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Global Pollinator Decline: A Literature Review

Authors:
A scientific report about the current situation, recent findings and
potential solution to shed light on the global pollinator crisis
Global Pollinator Decline:
A Literature Review
G R ID
Europe
September 2007
UNEP/DEWA/GRID-Europe
11, Ch. Des Anémones
1219 Châtelaine
Geneva – Switzerland
Tel: (+41) 22.917.82.94
Fax: (+41) 22.917.80.29
Website: www.grid.unep.ch
Lead Authors
Stéphane Kluser and Pascal Peduzzi
Citation
Kluser S, Peduzzi P, (2007), ”Global Pollinator
Decline: A Litterature Review”, UNEP/GRID-
Europe. © UNEP 2007
Disclaimer
This analysis was conducted using global data
sets, the resolution of which is not suitable for in-
situ planning. UNEP and collaborators should in
no case be liable for misuse of the presented
results. The views expressed in this publication
are those of the authors and do not necessarily
reflect those of UNEP.
Acknowledgements
This review would not have been possible without
the close collaboration of David Duthie of the
UNEP-GEF Biosafety Unit who provided
resourceful articles and links. We also would like
to thank Ron Witt and Jaap van Woerden for their
advices, comments and review.
Cover photos credits:
Background: David L. Green
Bee: David Cappaert, Michigan State University
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1. Introduction
We are currently enduring the 6th mass extinction, losing between 1 - 10 % of biodiversity per decade1,
mostly as a result of habitat loss, pest invasion (exotics), pollution, over harvesting and disease2. Why care ?
Biodiversity losses aren’t only affecting natural ecosystems but also the services they provided and some of them
are vital for human societies amongst other the presence of oxygen into the atmosphere, renewing of soils (from
bacteria, worms, …) and pollination – the transfer of pollen from one flower to another – is critical to fruit and
seed production, and is often provided by insects and other animals on the hunt for nectar, pollen or other floral
rewards.
Until very recently, most farmers considered pollination as one of nature's many "free services", so taken for
granted that it has rarely figured as an "agricultural input" or even as a subject in agricultural science courses3.
This assumption has apparently become obsolete as these changes are already being illustrated, need to be
monitored and mitigated in the near future, posing threats to the integrity of biodiversity, global food webs and
even ultimately to human health.
The Food and Agriculture Organisation (FAO) of the U.N.4 estimates that of the slightly more than 100 crop
species that provide 90 percent of food supplies for 146 countries, 71 are bee-pollinated (mainly by wild bees),
and several others are pollinated by thrips, wasps, flies, beetles, moths and ot her insects. In Europe alone, 84% of
the 264 crop species are animal-pollinated and 4 000 vegetable species have their life assured thanks to the
pollination of the bees5. Pollinators are essential for the reproduction of many wild flowers and crops: for one out
of every three bites eaten, one can thank a bee, butterfly, bat, bird or other pollinator6. As Simon Potts, (University
of Reading) says: "The economic value of pollination worldwide is thought to be between £30 and 70 billion each
year" [i.e. 45 - 100 billions €]. Any loss in biodiversity is a matter of public concern, but losses of pollinating
insects may be particularly troublesome because of the potential effects on plant reproduction and hence on food
supply security. Many agricultural crops and natural plant populations are dependent on pollination and often on
the services provided by wild, unmanaged, pollinator communities7.
Several researches have highlighted the different factors leading to pollinators decline8 such as modern
agricultural practices and use of pesticides, habitat fragmentation, climate change, also to a lower extent lack of
floral diversity, competition from non-native species, diseases, predators and parasites. This literature review
seeks to update the state of knowledge on this issue, in light with the recent declines. The recent episode of
Colony Collapse Disorder (CCD) that is affecting north America where about a third of honey bees disappeared in
several months, shed a new light on the matter and is a reminder of the level of threat posed by the losses of
pollinators for both natural ecosystems and crops production. One latest finding about CCD highlighted a bee
disease called Israeli acute paralysis virus as strongly associated with the beekeeping operations that experienced
big losses, although members of the research team emphasized that they had not proved the virus caused the die-
offs.
