Bee Health: The Role of Pesticides
Bee Health: The Role of Pesticides
Linda-Jo Schierow
Specialist in Environmental Policy
Renée Johnson
Specialist in Agricultural Policy
M. Lynne Corn
Specialist in Natural Resources Policy
December 11, 2012
Congressional Research Service
7-5700
www.crs.gov
R42855
CRS Report for Congress
Pr
epared for Members and Committees of Congress
Bee Health: The Role of Pesticides
Summary
Bees, both commercially managed honey bees and wild bees, play an important role in global
food production. In the United States, the value of honey bees only as commercial pollinators in
U.S. food production is estimated at about $15 billion to $20 billion annually. The estimated
value of other types of insect pollinators, including wild bees, to U.S. food production is not
available. Given their importance to food production, many have expressed concern about
whether a “pollinator crisis” has been occurring in recent decades. In the United States,
commercial migratory beekeepers along the East Coast of the United States began reporting sharp
declines in 2006 in their honey bee colonies. The U.S. Department of Agriculture (USDA) reports
that overwinter colony losses from 2006 to 2011 averaged more than 32% annually. This issue
remained legislatively active in the 110th Congress and resulted in increased funding for pollinator
research, among other types of farm program support, as part of the 2008 farm bill (P.L. 110-246).
Congressional interest in the health of honey bees and other pollinators has continued in the 112th
Congress (e.g., H.R. 2381, H.R. 6083, and S. 3240) and may extend into the 113th Congress.
This report:
• Describes changes in managed and wild bee populations, given readily available
data and information. It focuses on managed and wild bees only, and excludes
other types of pollinators, including other insects, birds, and bats. Data on
managed honey bees are limited, and do not provide a comprehensive view of
changes in bee populations. Data for wild bee populations are even more limited.
• Provides a listing of the range of possible factors thought to be negatively
affecting managed and wild bee populations. In addition to pesticides, other
identified factors include bee pests and diseases, diet and nutrition, genetics,
habitat loss and other environmental stressors, and beekeeping management
issues, as well as the possibility that bees are being negatively affected by
cumulative, multiple exposures and/or the interactive effects of each of these
factors.
• Briefly summarizes readily available scientific research and analysis regarding
the potential role of pesticides among the factors affecting the health and well-
being of bees, as well as the statutory authority and related regulatory activities
of the U.S. Environmental Protection Agency (EPA) related to pesticide use.
A 2007 report by the National Research Council of the National Academy of Sciences, Status of
Pollinators in North America, provides a more detailed scientific context for this report and may
be consulted for more in depth understanding about bee health. That study concluded that many
factors contribute to pollinator declines in North America, and CRS accedes to that conclusion.
Accordingly, the focus of this report on bee exposure to pesticides is not intended to imply that
pesticides are any more important in influencing the health and wellness of bees than any of the
other identified factors influencing bee health. Pesticides are only one of the many influences on
bee health.
Because neonicotinoid pesticides have been the focus of concerns in Europe and in the United
States, this report briefly describes recent scientific research related to possible effects of
exposure to these pesticides on bees. The report concludes with a summary of recent regulatory
activity regarding neonicotinoids at EPA, the federal agency charged with assessing risks and
regulating U.S. sale and use of pesticides.
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Bee Health: The Role of Pesticides
Contents
Background ...................................................................................................................................... 2
Changes in Bee Populations ............................................................................................................ 4
Managed Honey Bees ................................................................................................................ 4
Native Bees ................................................................................................................................ 7
Timing of Bees and Associated Flowering Plants ............................................................... 8
Bumble Bees ....................................................................................................................... 9
Stingless Bees .................................................................................................................... 10
Interactions of Bees and Associated Flowers: Trophic Cascade ....................................... 10
Identified Factors Affecting Bee Health ........................................................................................ 10
Possible Role of Pesticides ............................................................................................................ 13
Pesticides and Pesticide Law ................................................................................................... 13
Statutory Framework ......................................................................................................... 13
Registration Process .......................................................................................................... 14
Exposure to Pesticides ....................................................................................................... 15
Impacts of Pesticides on Bee Health ....................................................................................... 15
Generic Pesticide Research ............................................................................................... 17
Research on Neonicotinoid Pesticides .............................................................................. 18
Neonicotinoid Registration Review at EPA ................................................................................... 22
Figures
Figure 1. Major Routes of Exposure of Foraging Bees to Pesticides ............................................ 16
Tables
Table 1. Honey-Producing Bee Colonies, 2002-2011 ...................................................................... 5
Contacts
Author Contact Information........................................................................................................... 23
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Bee Health: The Role of Pesticides
ees, both commercially managed honey bees and wild unmanaged bees, as well as
many other types of insect pollinators, play an important role in global food
B production. In the United States, the value of honey bees only as commercial
pollinators in U.S. food production is estimated at about $15 billion to $20 billion
annually. The estimated value of other types of insect pollinators to U.S. food
production is not available. Worldwide, the contribution of all insect pollinators—including
commercial bees and wild bees—to the worldwide crop production used directly for human food
is valued at €153 billion (or about $200 billion), according to the United Nations (UN).1
Given their importance to food production, many have expressed concern about whether a
“pollinator crisis” has been occurring in recent decades. Worldwide reports indicate that
populations of both managed honey bees and native bees have been declining, with colony losses
in some cases described as severe or unusual. In Europe, managed honey bee colony numbers
have been declining since the mid-1960s, and individual beekeepers have reported “unusual
weakening and mortality in colonies,” particularly during the period spanning winter through
spring.2 According to the United Nations, many insect pollinator species may be becoming rarer,
causing some to question whether this is further sign of an overall global biodiversity decline.
In the United States, commercial migratory beekeepers along the East Coast of the United States
began reporting sharp declines in their honey bee colonies starting in 2006. The U.S. Department
of Agriculture (USDA) reports that overwinter colony losses from 2006 to 2011 averaged more
than 32% annually. This issue was legislatively active in the 110th Congress and resulted in
increased funding for pollinator research, among other types of farm program support, as part of
the 2008 farm bill (P.L. 110-246).3 Congressional interest in the health of honey bees and other
pollinators has continued in the 112th (e.g., see H.R. 2381, H.R. 6083, and S. 3240) and may
extend into the 113th Congress.
Reasons cited for U.S. bee population decreases include a wide range of possible factors thought
to be negatively affecting pollinator species. For managed and wild bee populations, potential
identified causes for these declines include bee pests and diseases, diet and nutrition, genetics,
habitat loss and other environmental stressors, agricultural pesticides, and beekeeping
management issues, as well as the possibility that bees are being negatively affected by
cumulative, multiple exposures and/or the interactive effects of each of these factors. A 2007
report by the National Research Council of the National Academy of Sciences, Status of
Pollinators in North America4 (hereafter referred to as the “2007 NRC study”) describes many of
the factors affecting bee health and population effects.
Aside from the range of potential identified causes for bee colony declines, this report addresses
what role, if any, pesticides play in influencing the health and wellness of bees. It begins by
describing what is known about managed and wild bee populations, continues with brief
descriptions of factors that might be affecting those populations, including a more detailed look at
1 United Nations Environment Programme (UNEP), Global Honey Bee Colony Disorders and Other Threats to Insect
Pollinators, UNEP Emerging Issues, 2010, http://www.unep.org/dewa/Portals/67/pdf/
Global_Bee_Colony_Disorder_and_Threats_insect_pollinators.pdf.
2 Ibid.
3 For more information, see CRS Report RL33938, Honey Bee Colony Collapse Disorder.
4 National Academy of Sciences, National Research Council, 2007, Status of Pollinators in North America,
http://www.nap.edu/catalog.php?record_id=11761. Hereafter referred to as the 2007 NRC study.
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the potential effects of pesticide exposures, and concludes with a synopsis of pesticide risk
management at the U.S. Environmental Protection Agency (EPA).
Background
More than 200,000 species of insects (bees, butterflies, moths, flies, wasps, beetles, ants), bats,
birds and hummingbirds, and small mammals are plant pollinators. This report focuses on two
categories of bees only:
• Managed Honey Bees. Honey bees (Apis mellifera; Family: Apidae) are the most well-
known bee species. Honey bees are considered to be “social” bees in that they tend to work
together in a highly structured social order, consisting of cooperation and division of labor
within a colony, as well as the presence of two generations in a single nest at the same time.
This same social behavior also allows for bees to be domesticated and managed. However,
honey bees are only one of the world’s estimated 17,000 described bee species, and one of the
estimated total of 20,000 to 30,000 bee species worldwide.5 Honey bees are not native to
North America, but were introduced by European settlers in the 1600s.
• Wild Bee Species. An estimated 4,000 species of bees are native to North America.6 With few
exceptions, most of these are wild and not managed bees. Most types of wild bees are
“solitary” bees—estimated at about 3,500 species—and do not have long-lived colonies.7
Data and information on native bees are more limited than information on managed bees.
The five most common families of native bees in North America are Andrenidae, Apidae,
Colletidae, Halictidae, and Megachilidae. Andrenid bees are all ground nesters, and mostly
comprise a large family of dark, non-descript bees, although some are colorful. Bees in the
large Apidae family include not only honey bees, but also bumble bees (such as Bombus
spp.), carpenter bees, squash or gourd bees, and others. Bees in the smaller Colletidae family
are broader and wasp-like, and include plasterer bees. Bees in the Halictidae family include
many species of sweat bees, and most have shiny metallic colored or black bodies. Bees in
the Megachilidae family include resin and mason bees, orchard bees, and leaf-cutter bees that
mostly nest in holes. Most families of bees contain some types of parasitic and cuckoo8 bees.
For a summary see text box below.
