2 colony-level brood effects studies. For EU re-registration of glyphosate, potential exposure and effects on honey bee brood/colonies were assessed in separate studies. To quantify exposure, a greenhouse study involved a spray application of a glyphosate formulation to flowering Phacelia tanacetifolia during peak bee foraging. Glyphosate concentrations over time in forager-collected pollen and nectar were analysed. Mean glyphosate levels in nectar were >10X lower than in pollen and declined rapidly with DT50 values of 1-2 days. Pollen and nectar residue values were used as inputs to a bioenergetics-based exposure model to establish realistic worst case dose levels. To quantify effects on brood/colonies, a Tier 2 bee brood feeding study was performed using the Oomen test design. Colonies were tested at four dose levels including the control. Colonies were assessed 1 week prior and at weeks 1, 2, and 3 after dosing. Assessments tracked development of individual larvae and emergence, and the health of the colony as a whole with exposure confirmed by residue analysis of larvae collected from within the colony. No effects at any dose level were observed, consequently the No Observed Effect Level for brood development and adult survival was the highest dose tested, providing a sufficient margin of safety on the risk of glyphosate to honey bees. This conclusion is consistent with results of independently performed semi-field and field bee brood studies using a glyphosate-based formulation.

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