2. Current pollinators declines
2.1. Status in Europe
A recent collaboration (2006) bet ween british and dutch scient ists showed that in the UK and the
Netherlands, a 70% drop of wild flowers that require insect pollination has been recorded as well as a shift in
pollinator community composition since the 1980s9. In UK, Stuart Roberts from the University of Reading points
out that pollinator species that were relatively rare in the past have tended to become rarer still, while the
1 Wilson E.O, 1999. “The Diversity of Life” (new edition). W.W. Norton & Company, Inc. New-York.
2 Wilcove, D.S., D. Rothstein, J. Dubow, A. Phillips, and E. Losos. 1998. Quantifying threats to imperiled species in the United States. BioScience 48:607-615.
3 Fo od and Agriculture Organisation of the U.N. at www.fao.org.
4 Idem
5 Williams, I.H., 1996. “Aspects of bee diversity and crop pollination in the European Union”. In The Conservation of Bees (Metheson, A. et al., eds), pp. 63–80, Academic Press.
6 Ingram M., Nabhan G. and Stephen Buchmann, 1996. “Global Pesticide Campaigner”, Vo lume 6, Number 4, December 1996.
7 Free, J.B., 1993. “Insect Pollination of Crops”, Academic Press
8 Cane, J. H. and V. J. Tepedino. 2001. “Causes and extent of declines among native North American invertebrate pollinators: detection, evidence, and conseq uences.
Conservation Ecology 5(1): 1. [online] URL: www.consecol.org/vol5/iss1/art1
9 Biesmeijer J.C., Roberts S. P. M. et al, 2006. “Parallel Declines in Pollinators and Insect-Pollinated Plants in Britain and the Netherlands”. Science: Vol. 313. no. 5785, pp. 351
354.
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commoner species have become even more widespread”. J. A. Thomas et al.10 have found that 71% of butt erfly
species have decreased and 3.4% became extinct over the past 20 years, illustrating the greatest net loss compared
to native vascular plants (28% decrease in 40 years) and birds (54% decrease in 20 years) of the same area in the
UK. Most species of non-migratory butterflies that reach the northern margins of their geographic ranges in
Britain have declined over the last 30 years (as they have elsewhere in northern Europe11).
2.2. Colony Collapse Disorder (CCD) in North America
Background
In North America, a significant decline in commercially managed honeybee colonies during the winter and
spring of 2006-2007 led to the losses of about one third of honeybees. This event is called Colony Collapse
Disorder (CCD). CCD has affected honeybees in 35 states of the United States. Some beekeepers report losses in
their colonies as high as 80 to 100 percent. If left unchecked, CCD has the potential to cause a $15 billion direct
loss of crop production and $75 billion in indirect losses (see following details and 12).
About 1/3 of the North-American diet comes from food – fruits, vegetables, seeds and nuts – that rely on
animal pollinators, which include beetles, butterflies, flies, bats, hummingbirds and bumblebees13. Honey bees are
essential crops pollinators in the United States: they are indispensable farmhands, pollinating some 95 kinds of
fruits and veget ables14. In 2000, the value of American crops pollinated by bees was estimated to be US$ 14.6
billion15.
“[] latest decline are part of a larger trend, with honey bee colonies down 50% in the past 50 years” said
Senator Barbara Boxer16 (US Senate Environment Committee chair). "Because native and honey bees pollinate so
many crops, this decline, if not stopped, could impact many crops dependent on animal pollination and cause both
increased prices and shortages of many food crops including almonds, avocados, cranberries, apples, and
soybeans" said Boxer.