Both managed and wild bee species are critical to plant pollination and are economically valuable
to U.S. agricultural production. In addition to honey bees, other types of bees are also managed,
such as bumble bees, orchard bees, and alfalfa leaf-cutting bees. Some of these bees exhibit some
of the social behaviors commonly associated with honey bees. These include bumble bees and
some types of stingless bees.
5 2007 NRC study, p. 36; and S. Fecht, “Hive and Seek: Domestic Honeybees Keep Disappearing, but Are Their Wild
Cousins in Trouble, Too?” Scientific American, May 8, 2012.
6 Iowa State University, “Native Bees of North America,” http://bugguide.net/node/view/475348.
7 2007 NRC study, p. 50; and Xerces Society, “Pollinator Conservation: Native Bee Biology,” http://www.xerces.org/
native-bees/.
8 Refers to bees that lay their eggs in another bee’s nest; as their eggs hatch early, the cuckoo larvae eat the other bee’s
provisions.
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Only data on managed honey bees are readily available. Data and information on native bees are
more limited. Where a few bee species are kept commercially and managed for their pollination
services, wild bee species also play an important role in providing pollinator services to both
commercial and small-scale home gardening systems.
Bee pollination of agricultural crops is said to contribute to the production of as many as 90
agricultural crops, including a wide range of high-value fruits, vegetables, tree nuts, forage crops,
some field crops, and other specialty crops.9 A number of agricultural crops are almost totally
(90%-100%) dependent on animal pollination, including apples, avocados, blueberries,
cranberries, cherries, kiwi fruit, macadamia nuts, asparagus, broccoli, carrots, cauliflower, celery,
cucumbers, onions, legume seeds, pumpkins, squash, and sunflowers.10 Other specialty crops also
rely on pollination, but to a lesser degree. USDA reports that native bees also provide pollination
services for a number of food crops. In addition to some of the aforementioned crops, these
include alfalfa seeds, almonds, canola, chokecherries, grapefruit, pears, plums, prunes, soybeans
(hybrid seed production), tomatoes, vegetable seeds, and watermelons.11
Classification of Bees
Kingdom
Animalia—Animal
Phylum
Arthropoda—Arthropods
Class
Insecta—insects, hexapoda
Order
Hymenoptera—ants, bees, wasps
Superfamily Apoidea—bees, sphecoid wasps, apoid wasps
Family
Andrenidae—andrenid bees, andrenids
Family
Apidae—honey bees, bumble bees, carpenter bees, squash bees, stingless bees
Family
Colletidae—colletid bees, plasterer bees, yellow-faced bees
Family
Halictidae—halictid bees, sweat bees
Family
Megachilidae—leafcutting bees, orchard bees, mason bees, resin bees
Family
Melittidae—melittid bees, melittids
Source: Integrated Taxonomic Information System (ITIS), ITIS is supported by a consortium of federal and
international agencies as well as scientific organizations to provide authoritative taxonomic information on known
plant and animal species. Available at http://www.itis.gov/. Condensed and slightly modified by CRS to include more
common names.
The economic value of pollination services provided by managed honey bees and wild bees is
difficult to quantify. One widely cited estimate of the monetary value of honey bees as
commercial pollinators in the United States is $14.6 billion annually.12 Most of the estimated
9 Staple crops (wheat, corn, and rice) do not rely on insect pollination and are mostly wind-pollinated.
10 R. A. Morse and N. W. Calderone, The Value of Honey Bees as Pollinators of U.S. Crops in 2000, March 2000,
Cornell University; and A.M. Klein, et. al., “Importance of pollinators in changing landscapes for world crops,”
Proceedings of the Royal Society B: Biological Sciences, Vol. 274, No. 1608, February 7, 2007.
11 USDA, “Agroforestry: Sustaining Native Bee Habitat Crop Pollination,” AF note-32, August 2006,
http://plants.usda.gov/pollinators/Agroforestry_Sustaining_Native_Bee_Habitat_for_Crop_Pollination.pdf.
12 R. A. Morse and N. W. Calderone, The Value of Honey Bees as Pollinators of U.S. Crops in 2000, March 2000,
Cornell University, http://www.masterbeekeeper.org/pdf/pollination.pdf. This estimated value is measured according to
(continued...)
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value is attributable to alfalfa (mostly for alfalfa hay), apples, almonds, citrus, cotton, and
soybeans. The 2007 NRC study reports other estimated values for honey bee pollination ranging
from $5.7 billion─$19.0 billion annually.
For native bees, estimates of the economic value of pollination services are not readily available.
However, a 2011 study by researchers at the University of California estimated that wild bee
species add $0.9 billion to $2.4 billion per year in value to California’s agriculture through
pollination services.13
Changes in Bee Populations
Managed Honey Bees
There are an estimated 115,000-125,000 beekeepers in the United States.14 Most of these (roughly
90,000-100,000) are hobbyists with fewer than 25 hives.15 Commercial beekeepers tend to have
more than 300 hives, and migrate their colonies during the year to provide pollination services to
farmers. In the United States, most pollination services are provided by commercial beekeepers.16
USDA does not compile comprehensive annual survey data on honey bee colonies. Available data
are limited and not ideal for evaluating population changes among honey bees. Annual data on the
number of honey bee colonies are from statistics tracking the number of operations that produce
honey for commercial sale. Additional data on all “colonies of bees” are from USDA’s five-year
Census of Agriculture (the most recent available data are for 2007 and 2002). These data are not
strictly comparable: Data are compiled for different purposes—the latter tracks all farms with bee
colonies, the former tracks operations that produce honey for commercial sale; also data are
compiled using different data collection techniques—one is a periodic census, the other a
statistical estimate. Generally, USDA data are mostly intended to track the number of honey-
producing colonies; however, it is the value of managed bees as crop pollinators that provides
perhaps the greatest economic impact in the production of food and feed crops.
Data from the most recent USDA Census of Agriculture indicate that 2.9 million bee colonies
were on U.S. farms in 2007.17 This compares to data from the previous Census in 2002 when
(...continued)
the additional value of production attributable to honey bees, in terms of the value of the increased yield and quality
achieved from honey bee pollination, including the indirect benefits of bee pollination required for seed production of
some crops.
13 R. Chaplin-Kramer, et al., “Value of Wildland Habitat for Supplying Pollination Services to Californian
Agriculture,” Rangelands, June 2011, Vol. 33(3): 33-41.
14 National Honey Bboard, “Beekeepers and Honeybee Colonies,” http://www.honey.com/nhb/media/press-kit/. Data
from 2012 industry survey, Bee Culture magazine.
15 A colony of bees is composed of between 250─50,000 individual bees (Source: D. Sammataro and A. Avitabile, The
Beekeepers Handbook, 4th Edition), although most larger, healthy, managed hives will have between 20,000─50,000
bees.
16 These operations are able to supply a large number of honey bee colonies during the critical phase of a crop’s bloom
cycle, when bees pollinate a crop as they fly from flower to flower collecting nectar and pollen, which they carry back
to the nest.
17 USDA, 2007 Census of Agriculture, Table 31, http://www.agcensus.usda.gov/Publications/2007/Full_Report/
Volume_1,_Chapter_1_US/st99_1_029_031.pdf.
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there were about 2.4 million bee colonies, reflecting an increase in the total number of bee
colonies. However, using similar data for the 1950s-1960s, there were an estimated 6 million
managed honey bee colonies.18 This may reflect ongoing consolidation and structural shifts in the
U.S. agricultural sectors, rather than conclusive trends in species populations, abundance, and
distribution.
USDA annual data for honey-producing colonies are similarly inconclusive. These data show
year-to-year fluctuations, but not a clear downward trend over time (Table 1). Over the 10-year
period shown, the number of bee colonies dropped from 2.6 million bee colonies in 2002 to 2.5
million bee colonies in 2011.19 However, the endpoints mask a 10-year high in 2010 when honey
production increased and the number of honey bee colonies reached nearly 2.7 million (Table 1).
This increase in the number of honey-producing hives may reflect efforts among beekeepers to
continually replenish their hives—either in response to a colony die-off or increase in the number
of hives to raise overall honey production or to provide additional pollinator services. This
increase might also reflect the rising popularity of beekeeping as a popular part-time hobby.
Table 1. Honey-Producing Bee Colonies, 2002-2011
Colonies
Honey Production
Year
(1,000 colonies)
(1,000 pounds)
2002
2,574 171,718
2003
2,599 181,727
2004
2,556 183,582
2005
2,413 174,818
2006
2,393 154,907
2007
2,443 148,341
2008
2,342 163,789
2009
2,498 146,416
2010
2,692 176,462
2011
2,491 148,357
Source: USDA, Honey, http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1191.
Honey producing colonies for producers with 5 or more colonies. Areas with the most honey bee colonies
include North and South Dakota; California; Florida; Montana, Minnesota, Idaho, and Texas. Other major states
are Michigan, Oregon, Georgia, Nebraska, New York, Washington, Wisconsin, and Wyoming.
Among all honey bee colonies, more than 2 million are reported to belong to commercial
migratory beekeepers and are rented each year to pollinate U.S. agricultural crops. An estimated
1.5 million colonies are needed each year to pollinate California’s 750,000 acres of almond trees
alone.20 Increasingly bee colony rentals are being used to pollinate cultivated blueberries in the
East Coast states and in the Midwest.21 Other information indicates that bee colonies are also
18 Presentation to Congressional staff by Jeff Pettis, USDA/Agricultural Research Service, June 18, 2012.
19 USDA, Honey, March 2012 http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1191.
20 C. Souza, “What’s the buzz about pollination?” California Country magazine, March/April 2011.
21 See, for example, “Honey Bees and Blueberry Pollination,” Fact Sheet 629, University of Maine Extension, April
2002.
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rented for apple, pear, plum, cherry, cranberry, avocado, cucumber, kiwi fruit, melon, pepper, and
citrus fruit production, as well as for alfalfa, clover seed, and sunflower production.22 Both locally
and globally, some are concerned that the availability of honey bee stocks is not keeping pace
with growing agricultural demands for pollination services.23
The 2007 NRC study voices concerns about the available USDA data on honey bees, cautioning
against use of these data to determine changes in honey bee populations. Concerns about these
data, including: the purpose of these data is to track U.S. honey production not bee populations;
lack of comparability among the available data compilations; the potential for misidentification of
species and miscounting because of data collection procedures; and other issues.24
Notwithstanding these concerns about data availability and quality, the 2007 NRC study
concluded: “Long-term population trends for the honey bee, the most important managed
pollinator, are demonstrably downward.”25 Honey bee colony losses are not uncommon. The 2007
NRC study cites USDA data showing honey bee declines in 1947–1972, and 1989–1996, as well
as declines starting in 2005 (despite reports of a sharp rise in 2010). These downward trends have
continued since that study was published, attributable to what is now known as Colony Collapse
Disorder (CCD), which is thought to have affected mostly managed bee colonies starting in late
2006.
As reported by USDA: “The defining characteristic of CCD is the disappearance of most, if not
all, of the adult honey bees in a colony, leaving behind honey and brood (immature bees confined
to cells in the hive, including larvae and pupae) but no dead bee bodies.”26 Scientists at USDA
and bee labs across the country have been looking for the cause or causes of CCD within four
broad categories:27
• Pathogens
(such
as
Nosema ceranae);
• Parasites
(such
as
Varroa mites);
• Environmental stressors (such as pesticides or lack of nectar diversity); and also
• Management stressors (such as transportation stress by migratory beekeepers).
22 Penn State University, “A Year in the Life of a Migratory Honey Bee Colony;” M. Burgett, 1999 Pacific Northwest
Honey Bee Pollination Survey, Oregon State University; and Brenda Kiessling, presentation at Green Spring Garden
Park’s “EcoSavvy Symposium,” Virginia, February 2012.
23 See, for example, M. A. Aizen and L. D. Harder, “The Global Stock of Domesticated Honey Bees is growing Slower
than Agricultural Demand for Pollination,” Current Biology, May 2009.
24 2007 NRC study, p. 3.
25 Ibid.
26 J. Kim Kaplan, “Colony Collapse Disorder: An Incomplete Puzzle,” Agricultural Research (USDA publication), July
2012, http://www.ars.usda.gov/is/AR/archive/jul12/colony0712.htm. For other information, see CRS Report RL33938,
Honey Bee Colony Collapse Disorder. The definition of CCD was recently revised to include other probably
contributing factors, such as low levels of Varroa mite and other pathogens, such as Nosema, which appear to be
associated with most winter colony losses. (Also see Benjamin Dinat, Jay D. Evans, Yan Ping Chen, et al., 2012,
“Predictive markers of honey bee colony collapse,” PLoS ONE , vol. 7, no. 2 (p. e32151).
27 J. Kim Kaplan, op. cit.
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As reported by USDA in July 2012: “While many possible causes for CCD have been proposed,
reported, and discussed—both in the scientific literature and popular media—no cause has been
proven.”28 These and other factors are discussed in “Identified Factors Affecting Bee Health”.
Heightened attention following concerns about CCD has resulted in better tracking by USDA of
annual honey bee colony losses. USDA reports that before 2006 bee colony losses averaged 15%-
20% per year since the 1990s, attributable to a variety of factors, such as mites, diseases, and
management stress. By comparison, bee colony losses between the winters of 2006/2007 and
2010/2011 averaged more than 32% during the year: Surveys found total colony losses of:29
• 30% in the winter of 2010/2011;
• 34% in the winter of 2009/2010;
• 29% in the winter of 2008/2009;
• 36% in the winter of 2007/2008;
• 32% in the winter of 2006/2007.
Other information from USDA indicates that colony losses range from 7% to 80% loss,
depending on area.30 Preliminary survey results indicate that total losses of managed honey bee
colonies from all causes were 22% nationwide for the 2011/2012 winter, representing a
substantial improvement in mortality compared to the previous five years.31
The leading causes of declining bee populations cited in the 2007 NRC study—which was
published before CCD became a well-publicized phenomenon—included pathogens and
introduced parasites, particularly Varroa destructor, the varroa mite. That study, among others,
documents the extensive, but still inconclusive literature on honey bee population losses due to
bee pests, parasites, pathogens, and disease, as well as other causes.
Native Bees
While managed bees are commercially important, wild bee species are important ecologically for
sustainable forests and fields. No comprehensive formal statistics are available on populations of
wild bees in the United States, despite numerous attempts to promote the use of various informal
“citizen science” initiatives in California, Florida, other East Coast states, and elsewhere.32 As
28 Ibid.
29 Dennis vanEngelsdorp, Jay Hayes, and Jeff Pettis, 2009, “Preliminary Results: A Survey of Honey Bee Colonies
Losses in the U.S. between September 2008 and April 2009.” Survey based on about 20% of all U.S. colonies.
30 Jeff Pettis, “Colony Collapse Disorder Affecting Honey Bee (Apis mellifera) Colonies,” October 2008 presentation,
http://www.epa.gov/pesticides/ppdc/2008/oct2008/session7-ccd.pdf. Survey based on 22 operations, managing 10% of
U.S. colonies, and AIA surveys.
31 D. vanEngelsdorp, J. Pettis, K. Rennich, et al., 2012, “Preliminary Results: Honey Bee Colony Losses in the U.S.,
Winter 2011-2012,” http://beeinformed.org/2012/05/winter2012/; K. Rennich, J. Pettis, D. vanEngelsdorp, et al., 2012,
“2011-2012 National Honey Bee Pests and Diseases Survey Report,” http://www.aphis.usda.gov/plant_health/
plant_pest_info/honey_bees/downloads/2011_National_Survey_Report.pdf; and USDA, “Survey by USDA and
Collaborators Reports Fewer Winter Honey Bee Losses,” May 31, 2012, http://www.ars.usda.gov/is/pr/2012/
120531.htm.
32 See, for example, the University of California’s backyard bee count (http://www.greatsunflower.org/), the University
of Florida’s “Native Buzz” project (http://www.ufnativebuzz.com/), and the “Bee Hunt” project organized by multiple
(continued...)
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already noted, an estimated 3,500 species are solitary bees, and these species are not readily
surveyed. Roughly an additional 500 species of bees native to North America show some degree
of social behavior. Scientific literature is replete with assertions about the paucity of data on one
group or another of native bees. Long term data are particularly difficult to obtain for wild bees.
As concluded by the researchers in the 2007 NRC study, among all wild pollinators:
There is evidence of decline in the abundance of some pollinators, but the strength of this
evidence varies among taxa. Long-term population trends for several wild bee species (notably
bumble bees) ... are notably downward. For most pollinator species, however, the paucity of long-
term population data and the incomplete knowledge of even basic taxonomy and ecology make
definitive assessment of status exceedingly difficult. 33
In the absence of comprehensive data, the following section describes selected information
gained about particular taxa or sites since the publication of the 2007 NRC study. As some of the
studies cited below demonstrate, scientists seeking to find any data to analyze broad pollinator
trends might be forced to rely on amalgamations of disparate studies, collections by citizen
scientists,34 and other unconventional approaches.
Timing of Bees and Associated Flowering Plants
A 2011 paper showed that the phenological changes in flowering times were accompanied by
changes in the spring emergence of bee populations.35 Reviewing a number of previous studies on
flowering times and pollination, the investigators found that ten species of bees (including both
solitary and social species) had advanced to earlier dates in the spring for their first emergence,
and the flowering times of the plants they visited also advanced. Advances in emergence time
over the period from 1970-2010 were highly significant. Various hypotheses to explain the
difference were examined; the data “[support] the idea that climate change is the main factor
explaining the observed phenological advances.” However, the authors “conclude that
phenological mismatch probably has not occurred already, but that it could occur in the future, as
rates of temperature warming increase.” At the same time, the study noted that it analyzed
generalist bees and generalist flowers—bees that visit many plant species, and plants visited by
many bee species.36 Where the life cycles of particular bee species are tied to particular plant
species, different trends may occur. While no data were reported on the population sizes of these
bees, in this study there was no clear connection between climate change (as measured by
(...continued)
university staff, federal agencies, and private partnerships (http://www.discoverlife.org/bee/index.html).
33 2007 NRC study, p. 7. See also 2007 NRC study, p. 88 (referring to Bombus, or bumble bees) ; p. 29 (referring to
pollinators generally in North America); and p. 203 (referring to the absence of baseline data on pollinator status
generally as an impediment to estimation of any decline).
34 A well-known example of citizen-scientist-based data in North America is the annual Christmas bird count, which
has been conducted for nearly a century in some areas. Data may not serve for some quantitative analyses, but may be
much more reliable for the presence or absence of a bird, for example. In other studies, on arrival dates at bird feeders,
or bees on spring flowers, the date on which a species is first observed could be another relatively reliable observation.
35 I. Bartomeus, J.S. Ascher, D. Wagner, et al., 2011, “Climate-associated phenological advances in bee pollinators and
bee-pollinated plants,” Proceedings of the National Academy of Sciences, v. 108, n. 51, pp. 20645-20649. Phenology is
the scientific study of biological phenomena that are cyclical or periodic. Examples include migration, hibernation, and
nesting, as well as flowering times. Phenology is particularly important in analysis of climate change.
36 The species studied were in four genera: Andrena (three species), Bombus (two species), Colletes (one species), and
Osmia (four species).
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flowering times) and any harm to the species studied. The bees seemed to be keeping up with the
changes in dates of flower availability.