According to the Committee on the Status of Pollinators in North America17, the introduction of parasites
particularly Varroa destructor and the varro a m ite have clearly contributed to the reduction of honey bee. They
also highlight that in early 2005 a change in regulation led to the first importation from outside north America of
honey bees since 1922, thus increasing the risk of pest and parasite introduction. There are other possibilities such
as “antibioticresistant pathogens (American foulbrood); pesticide-resistant mites; and the encroachment of
Africanized honey bees, particularly in the South Eastern United States17.
The symptoms of CCD
Colony Collapse Disorder (CCD) is described as a multifactorial syndrome which has been leading to low
number of adult bees in the hives which still held food supplies and immature bees (brood). The loss of bees
seems to be the sudden early death, in the field, of large numbers of adult workers18. In 2006-2007, some 29% of
577 beekeepers across the country reported CCD and losses of up to 75% of their colonies19.
The following sy mpt oms were report ed20:
- Complete absence of adult bees in colonies, with no or little build up of dead bees in the colonies.
- Presence of capped brood.
- Presence of food stores, both honey and bee bread
In collapsing colonies:
10 Thomas J. A., Telfer M. G. et al, 2004. “Comparative Losses of British Butterflies, Birds, and Plants and the Global Extinction Crisis”. Science: Vol. 303. no. 5665, pp. 1879
1881.
11 Warren M. S., Hill J. K et al, 2001. “Rapid responses of British butterflies to opposing forces of climate and habitat change”. Nature, Volu me 414, Iss ue 6859, pp . 65-6 9.
12 Oldroyd B. P., 2007. “What's Killing American Honey Bees?”, PLoS Biol 5(6): e168 doi:10.1371/journal.pbio.0050168.
13 Holden C., “Report Warns of Looming Pollination Crisis in North America”, Science 20 October 2006 314: 397 [DOI: 10.1126/science.314.5798.397] (in News of the Week)
14 Stokstad E., “The Case of the Empty Hives”, Science 18 May 2007 316: 970-972 [DOI: 10.1126/science.316.5827.970] (in News Focus)
15 Morse R.A., Calderone N.W., 2000. “The value of honey bees as pollinators of U.S. crops in 2000”.
16 Senator Barbara Boxer, a California Democrat, introduced on Friday June 29 2007 “The Pollinator Protection Act”, a bill to increase funding for research on honey bees and
nat ive p o llin ators , whos e nu mbers h av e been in decli ne in recent decad es.
17 Status of Pollinators in North America, summary, National Academy of Sciences (June 2007), http://books.nap.edu/catalog/11761.html, p.4
18 “Colony Collapse Disorder (CCD) Working Group: Summary of purpose and responsibility” at http://maarec.cas.psu.edu/pressReleases/CCDSummaryWG0207.pdf
19 Stokstad E., “The Case of the Empty Hives”, Science 18 May 2007 316: 970-972 [DOI: 10.1126/science.316.5827.970] (in News Focus)
20 Fall Dwindle Disease: A preliminary report, December 2006. http://www.ento.psu.edu/MAAREC/pressReleases/FallDwindleUpdate0107.pdf
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- Insufficient of workforce, mostly consisting in young adult s bees
- The queen is present
- The cluster is reluctant to consume provided feed, such as sugar syrup and protein supplement.
CCD Causes
According to Frazier et al. (2007) , the causes of CCD are not yet known. The potential causes investigated
by “The CCD working group are, but are not limited to:
Chemical residue/contamination in the wax, food stores and bees. Due to the evolution of resistances to
chemicals of mites and other pathogens, beekeepers may be increasing dose rates or trying cocktails of chemicals
exposing commercial honey bees to levels of chemical residue that are inimical to worker longevity.
Pathogens in the bees and brood. For example, European Foul Brood (caused by Mellisococcus pluton),
and American Foul Brood (caused by Paenibacillus larvae) on larvae and pupae,
Parasi te load in the bees and brood. For example, Varroa destructor on adult bees.
Nutritional fitness of the adult bees
Level of stress in adult bees as indicated by stress induced proteins
Lack of genetic diversity and lineage of bees making them more vulnerable to the development of
epidemics ,
Examples of topics that The CCD working group is not currently investigating:
Agricultural insecticides. American agricultural systems are dependent on the use of pesticides. Where
insecticides are used, honey bee losses are common, and where bees are required for pollination, careful
management is required to minimize bee losses.