In 2010, an international group of scientists reviewed global trends in pollinator species,
including bees.37 They cited a study based on data gathered by citizen-scientists in the United
Kingdom and in the Netherlands (number of years of observation varying by location) showing
that “in both countries, bee diversity has fallen significantly in most landscapes.... Analysis of
pollinator traits demonstrated that in bees ..., specialist (diet and/or habitat) and sedentary species
tended to decline, whereas mobile generalists tended to thrive.” As the authors also noted:38
The parallel dynamics between plants and their pollinators suggest a link between the two,
although this is correlative and the mechanism is as yet unknown. It could be that plant declines
are caused, in part, by a lack of pollination services, or bees could be declining owing to a lack of
floral resources, or indeed both could be declining owing to shared sensitivity to environmental
changes.
Bumble Bees
Compared to most native species, bumble bees (Bombus) are better studied. According to the
2007 NRC report, there are 239 species of bumble bees worldwide; of these, 60 species are found
in the U.S., Mexico, and Canada.39 Some species are managed in controlled environments to
pollinate greenhouse tomatoes. Others are valued as primary or supplementary pollinators for
members of the squash family such as cucumbers, watermelons, and cantaloupes.
In the United States, citizens are recruited to gather data on these large insects—for example,
forming Bumble Bee Brigades in one campaign.40 Even so, information about the wild bumble
bees is not comprehensive. One species (B. franklini) is thought to be extinct in its very limited
(former) range in northeastern California and southeastern Oregon. Hoping to establish trends for
some species, some scientists examined both museum collection records and intensive nationwide
surveys for records of abundance and distribution of eight species of this genus.41 Four species
have declined in relative abundance by up to 96%. These four also contracted their ranges by
23% to 87%. These changes were statistically highly significant; the other four species showed no
clear pattern in terms of range reduction. The authors hypothesized that the four declining species
may be affected by a pathogen (Nosemi bombi) as well as reduced genetic diversity.42 The data
were adequate only to show an association, rather than a cause—were the four species declining
because of the disease and low genetic diversity? Or was some other factor causing these species
37 S.G. Potts, J.C. Biesmeijer, C. Kremen, et al., 2010, “Global pollinator declines: trends, impacts and drivers,”
Trends in Ecology and Evolution, v. 25, n. 6, pp. 345-353.
38 Ibid.
39 2007 NRC report, p. 43.
40 The University of Wyoming, through its Berry Center, sponsors the program. See http://www.uwyo.edu/berrycenter/
citizen-science/bumblebees.html for more information.
41 S.A. Cameron, J.D. Lozier, and J.P. Strange, et al., 2011, “Patterns of widespread decline in North American bumble
bees,” Proceedings of the National Academy of Sciences, v. 108, n. 2, pp. 662-667.
42 The authors also noted that some believe that Nosema bombi was introduced via commercially imported European
bumble bees, and North American bumble bees may therefore have less resistance to the disease than European
species. They compare the impacts of the pathogen to the fungal infections currently devastating wild populations of
amphibians and bats.
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to decline and making them more susceptible to the disease and also reducing their genetic
diversity?
Stingless Bees
Meliponine bees, with about 400 species, belong to the same family (Apidae) as bumble bees and
honey bees.43 Commonly called stingless bees, they are found in the tropics, and were widely
cultivated by Native Americans in Central and South America before the introduction of honey
bees from Europe. While they do not sting, most species can inflict a serious bite. A few species
can produce a secretion from their mouth parts; added to a bite, the secretion may produce
blisters. Loss of forest cover eliminates nesting sites. The shift by beekeepers to honey bees for
more intensive production has also reduced the number of stingless bees. An analysis of the
effects of forestry on stingless bees in Brazil observed that most bee nests were found in hollow
trees over 50 cm (~20 inches) in diameter.44 Given the high value of the bees as pollinators for
many species of plants, and the low commercial value of hollow trees, the authors recommended
that managed forests maintain hollow trees as both seed sources and as homes for these bees.45 In
addition, some studies suggest that stingless bees are especially susceptible to some pesticides.46
Interactions of Bees and Associated Flowers: Trophic Cascade
The phenomenon known as trophic cascade may also play a role in the interaction of pollinator
species. Many plants can be pollinated by more than one species, and many bee species use more
than one pollen or nectar source. As individual pollinator species (bees or other species) decline,
other species may take over the declining species’ role. Where the data are available (as with the
Bombus study cited above), evidence suggests that, where a generalist bee species is able to step
in to provide pollination services (even if less able than a specialist bee), the effects of a reduced
bee population may be masked by the generalist. In more concrete terms, the presence of a highly
efficient generalist—like the honey bee—may mask the loss of native species (regardless of the
reason for the decline of the native species). If honey bees themselves then decline, the effects of
the lost population may be more severe because populations of back-up pollinators have already
been reduced or eliminated. And conversely, reductions in honey bee populations may reduce
competition sufficiently to allow other (reduced) bee populations to rebound to greater numbers.
Identified Factors Affecting Bee Health
Factors that have been identified to be negatively affecting managed and native bee populations
are (listed in no particular order):47
43 2007 NRC report, p. 48.
44 G. C. Venturieri, 2009, “The impact of forest exploitation on Amazonian stingless bees (Apidae Meliponini),”
Genetics and Molecular Research, v. 8, n. 2, pp. 684-689.
45 Ibid.
46 H.V.V. Tomé, G.F. Martins, et al., 2012, “Imidacloprid-induced impairment of mushroom bodies and behavior of the
native stingless bee Melipona quadrifasciata anthidioides,” PLoS ONE, v. 7, n. 6, p. e38406, http://www.plosone.org/
article/info%3Adoi%2F10.1371%2Fjournal.pone.0038406.
47 Compiled by CRS from multiple sources (2007 NRC study; USDA, Colony Collapse Disorder Progress Report,
CCD Steering Committee, June 2011; comments by Laurie Adams, North American Pollinator Protection Campaign
(continued...)
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• parasites, pathogens, and diseases (for a detailed listing, see text box);
• bee genetics including lack of genetic diversity and lineage of bees, and
increased susceptibility and lowered disease resistance, and also miticide
resistance by the mites;48
• diet and nutrition including poor nutrition due to apiary overcrowding,
pollination of crops with low nutritional value, and pollen or nectar scarcity
associated with invasive plants;
• bee management issues including transportation stress from migratory
beekeeping, overcrowding, feeding practices, chemicals used by beekeepers to
control mites (antibiotics and miticides), confinement and temperature
fluctuations, susceptibility to disease, potential for cumulative exposure to
diseases and parasites, use of bees for honey production versus pollination,
chemical residue or contamination in the wax, and reliability of the queen source;
• habitat loss, and other environmental or biological stressors including loss of
foraging area, interspecific competition between native and non-native bees,
pathogen spillover effects, and climate change;
• pesticides including acute or cumulative exposure to new types and
combinations of agricultural pesticides through a variety of media including dust,
water droplets, pollen, and nectar;
• other agricultural practices including the use of genetically incorporated
pesticides in seeds or treated seeds, such as with bioengineered crops; and
• potential cumulative and interactive effects of each of these factors.
These same factors were among those initially thought to be contributing to CCD. As outlined in
USDA’s 2011 progress report, the available research over the past few years on the numerous
possible causes for CCD has led USDA and university researchers to conclude that “no single
factor or specific combination of factors has been identified as a ‘cause’ [for CCD].”49 This has
led researchers to further examine the hypothesis that CCD may be “a syndrome caused by many
different factors, working in combination or synergistically;”50 it may also involve “an interaction
between pathogens and other stress factors.”51 USDA reports that researchers are continuing to
focus in three major areas: (1) pesticides that may be having unexpected negative effects on
honey bees; (2) a parasite or pathogen that may be attacking honey bees, including the pathogenic
gut fungus, Nosema, as well as viral infections; and (3) a combination of existing stresses that
may compromise the immune system of bees and disrupt their social system, making colonies
more susceptible to disease and collapse.52
(...continued)
(NAPPC) in a presentation to Congressional staff on June 18, 2012.
48 A miticide is a pesticide intended to kill mites.
49 USDA, CCD Progress Report, June 2011, http://www.ars.usda.gov/is/br/ccd/ccdprogressreport2011.pdf.
50 USDA, CCD Progress Report, June 2009, http://www.ars.usda.gov/is/br/ccd/ccdprogressreport.pdf.
51 D. vanEngelsdorp, J.D. Evans, C. Saegerman, et al., 2009, “Colony collapse disorder: A descriptive study,” PLOS
One, v. 4, n. 8, (August), e6481. doi:10.1371/journal.pone.0006481, http://www.plosone.org/article/info:doi/10.1371/
journal.pone.0006481.
52 USDA, “Q&A: Colony Collapse Disorder,” http://www.ars.usda.gov/News/docs.htm?docid=15572.
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Pests and Diseases Affecting Honey Bees
As noted in the 2007 NRC study, among the leading causes of managed honey bee losses are diseases, parasites, and
recently introduced competitors. Most notable are declines due to two parasitic mites, the so-called vampire mite
(Varroa destructor) and the tracheal mite (Acarapis woodi). Also of concern is the emergence of new or newly virulent
fungal and viral diseases. New invasive pests are also harming bees.
Below is a brief listing of some identified pests and diseases. For more information, see the 2007 NRC report and
other beekeeper guidance documents. The fol owing is mainly excerpted from The Beekeepers Handbook.
Honey bee diseases may be caused by a protozoan (e.g., bacteria or amoeba), fungus, or virus.
•
Nosema disease is the most common adult bee disease, and is caused by a microscopic fungus
(formerly considered to be a protozoan). Two Nosema species are found in honey bees: (1) Nosema
apis; and (2) Nosema ceranae (the more virulent of the two).
•
American Foulbrood Disease (AFD) is the most destructive of brood diseases. (Brood refers to
the egg, larval, and pupal stages in bee development.) AFD is caused by a bacterium (Paenibacillus larvae)
that exists in a spore or a vegetative stage; the disease is transmitted by the spore and the infected
brood is killed by the vegetative stage.
•
European Foulbrood Disease (EFD) is also caused by a bacterium (Melissococcus plutonius) and is
commonly found in colonies already weakened by lack of food or by other stressors.
•
Chalkbrood disease is caused by a fungus (Ascophaera apis); adult bees can detect and remove
diseased larvae; honey production may be reduced but the disease usually will not destroy a colony.
•
Amoeba disease is caused by the amoeba Malpighamoeba mellificae Prell; it infests the gut of honey
bees. Resistant spores (cysts) form in honey bees and can transmit the disease to other bees.
•
Other less common adult diseases include septicemia and spiroplasma. Both are caused by bacteria.
The former cause destruction of connective tissues; the latter infects the bees’ blood. They tend to
cause dysentery, and arise primarily from poor food and long periods of confinement.
•
Some common viral diseases affecting honey bees include: Deformed Wing Virus (DWV); Black
Queen Cell Virus (BQCV); Israeli Acute Paralysis Virus (IAPV); Acute Bee Paralysis Virus (ABPV);
Sacbrood Virus (SBV); Kashmir Bee Virus; and Chronic Bee Paralysis Virus (CBPV).
Other pests are mostly invertebrates, but some vertebrates are problematic locally. Among these pests are parasitic
mites, insects, and some larger animals.
•
Tracheal mites (Acarapis woodi) are parasitic mites that live inside the breathing organs of adult bees,
and eventually a newly mated female mite emerges from the old host bee.
•
Varroa mites, now known mostly for the vampire mite (Varroa destructor), are large mites that feed on
infested bees, resulting in disfigured, stunted adult bees and deformed larvae and pupae (varroosis).
•
Emerging threats such as the parasitic phorid fly (Apocephalus borealis), known to parasitize bumble
bees, has been found to also parasitize honey bees and can eventual y cause bees to abandon their hives.
•
Major insect enemies include the wax moth, and the small hive beetle.
•
Minor insect enemies include assassin and ambush bugs, robber flies, mantids, wasps, and dragonflies.
•
Various vertebrate pests include skunks, raccoons, bears, and mice.
One competitor deserves mention—the introduced Africanized honey bee. This bee is also a honey bee (Apis
mellifera) but of a different strain from those imported from Europe. They are good foragers, but the colonies are
more difficult to manage than the domestic European bee; they are sometimes called “kil er bees” although an
individual bee’s sting is no more severe than that of a European bee. They were accidentally released in Brazil decades
ago and have spread into the southern United States.
Sources: D. Sammataro and A. Avitabile, The Beekeepers Handbook, 4th Edition, pp. 189-232; Beekeepers
Association of Northern Virginia, “Diseases, Parasites, Pests, and Predators,” presentation materials; and for phorid
flies, see A. Core, et al., “A New Threat to Honey Bees, the Parasitic Phorid Fly Apocephalus borealis,” PLoS ONE
7(1), January 3, 2012, http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0029639.
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Possible Role of Pesticides
The previous section lists a range of possible factors thought to be negatively affecting managed
and wild bee populations. Among the identified factors were bee pests and diseases, diet and
nutrition, genetics, habitat loss and other environmental stressors, beekeeper issues, and
pesticides, as well as possible negative effects of cumulative, multiple exposures and/or the
interactive effects of each of these factors.
In response to congressional requests, this section examines in greater detail the potential role of
pesticides, providing a summary of selected, readily available data and reviews of the scientific
literature. This focus on the potential role of pesticides is not intended to imply that pesticides are
as important or more important in influencing the health and wellness of bee colonies as
compared with other identified factors influencing bee health; the relative importance of
pesticides in U.S. or global bee health is unknown and a subject of numerous research projects,
some of which are discussed below. In addition, this section summarizes general information
about the nature of pesticides, pesticide uses, and pesticide regulation in the United States, as well
as more specific information about the registration status of a class of pesticides known as
neonicotinoids.
Pesticides and Pesticide Law
Pesticides are broadly defined in U.S. law as chemicals and other products used to kill, repel, or
control pests.53 Familiar examples include pesticides used to kill insects (insecticides) and weeds
(herbicides) that can reduce the yield, and sometimes harm the quality, of agricultural crops,
ornamental plants, forests, wooden structures (e.g., through termite damage), and pastures. But
the broad legal definition of “pesticide” also applies to products with less familiar “pesticidal
uses.” For example, substances are pesticides when used to control mites, mold, mildew, and
other nuisance growths in hives or on equipment. The term also applies to disinfectants and
sterilizing agents, animal repellents, rat poison, and many other substances. An estimated 18,000
pesticide products are currently in use in the United States.54 Pesticides vary greatly in toxicity,
persistence in the environment, and ability to bioaccumulate up the food chain, as well as in the
range of plants and animals that are likely to be affected in the event of exposure. Some are
practically nontoxic to some species but exquisitely toxic to other species.
Statutory Framework
All pesticides are regulated by EPA under the authority of the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA), but approximately 5,800 pesticide products used in food production
also are regulated under the Federal Food, Drug, and Cosmetic Act (FFDCA), Section 408.
FIFRA requires EPA to regulate the sale and use of pesticides in the United States through
product registration and labeling. EPA is required to regulate so as to prevent unreasonable
adverse effects on people and the environment, taking into account the costs and benefits of
various pesticide uses. FIFRA prohibits sale of any pesticide in the United States unless it is
53 Federal Insecticide, Fungicide, and Rodenticide Act, Section 2(u). 7 U.S.C. 136-136y. For more detailed information
about pesticide laws and regulations, see CRS Report RL31921, Pesticide Law: A Summary of the Statutes.
54 S. Kaiser, EPA, personal communication with CRS staff, December 16, 2011.
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registered (licensed) and labeled to indicate approved uses and restrictions. It is a violation of the
law to use a pesticide in a manner that is inconsistent with the label instructions. EPA registers
each pesticide product for each approved use. For example, a product may be registered for use
on bee hives to control mites or as a seed treatment for corn. In addition, FIFRA requires EPA to
reregister pesticides first registered prior to 1984 and to review all registered pesticides
periodically on a 15-year cycle based on new data that meet current regulatory and scientific
standards.
For the 600 or more pesticides (i.e., active ingredients) registered for use in food production,
section 408 of the FFDCA authorizes EPA to establish maximum allowable residue levels (also
known as “tolerances”) to ensure that human exposure to the pesticide ingredients in food and
animal feed will be “safe.”55 A “safe” tolerance is defined in the law as a level at which there is “a
reasonable certainty of no harm” from the exposure, even when considering total cumulative and
aggregate pesticide exposure of children. (This standard also is used in registering pesticides for
residential uses.) Under the FFDCA, foods (or animal feeds) with a residue of a pesticide
ingredient for which there is no tolerance established, or with a residue level exceeding an
established tolerance limit, are declared “unsafe” and “adulterated”; such foods cannot be sold in
interstate commerce or imported to the United States. Pesticides may not be registered under
FIFRA for use on food crops unless tolerances (or exemptions) have been established under the
FFDCA.
Registration Process
When pesticide manufacturers apply to register an “active” ingredient for a pesticide, a
commercial pesticide product, or a new use of a registered pesticide under FIFRA Section 3, EPA
requires them to submit scientific data on toxicity and behavior in the environment. EPA may
require data from any combination of more than 100 different tests, depending on the potential
toxicity of active and inert ingredients and degree of exposure. To register a pesticide for use on
food, EPA also requires applicants to determine the amount of residue that could remain on crops,
as well as on (or in) food products (such as corn syrup), assuming that the pesticide product is
applied according to the manufacturers’ recommended rates and methods. Based on the data
submitted, EPA determines whether and under what conditions a proposed pesticide use would
present an unreasonable risk to human health or the environment, and, for a food or residential
use, whether its use would be safe. Some features of pesticides that might affect registration
decisions include the specificity of the pesticide for the targeted pest, its toxicity to people who
apply it, its tendency to persist in the environment over time, and its ability to bioaccumulate in
animals higher in the food chain. EPA specifically takes into account unintended harm to bees and
available information for other nontargeted insects in its registration decisions. EPA requires
studies to determine acute (short-term) toxicity of a pesticide on individual bees when they come
into body contact with pesticide residue. EPA also collects reports on bee-kill incidents. If a
pesticide appears to be very toxic to bees, EPA may require long-term studies of its effects.
55 Ingredients in pesticide products are categorized as active or inert. Active ingredients are those that are intended to
control the pest, while inert ingredients, now generally known as “other ingredients,” are used to deliver the active
ingredients effectively to the pest. Other ingredients often are solvents or surfactants and often comprise the bulk of the
pesticide product. Some inerts are known to be toxic, some are known to be harmless, and others have unknown
toxicity.
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If the risk is determined to be unreasonable or unsafe, EPA attempts to mitigate the risk by
adjusting requirements on the label (for example, requiring a buffer zone around lakes and
streams or requiring personal protective equipment for pesticide handlers). If the risk remains
unreasonable or unsafe, EPA will refuse to register the pesticide. If the risk is determined to be
reasonable and safe, registration is granted and the agency specifies the approved uses and
conditions of use, including safe methods of pesticide storage and disposal, which the registrant
must explain on the product label. EPA can and often does require specific application methods to
be printed on the product label to minimize environmental damage. For example, the label
sometimes requires that application of certain pesticides occur when bees are not foraging, when
there is little wind, or in a granular form or as a seed coating rather than aerially, in order to
minimize spray drift off property. Pesticide registrations are reviewed at least once every 15 years
to consider new scientific information and may be reviewed at any time in response to reports of
adverse effects and possible unreasonable risks from use of particular pesticides.