Changed a gri cul tural practise. Due to reduced honey yields nation-wide, beekeepers seek alternative
income beyond honey production (for example colonies for almond pollination, crop that is totally dependant on
bee pollination. Anecdotal evidence suggest s that CCD is more common in businesses in which bees are trucked
large distances and rented for pollination.
GMO crops. Some GMO crops, specifically Bt Corn have been suggested as a potential cause of CCD .
While this possibility has not been ruled out, the weight of evidence reported here argues strongly that the current
use of Bt crops is not associated with CCD.” 28 CCD symptoms do not fit what would be expected in Bt affected
organisms and there is no strong evidence that GM crops cause acute toxicity to honey bees , ,. For this reason
GMO crops are not a “top” priority at the moment. According to Galen P. Dively (2007).
Radiation transmitted by cell towers: The distribution of both affected and non-affected CCD apiaries
does not make this a likely cause. Also cell phone service is not available in some areas where affected
commercial apiaries are located in the west. For this reason, it is currently not a top priority.
21 Frazier, M., D. v anEngelsdor, and D. Caro, (2007), Edited by the CCD working group at www.agr.state.il.us/programs/bees/CCD.pdf
22 Bailey L (1983) Melissococcus pluton, the cause of European foulbrood of honey bees (Apis spp.). J Appl Bacteriol 55: 65–69.
23 Ashiralieva A, Genersch E (2006) Reclassifi cation, genotypes and virulence of Paenibacillus larvae, the etiological agent of American foulbrood in honeybees - a review.
Apidologie 37: 411–420.
24 Oldroyd BP (1999) Coevolution while you wait: Varroa jacobsoni, a new parasite of western honeybees. Trends Ecol Evol 14: 312– 31 5.
25 van Baalen M, Beekman M (2006) The costs and benefi ts of genetic heterogeneity in resistance against parasites in social insects. Am Nat 167: 568–577.
26 Evans JD, Aronstein K, Chen YP, Hetru C, Imler JL et al. (2006) Immune Pathways and defence mechanisms in honey bees Apis mellifera. Ins Mol Biol 15: 645656.
27 O’Callaghan M, Glare TR, Burgess EPJ, Malone LA (2005) Effects of plants genetically modifi ed for insect resistance on nontarget organisms. Ann Rev Ent 50: 271–292.
28 Dively, G., P., (2007), Summary of Research on the Non-Target Effect of BT Corn Pollen on Honeybees http://www.ento.psu.edu/MAAREC/CCDPpt/NontargeteffectsofBt.pdf
29 Malone LA, Pham-Delegue MH (2001) Effects of transgene products on honey bees (Apis mellifera) and bumblebees (Bombus sp.). Apidologie 32: 287–304.
30 Huang ZY, Hanley AV, Pett WL, Langenberger M, Duan JJ (2004) Field and semifi eld evaluation of impacts of transgenic canola pollen on survival and development of
wo rker honey b ees. J Econ Ent 97: 15 17–1 523.
31 Malone LA, Burgess EPJ, Stefanovic D (1999) Effects of a Bacillus thuringiensis toxin, two Bacillus thuringiensis biopesticide formulations, and a soybean trypsin inhibitor on
honey bee (Apis mellifera L.) survival and food consumption. Apidologie 30: 465–473.
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Cool brood. If the brood is incubated a little outside the ± 0.5 °C of 34.5 °C range (nest temperature
maintained by bees), the resulting adults are normal physically, but show deficiencies in learning and memory32,33.
If colonies were unable to maintain optimal brood nest temperatures, CCD-like symptoms might be apparent.
The working group on CCD is now concentrating on three different hypot heses 34:
- Reemerging pathogens responsible for CCD. It has become clear in recent years that many pathogens
have the ability to impair the immune defences of their hosts.