Exposure to Pesticides
Beekeepers use pesticides registered for the control of bacteria, fungi, mites, and other bee pests.
These are meant to protect bees from diseases. These pesticides are applied within and in the
vicinity of hives. Some common pesticides applied deliberately to hives include formic acid,
thymol, coumaphos, and fluvalinate.
Bees also sometimes are exposed to pesticides accidentally, either when pesticides are misused or
misapplied, or when used according to label directions to control pests in areas frequented by
bees, for example, alongside roads or rights of way for the control of weeds, trees, or other pests;
on or near commercial farm crops; or on or near fields, lawns, and gardens to control fleas, ticks,
weeds, grubs, mosquitos, or other adult insects. Figure 1 illustrates some significant paths of
exposure to pesticides applied as a spray or as a soil or seed treatment (systemic) for bees. If bees
happen to fly through a newly treated field or dust clouds from planting of seeds coated with
pesticide, or if they are orally exposed to pesticide in food or water, and if exposure is high
enough, bees may be sickened or die from pesticide exposure. (See summaries of specific studies
below.)
Impacts of Pesticides on Bee Health
As explained above, little is known about the health over time of native bees in the United States.
The health of managed honey bees is better characterized, but still somewhat uncertain.
Therefore, it is not appropriate at this time to conclude there has been a general and significant
decline in native bees, or to attribute global or even North American declines in the health of any
particular species of bee either native or managed bee species to pesticides. On the other hand,
pesticides are known to have some adverse local impacts on honey bees and some native bees.
Widespread use of herbicides reduces habitat available to bees;56 many pesticides are known to be
acutely toxic to bees, given sufficient levels of exposure; and some reports of local bee kill
incidents have been well documented. Laboratory research has shown lethal and sub-lethal effects
on individual bees associated with exposure to numerous pesticides. According to research cited
56 J.H. Cane and V.J. Tepedino, 2001, “Causes and extent of declines among native North American invertebrate
pollinators: Detection, evidence, and consequences,” Conservation Ecology, v. 5, n. 1, p. 1,
http://www.ecologyandsociety.org/vol5/iss1/art1/.
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by the NRC, “The application of pesticides, especially insecticides used to control crop pests,
kills or weakens thousands of honey bee colonies in the United States each year.”57 Nevertheless,
the NRC concluded in its 2007 report that local bee kills “likely have not contributed
significantly to the recent national decline in colony populations” [emphasis added].58
Figure 1. Major Routes of Exposure of Foraging Bees to Pesticides
Source: European Food Safety Authority (EFSA), “Scientific Opinion on the science behind the development of
a risk assessment of Plant Protection Products on bees (Apis mellifera, Bombus spp. and solitary bees),” Figure 3.1,
EFSA-Q-2011-00417, May 2012, http://www.efsa.europa.eu/en/efsajournal/pub/2668.htm.
Five years after the NRC issued its report, generalizations about the relative importance of
pesticides for global bee health still cannot be drawn from available data, given the disparate
study designs and results. Moreover, although research has been and continues to be conducted,
most scientists have focused on a single pesticide or pathogen at a time and consideration of
interactions has been minimal. A 2010 article by a group of well-known researchers explains:
Attempts to correlate global bee declines or CCD with increased pesticide exposures alone, have
not been successful to date … Pesticide interactions among various mixtures as well as with other
stressors including Varroa and Nosema, IAPV, beneficial hive microbes, and impacts on bee
57 C.A. Johansen and D.F. Mayer, 1990, Pollinator Protection, A Bee and Pesticide Handbook.
58 2007 NRC study, p. 79.
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immune systems all require further study. It seems to us that it is far too early to attempt to link or
to dismiss pesticide impacts with CCD.59
Even with respect to pesticides known as neonicotinoids (see below), experts disagree about their
potential effect on bee health; while some find that dietary neonicotinoids do not appear to be
implicated in overall decline of honey bee populations,60 others attribute unusual bee
disappearances and deaths mostly to use of clothianidin (a neonicotinoid) on sunflowers and
corn.61 A 2010 research paper argues that experts and beekeepers may be arguing past each other,
changing the definition of the problem depending on the audience. Some French researchers have
concluded that at least some French stakeholders have intentionally employed changing
definitions deliberately to confuse public understanding.62
This section summarizes selected recent studies that have raised questions about the risk to bees
posed by chronic exposure to neonicotinoids and certain other pesticides, particularly during the
spring planting season.
Generic Pesticide Research
Scientists have tested samples of beebread,63 trapped pollen,64 brood nest wax,65 beeswax
foundation,66 and adult bees and brood and found a broad range of pesticides, including miticides,
fungicides, insecticides, and herbicides.67 Both healthy and unhealthy hives were examined, but
no patterns were identified that might point to a particular pesticide or class of pesticides directly
affecting bee health.
These same scientists noted that the doses of individual pesticides found in bees were not lethal,
but researchers remained concerned about possible chronic problems caused by long-term
exposure and possible additive or synergistic effects of exposure to the combinations of pesticides
found.68 Studies have found synergistic adverse effects on honeybees exposed chronically to
sublethal concentrations of a pesticide (fipronil or imidacloprid) and Nosema.69
59 C.A. Mullin, M. Frazier, J.L. Frazier, et al., 2010, “High levels of miticides and agrochemicals in North American
apiaries: Implications for honey bee health,” PLoS ONE, v. 5, n. 3, p. e9754, http://www.plosone.org/article/
info%3Adoi%2F10.1371%2Fjournal.pone.0009754.
60 J. E. Cresswell, N. Desneux, and D. vanEngelsdorp, 2012, “Dietary traces of neonicotinoid pesticides as a cause of
population declines in honey bees: an evaluation by Hill’s epidemiological criteria,” Pest Management Science, v. 68,
pp. 819-827.
61 L. Maxim and J.P. van der Sluis, 2010, “Expert explanations of honeybee losses in areas of extensive agriculture in
France: Gaucho® compared with other supposed causal factors,” Environmental Research Letters, v. 5, 014006,
http://stacks.iop.org/ERL/5/014006.
62 Ibid.
63 Beebread is a pollen mixture stored in honeycomb cells and used with honey by bees as food. Beebread provides
nutrition for the queen and brood.
64 Trapped pollen refers to pollen collected at the entrance to the hive, removed from bees with the use of a trap.
65 This is wax originating in the area of the hive where brood is reared.
66 Foundation is the hexagonal sheets of wax and or wax/plastic combination that serves as a basis for comb
construction by honey bees.
67 C.A. Mullin, M. Frazier, J.L. Frazier, et al., 2010, “High levels of miticides and agrochemicals in North American
apiaries: Implications for honey bee health,” PLoS ONE, v. 5, n. 3, p. e9754.
68 Ibid.
69 J. Aufauvre, D.G. Biron, C. Vidau, et al. 2012, “Parasite-insecticide interactions: A case study of Nosema ceranae
(continued...)
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Pesticide products include ingredients other than the “active” ingredients which generally receive
less scrutiny during registration. Some of these “inerts” are surfactants which are intended to
improve delivery of the active ingredient to the target pest. A 2012 study looked at the impact on
bee health of three categories of inerts, also known as adjuvants: nonionic surfactants, crop oil
concentrates, and organosilicone surfactants.70 Bee behavior was adversely affected after
ingestion of 20 micrograms (µg) of organosilicone surfactant. Nonionic adjuvants also had a
small effect, while the crop oil concentrates were inactive, according to the scientists.71
Research on Neonicotinoid Pesticides
Neonicotinoids comprise a class of pesticides (that is, active ingredients) that have come under
considerable scrutiny with respect to their potential effects on bee health due to an incident of
misuse (that is, use not in accord with the pesticide label) of one neonicotinoid, imidacloprid, in
Germany72 that resulted in a large bee kill and widespread beekeeper concerns about use of
another neonicotinoid, clothianidin, and its impact on bees in France.73 Neonicotinoids are
systemic pesticides that, regardless of application method (spray, drip irrigation, granular
spreading, or seed coating), once taken into the plant migrate into all parts, including flowers,
pollen, and nectar.74 In the United States, some of the most commonly applied neonicotinoids
include imidacloprid, clothianidin, and thiamethoxam, which are sold by such tradenames as
Admire®, Acceleron®, Axcess®, Attendant®, Belay®, Cruiser®, Gaucho®, Nitro Shield®,
Poncho®, and Trimax Pro®. According to scientists at Bayer Crop Science, neonicotinoids
accounted for almost 25% of the global pesticide market, and imidacloprid was the largest selling
insecticide in the world in 2009.75
Exposure to Neonicotinoids
Bees can be exposed to neonicotinoids in many ways. A team of researchers recently reported that
they had identified multiple routes of exposure to low levels of neonicotinoids for honey bees
living and foraging near agricultural fields planted with corn or soybeans.76 The highest potential
(...continued)
and fipronil synergy on honeybee,” Scientific Reports 2, 326; C. Vidau, M, Diogon, J. Aufauvre, et al., 2011,
“Exposure toe sublethal doses of fipronil and thiacloprid highly increases mortality of honeybees previously infected
by Nosem ceranae,” PLoS ONE, v. 6, n. 6, p. e21550; and C. Alaux, J. Brunet, C. Dussaubat, et al., 2012, “Interactions
between Nosema microspores and a neonicotinoid weaken honeybees (Apis mellifera),” Environmental Microbiology,
v. 12, n. 3. pp. 774-782.
70 T. J. Ciarlo, C. A. Mullin, James L. Frazier, et al., 2012, “Learning impairment in honey bees caused by agricultural
spray adjuvants,” PLoS ONE, v. 7, n. 7, p. e40848.
71 Ibid.
72 D. vanEngelsdorp and M.D. Meixner, 2010, “A historical review of managed honey bee populations in Europe and
the United States and factors that may affect them,” Journal of Invertebrate Pathology, v. 103, Supplement 1, p. S80-S
95.
73 L. Maxim and J.P. van der Sluis, 2010, “Expert explanations of honeybee losses in areas of extensive agriculture in
France: Gaucho® compared with other supposed causal factors,” Environmental Research Letters, v. 5,
http://stacks.iop.org/ERL/5/014006.
74 UNEP, Global Honey Bee Colony Disorders and Other Threats to Insect Pollinators, 2010.
75 P. Jeschke, R. Nauen, M. Schindler, ,et al., 2011, “Overview of the status and global strategy for neonicotinoids,”
Journal of Agricultural and Food Chemistry, v. 59, pp. 2897-2908.
76 C. Krupke, G. Hunt, B. Eitzer, et al., 2012, “Multiple routes of pesticide exposure for honey bees living near
agricultural fields,” PLoS ONE, v. 7, n. 1, p. e29268.
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exposure to the pesticides appeared to occur during planting season, when bee mortality was also
high, according to the researchers. Clothianidin was found in about half the corn pollen they
sampled, thiamethoxam in three of twenty samples, and fungicides in all pollen samples.
Clothianidin was detected in all dead and dying bees but in no healthy bees. Although corn is not
an insect-pollinated crop, this research demonstrated that bees forage for corn pollen and take it
back to the hive.77 About half the hive pollen sampled came from corn in this study. In addition,
these scientists documented high levels of pesticide in exhaust material from mechanical planters
when pesticides and talc were used to coat seeds, and found clothianidin in soil samples from
planted and unplanted fields.78
Other studies have measured neonicotinoids in pollen and nectar of canola (rape), 79 corn,80,81 and
sunflowers82,83 grown from seed coated with pesticides. Levels found were below those known to
be acutely toxic. However, very recent studies have found that imidacloprid and thiamethoxam
concentrations in nectar were greater in squash84 and pumpkin flowers85 when insecticide was
applied to the soil than they were in canola and sunflowers grown from seed treated with
neonicotinoids. Researchers also found metabolites of imidacloprid and thiamethoxam
(clothianidin) in all parts of squash plants, along with the parent compound.86 Krupke et al. found
levels of neonicotinoids in bee-collected corn pollen that were similar to levels of imidacloprid
determined by other scientists to have sublethal effects potentially affecting colony health.87
(Some of these studies on the effects of neonicotinoid exposure are described below.)
Another potential source of exposure was suggested by Chengsheng Lu and colleagues, who
showed that bees might be exposed to neonicotinoids in the corn syrup they are sometimes fed
77 Ibid.
78 Ibid.
79 G. C. Cutler and C. D. Scott-Dupree, 2007, “Exposure to clothianidin seed-treated canola has no long-term impact on
honey bees,” Journal of Economic Entomology, v. 100, pp. 765-772.
80 J. M. Bonmatin, P. A. Marchand, R. Cahvet, et al., 2005, “Quantification of imidacloprid uptake in maize crops,”
Journal of Agricultural and Food Chemistry, v. 53, pp. 5336-5341.
81 C. Krupke, G. Hunt, B. Eitzer, et al., 2012, “Multiple routes of pesticide exposure for honey bees living near
agricultural fields,” PLoS ONE, v. 7, n. 1, p. e29268.
82 F. M. Laurent and E. Rathahao, 2003, “Distribution of [14C] imidacloprid in sunflowers (Helianthus annuus L.) following
seed treatment,” Journal of Agricultural and Food Chemistry, v. 51, pp. 8005-8010.
83 R. Schmuck, R. Schoning, A. Stork, et al., 2001, “Risk posed to honeybees (Apis mellifera L, Hymenoptera) by an
imidacloprid seed dressing of sunflowers,” Pest Management Science, v. 57, pp. 225-238.
84 K. A. Stoner and B. D. Eitzer, 2012, “Movement of soil-applied imidacloprid and thiamethoxam into nectar and
pollen of squash (Cucurbita pepo),” PLoS ONE, v. 7, n. 6, p. e39114.
85 G. P. Dively and A. Kamel, 2012, “Insecticide residues in pollen and nectar of a cucurbit crop and their potential
exposure to pollinators,” Journal of Agricultural and Food Chemistry, v. 60, pp. 4449-4456.
86 K. A. Stoner and B. D. Eitzer, 2012, “Movement of soil-applied imidacloprid and thiamethoxam into nectar and
pollen of squash (Cucurbita pepo),” PLoS ONE, v. 7, n. 6, p. e39114.
87 For example, see H.V.V. Tomé, G.F. Martins, M. August, et al., 2012, “Imidacloprid-induced impairment of
mushroom bodies and behavior of the native stingless bee Melipona quadrifasciata anthidioides,” PLoS ONE, v. 7, n.
6, p. e38406; D.M. Eiri and J. C. Nieh, 2012, “A nicotinic cacetylcholine receptor agonist affects honey bee sucrose
responsiveness and decreases waggle dancing,” The Journal of Experimental Biology, v. 215, n. 12, pp. 2022-2029; A.
Decourtye, E. Lacassie, and M. Pham-Delegue, 2003, “Learning performances of honey bees (Apis mellifera L.) are
differentially affected by imidacloprid according to the season.” Pest Management Science, v. 59, pp. 269-278; or V.
Mommaerts, S. Reynders, J. Boulet, et al., 2010, “Risk assessment for side-effects of neonicotinoids against
bumblebees with and without impairing foraging behavior,” Ecotoxicology, v. 19, pp. 207-215.
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during the winter by beekeepers.88 However, they did not sample corn syrup actually fed to bees,
but rather showed that bees would consume sufficient imidacloprid to produce toxic sublethal
effects if they were provided contaminated corn syrup in the hive. Research by DeGrandi-
Hoffman, Sammataro, and Simonds found no pesticides in samples of high-fructose corn syrup
obtained from three major suppliers.89
Effects on Bee Health
Neonicotinoids are insect neurotoxins that vary in strength of effect exerted on honey bees.90
They are related to nicotine and were developed as an alternative to highly toxic (to humans)
organophosphate insecticides such as methyl parathion.91 Effects on individual bees may be lethal
or sublethal depending on dose and other conditions of exposure. For example, EPA has
determined that clothianidin “has the potential to be highly toxic on both a contact and an oral
basis” to honey bees.92 In addition, EPA has reported that one honey bee field study submitted to
the agency indicates that “mortality, pollen foraging activity, and honey yield were negatively
affected by residues of clothianidin,” but the residue levels were not reported.93
Acute effects also have been demonstrated in another recent field study. It showed that honey
bees can be killed by exposure to pesticide-contaminated talc if they fly through dust clouds
associated with planting,94 but mortality appears to depend on high levels of humidity.95
In response to reports that honey bees are disappearing and causing hives to collapse, recent
studies of the impacts of exposure to imidacloprid and other neonicotinoids96,97 have focused
more on their potential to affect complex behaviors in insects, including flight, navigation,
olfactory memory, recruitment, foraging, and coordination.98 One study has reported sublethal
88 Chensheng Lu, K.M. Warchol, and R.A. Callahan, 2012, “In situ replication of honey bee colony collapse disorder,”
Bulletin of Insectology, v. 65, n. 1 99-106.
89 G. DeGrandi-Hoffman, D. Sammataro, and R. Simonds, 2012, “Are agrochemicals present in high fructose corn syrup fed
to honey bees (Apis mellifera L.)?” Jurnal of Apicultural Research, v. 51, n. 4, pp. 371-372.
90 D. Laurino, M. Porporato, A. Patetta, et al., 2011, “Toxicity of neonicotinoid insecticides to honey bees: laboratory
tests,” Bulletin of Insectology, v. 64, n. 1, pp. 107-113.
91 S. P. Bradbury, Office of Pesticide Programs, Letter to Peter T. Jenkins, Center for Food Safety and International
Center for Technology Assessment, July 17, 2012. Hereafter referred to as Bradbury response to citizen petition.
92 J. DeCant and M. Barrett, 2010, “Environmental Fate and Ecological Risk Assessment for the Registration of
CLOTHIANIDIN for Use as a Seed Treatment on Mustard Seed (Oilseed and Condiment) and Cotton,” EPA/Office of
Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, DC, p. 14.
93 Ibid.
94 A. Tapparo, D. Marton, C. Giorio, et al., 2012, “Assessment of the environmental exposure of honeybees to
particulate matter containing neonicotinoid insecticides coming from corn coated seeds,” Environmental Science &
Technology, v.46, pp. 2592-2599.
95 V. Girolami, M. Marzaro, L. Vivian, et al., 2012, “Fatal powdering of bees in flight with particulates of
neonicotinoids seed coating and humidity implication,” Journal of Applied Entomology, v. 136, n. 1-2, pp. 17-26.
96 D. Cox-Foster and D. vanEngelsdorp, “Solving the Mystery of the Vanishing Bees,” Scientific American, March 31,
2009; Northwest Coalition for Alternatives to Pesticides, “Imidacloprid, Fact Sheet,” Journal of Pesticide Reform,
Spring 2001, http://www.pesticide.org/imidacloprid.pdf; and Apiculteurs de France, “Composite Document of Present
Position Relating to Gaucho, Sunflower and Bees,” http://www.beekeeping.com/articles/us/gaucho/
manifestation_paris_us.htm.
97 Joe Cummins, “Neoniccotinoid insecticides used in seed dressing may be responsible for the collapse of honeybee
colonies,” April 24, 2007, http://www.organicconsumers.org/articles/article_4972.cfm.
98 BNA’s International Environmental Law Committee Newsletter, vol. 11, no. 1, February 2009,
(continued...)