- Stresses working together to weaken bee colonies and allowing stress-pathogens to cause final collapse.
For example stresses are encountered by bee colonies that are part of migratory operations. As a result of
the migratory process, multiple stressors impact in these operations can cause significant losses of honey
bee colonies.
- Environmental chemicals causing the immuno-suppression of bees and triggering CCD
Amongst other, the neonicotinoids, a class of pesticides that have been ext ensively adopted for pest
management. Although highly effective in controlling insect pests; these chemicals are known to be
highly toxic to honey bees and other pollinators.
Latest findings
A comparison of healthy and unhealthy bee colonies points to a virus contributing to Colony Collapse
Disorder (CCD), according to a report being published by the journal Science, at the Science Express web site, on
06 September 200735.
A team led by scientists from the Columbia University Mailman School of Public Health, Pennsylvania State
University, the USDA Agricultural Research Service, University of Arizona, and 454 Life Sciences has found a
significant connection between the Israeli Acute Paralysis Virus (IAPV) and colony collapse disorder (CCD) in
honey bees. The findings, an important step in addressing the disorder that has been decimating bee colonies
across the United States.
3. Factors contributing to the decline
3.1. Habitat fragmentation, loss and degradation
- Degradation and fragmentation as the main adverse habitat changes for pollinator populations36.
- Hedgerows, field margins, embankments, and other "waste places" provide nesting habitat for some native
bees. Removal of these often unappreciated habitats has been associated with dramatic declines in
Germany’s native bee fauna since the 1960s37.
- Fragmentation and habitat destruction can add to the rate of genetic erosion by reducing gene flow
between demes (locally interbreeding group within a geographic population), and increases the likelihood
that populations and species will become extinct38.
- When large habitats are fragmented into small isolated patches, it is not long before some of the animal
residents decline in numbers to the point that they no longer provide effective ecological services
32 Tautz J, Maier S, Groh C, Rossler W, Brockmann A (2003) Behavioral performance in adult honey bees is infl uenced by the temperature experienced during their larval
development. Proc Nat Acad Sci U S A 100: 7343–7347.
33 Jones J, Helliwell P, Beekman M, Maleszka RJ, Oldroyd BP (2005) The effects of rearing temperature on developmental stability and learning and memory in the honey bee,
Apis mellifera. J Comp Physiol A 191: 1121–1129.
34 Testimony of Diana Cox-Foster at the U.S. House of Representatives Committee on Agriculture
Subcommittee on Horticulture and Organic Agriculture on Colony Collapse Disorder in Honey Bee Colonies in the United States March 29, 2007,
http://www.ento.psu.edu/MAAREC/CCDPpt/CoxFosterTestimonyFinal.pdf
35 Diana L. Cox-Foster et al., "A Metagenomic Survey of Microbes in Honey Bee Colony Co llapse Disorder," ScienceExpress (6 September 20 07): 1-7 (1 0.11 26/science.114 6498(
(su b. req.)
36 Thomas J. A., Telfer M. G. et al, 2004. “Comparative Losses of British Butterflies, Birds, and Plants and the Global Extinction Crisis”. Science: Vol. 303. no. 5665, pp. 1879
1881
37 Westrich, P., 1989. “Die Wildbienen Baden-Württembergs. Allgemeiner Teil: Lebensräume, Verhalten, Ökologie und Schutz”. Verlag Eugen Ulmer, Stuttgart, Germany.
38 Barrett, S. C. H., and J. R. Kohn. 1991. “Genetic and evolutionary consequences of small population size in plants: implications for conservation”. Pages 1-30 in D. A. Falk and
K. E. Holsinger, editors. Genetics and conservation of rare plants. Oxford University Press, New York, New York, USA.
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beneficial to plants39. Because some wild pollinators need undisturbed habitat for nesting, roosting and
foraging, they are very susceptible to habitat degradation and fragmentation.
- Urbanisation not only removes habitat directly but also isolates and fragments much of the land that it
does not degrade or assimilate.