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effects of neonicotinoid pesticides on honey bee foraging behavior that may impair the
navigational and foraging abilities of honey bees.99 Scientists at Bayer Crop Science argue that
the dose of thiamethoxam delivered to bees in this case was not “field-relevant.”100 At “field-
relevant” doses for sunflowers and canola (defined as 0.15 nanogram (ng) per bee of imidacloprid
or 0.05 ng/bee of clothianidin), Schneider et al. found no effect on foraging and homing behavior
of honey bees exposed to treated crops.101 The same study found, that “both substances led to a
significant reduction of foraging activity and to longer foraging flights at doses of 1.5 ng/bee of
imidacloprid or 0.5 ng/bee of clothianidin during the first three hours after treatment.”102
However, these latter numbers might be approaching “field relevant” numbers for neonicotinoids
in squash nectar and corn pollen (see discussion of exposure above), particularly when other
sources of exposure are considered and when pesticides are applied directly to soil.103
Other studies have found impaired brood development104 and increased rates of Nosema infection
in honey bees exposed to sublethal pesticide levels.105 Imidacloprid ingestion by stingless bee
larvae at rates above 0.0056 µg/bee decreased survival rates, negatively affected development of
a specific region of the bee brain called the mushroom body, and impaired walking behavior of
newly emerged adult worker bees.106 Scientists from Bayer Crop Science have criticized one of
the studies linking neonicotinoid exposure with Nosema infection because it was conducted in the
laboratory and not under field conditions.107
In another study, responsiveness to sucrose and waggle dancing (which communicates food
locations to nest mates) was adversely affected when honey bees ingested a few nanograms of
imidacloprid. The bees’ preference for greater sucrose concentrations dissipated within an hour of
ingestion.108
(...continued)
http://www.abanet.org/environ/committees/intenviron/newsletter/feb09/IELC_Feb09.pdf.
99 M. Henry, M. Beguin, F. Requier, et al., 2012, “A common pesticide decreases foraging success and survival in
honey bees,” Science, v. 336, n. 6079, pp. 348-350.
100 Bayer Crop Science, “Overview of recent publications on neonicotinoids and pollinators.” Paper received personally
from Jean Reimers (CropLife America), June 20, 2012.
101 C.W. Schneider, J. Tautz, B. Grünewald, et al., 2012, “RFID Tracking of sublethal effects of two neonicotinoid
insecticides on the foraging behavior of Apis mellifera.” PLoS ONE, v. 7, n. 1, p. e30023, http://www.plosone.org/
article/info%3Adoi%2F10.1371%2Fjournal.pone.0030023.
102 Ibid.
103 K. A. Stoner and B. D. Eitzer, 2012, “Movement of soil-applied imidacloprid and thiamethoxam into nectar and
pollen of squash (Cucurbita pepo),” PLoS ONE, v. 7, n. 6, p. e39114.
104 Judy Y. Wu, Carol M. Anelli, and Walter S. Sheppard, 2011, “Sub-lethal effects of pesticide residues in brood comb
on worker honey bee (Apis mellifera) development and longevity,” PLoS ONE v., 6, n. 2, p. e14720.
105 J.Y. Wu, M.D. Smart, C.M. Anelli, et al., 2012, “Honey bees (Apis mellifera) reared in brood combs containing high
levels of pesticide residues exhibit increased susceptibility to Nosema (Microsporidia) infection,” Journal of
Invertebrate Pathology, v. 109, pp. 326-329; and J. Pettis, D. vanEngelsdorp, J. Johnson, et al., 2012, “Pesticide
exposure in honey bees results in increased levels of the gut pathogen Nosema,” Naturwissenschaften, v. 99, pp. 153-
158.
106 H. V. V. Tomé, G. F. Martins, M. August, et al., 2012, “Imidacloprid-induced impairment of mushroom bodies and
behavior of the native stingless bee Melipona quadrifasciata anthidioides,” PLoS ONE, v. 7, n. 6, p. e38406.
107 Bayer Crop Science, “Overview of recent publications on neonicotinoids and pollinators.” Paper received personally
from Jean Reimers (CropLife America), June 20, 2012.
108 D. M. Eiri and J. C. Nieh, 2012, “A nicotinic cacetylcholine receptor agonist affects honey bee sucrose
responsiveness and decreases waggle dancing,” The Journal of Experimental Biology, v. 215, n. 12, pp. 2022-2029.
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Finally, in another recent experiment, 16 hives of honey bees were fed corn syrup treated with
imidacloprid. After 6 months, 15 of the 16 treated hives collapsed, while 4 untreated control hives
remained healthy.109
A few recent studies have looked at bumble bees. One found that bumble bee colonies exposed in
a laboratory to low levels of imidacloprid had a significantly reduced growth rate and an 85%
reduction in queen production relative to untreated colonies. 110 Another study found that
ingestion of low concentrations of neonicotinoids could adversely affect foraging behavior.111
Bayer Crop Science argues that these results were obtained “under artificial conditions and are in
conflict with” earlier studies.112
Neonicotinoid Registration Review at EPA
Neonicotinoid pesticide registrations currently are being reviewed by EPA. EPA’s website states:
The neonicotinoids are a class of insecticides with a common mode of action that affects the
central nervous system of insects, causing paralysis and death. All of the neonicotinoids were
registered after 1984 and were not subject to reregistration. Some uncertainties have been
identified since their initial registration regarding the potential environmental fate and effects of
neonicotinoid pesticides, particularly as they relate to pollinators. Data suggest that neonicotinic
residues can accumulate in pollen and nectar of treated plants and may represent a potential
exposure to pollinators. Adverse effects data as well as beekill incidents have also been reported,
highlighting the potential direct and/or indirect effects of neonicotinic pesticides. Therefore,
among other refinements to ecological risk assessment during registration review, the Agency
will consider potential effects of the neonicotinoids to honeybees and other pollinating insects.113
Review of clothianidin registrations began December 2011. EPA aims to review all
neonicotinoids as a group.114
In the process of reviewing registrations for neonicotinoids, EPA is revising its risk assessment
process. A letter from the Environmental Fate and Effects Division of the EPA Office of Chemical
Safety and Pollution Prevention explains:
The EPA is currently revising its process for assessing pesticide risks to bees to reflect
advancements in the state of the science that underlie bee exposure and effects assessments.
Interim guidance [EPA, 2011, Pesticides: Science and Policy, Interim Guidance on Honey Bee
109 Chensheng Lu, K.M. Warchol, and R.A. Callahan, 2012, “In situ replication of honey bee colony collapse disorder,”
Bulletin of Insectology, v. 65, n. 1 99-106.
110 P.R. Whitehorn, S. O’Connor, D. Goulson, et al. 2012, “Neonicotinoid pesticide reduces bumble bee colony growth
and queen production,” Science, v. 336, p. 351-352.
111 V. Mommaerts, S. Reynders, J. Boulet, et al., 2010, “Risk assessment for side-effects of neonicotinoids against
bumblebees with and without impairing foraging behavior,” Ecotoxicology, v. 19, pp. 207-215.
112 Bayer Crop Science, “Overview of recent publications on neonicotinoids and pollinators.” Paper received personally
from Jean Reimers (CropLife America), June 20, 2012.
113 EPA, Pesticides, Registration Review, Program Highlights, Groups of Related Pesticides Beginning Registration
Review, Neonicotinoids, May 9, 2012, http://www.epa.gov/oppsrrd1/registration_review/highlights.htm, Dec. 4, 2012.
114 The status of the review and relevant documents is available at http://www.regulations.gov (docket: EPA-HQ-OPP-
2011-0865). EPA review of imidacloprid registrations began December 2008 (docket: EPA-HQ-OPP-2008-0844). The
schedule for other reviews is at http://www.epa.gov/oppfead1/cb/ppdc/2012/may/session-9-reg-review-update.pdf.
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Data Requirements, http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/
terrestrial_biology_tech_team/honeybee_data_interim_guidance.pdf] on factors to consider when
evaluating exposure and effects to bees is available to ecological risk assessors. In 2012, the EPA
will present to a FIFRA Scientific Advisory Panel (SAP) a proposed process for quantifying risks
to honeybees and identifying exposure and effect studies needed to inform that process. Based on
input from the SAP, the EPA will incorporate its revised assessment process to quantify risks to
bees in a similar manner as that used to evaluate risks to other taxa.115
The draft risk assessment policy has been released to the public, and the materials distributed and
discussed at the SAP meeting are available in the regulatory docket (EPA-HQ-OPP-2012-0543).
On March 20, 2012, EPA received a citizen petition asking it to suspend registrations for the
insecticide clothianidin, among other demands.116 The petition and numerous supplemental
submissions of research reports and opinions are posted in the regulatory docket on the Internet at
http://www.regulations.gov. EPA responded in part to the petition on July 17, 2012. EPA denied
the request to suspend registrations “to prevent imminent harm” because the petitioners did not
meet the burden of proof for registration suspension. However, EPA plans to revisit this decision
and to evaluate the other demands in the near future as it reviews neonicotinoid registrations.
Author Contact Information
Linda-Jo Schierow
M. Lynne Corn
Specialist in Environmental Policy
Specialist in Natural Resources Policy
lschierow@crs.loc.gov, 7-7279
lcorn@crs.loc.gov, 7-7267
Renée Johnson
Specialist in Agricultural Policy
rjohnson@crs.loc.gov, 7-9588
115 EPA, Environmental Fate and Effects Division (EFED), EFED Response to Comments Submitted to the
Clothianidin Registration Review Docket (Docket ID: EPA-HQ-OPP-2011-0865), June 11, 2012, p. 3.
116 S.P. Bradbury, EPA Office of Pesticide Programs, Letter to Peter T. Jenkins, Center for Food Safety and
International Center for Technology Assessment, “Clothianidin Emergency Citizen Petition dated March 20, 2012,”
July 17, 2012, http://www.epa.gov/opp00001/about/intheworks/epa-respns-to-clothianidin-petition-17july12.pdf.
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