- Reduction of food sources.
- Fewer sites for mating, nesting and migration.
- (over)grazing and early cutting of hay meadows results in plants not reaching the flowering stage.
However, forest clearing has opened up previously shaded, humid habitats for many sun-loving pollinators
and their plants40. Roadsides, with their partially compacted soils, are frequently favoured nesting sites for
bees and wasps.
3.2. Agriculture practices
Improper use of pesticides, herbicides and insecticides, for example coating seeds with regular or systemic
insecticide (such as Imidacloprid), which is absorbed by the root and migrates through every part of the plant
including pollen and nectar, poses a potential threat for pollinators such as honeybees and other insects. A study
by Bonmatin et al.41 revealed that pesticides, including the ones mentioned above, cause bees to lose their sense of
direction. This is the goal for insects harmful to the crops, but should be avoided for useful pollinators. In fact
other studies revealed the high toxicity of Imidacloprid and associated inert ingredients for cats, fish, rats, rabbits,
birds and earthworms42.
The replacement of natural plant communities by monoculture, is also a factor since most monoculture are
not capable of sustaining pollinator populations: wheat and corn do not provide nectar or pollen needs for any bee
species43. Adding to this, insecticides are applied not only on agricultural fields but also in backyards, recreational
areas, forests and mosquito-ridden marshes and swamps. The broad-spectrum insecticides that are commonly used
are oft en as toxic to beneficial insects as they are to the target species44.
Whether managed or wild, pollinators need protection from excessive exposure to pesticides and other
chemicals that can poison them or impair their reproduction. These chemicals can also eliminate nectar sources for
pollinators, destroy larval host plants for moths and butterflies, and deplete nesting materials for bees45. On the
other hand, it may be that plant losses from chronic herbicide use are, in fact, driving losses of pollinator species,
and not vice versa46
3.3. Other factors
- Diseases. Honey bees have been affected by Varroa mites, which is a virus transmitter, in hives, due to
appearance of resistance to acaricides.
- For genetic reasons, bees are more extinction prone than other taxa because single-locus sex
determination makes them particularly sensitive to the effects of small population size through the
production of sterile diploid males .
39 Hendrix, S.D., 1994, “Effects of population size on fertilzation, seed production, and seed predation in two prairie legumes”. North American Prairie Conference Proceedings
13: 115-119.
Bohart, G. E. 1972, Management of habitats for wild bees. Proceed ings of the Tall Timbers Conference on Ecological Animal Control by Habitat Management 3: 253-266
41 Bonmatin, J.M., P.A. Marchand, R. Charvet, M.E. Colin, (1994): Fate of systemic insecticides in fields (Imidacloprid and Fipronil) and risks
for pollinators, in First European Conference of Apidology, Udine 19-23 September 2004.
42 Cox, C., (2001), Imidacloprid, Insecticide factsheet, journal of Pesticide Reform, Vol. 21, N°1, http://www.pesticide.org/imidacloprid.pdf.
43 Cane, J. H. and V. J. Tepedino. 2001. “Causes and extent of declines among native North American invertebrate pollinators: detection, evidence, and consequences”.
Conservation Ecology 5(1): 1. [online] URL: www.consecol.org/vol5/iss1/art1
44 Johansen, C. A., and D. F. Mayer. 1990. “Pollinator protection: a bee and pesticide handbook”. Wicwas Press, Cheshire, Connecticut, USA.
45 Nabhan, G.P. and S.L. Buchmann, 1996 (in press), Pollination services: biodiversity's direct link to world food stability, in G. Daly, ed. Ecosystem Services, Island Press,
Washington, D.C.
46 Cane, J. H. and V. J. Tepedino. 2001. “Causes and extent of declines among native North American invertebrate pollinators: detection, evidence, and consequences”.
Conservation Ecology 5(1): 1. [online] URL: www.consecol.org/vol5/iss1/art1
47 Zayed, A. and Packer, L. (2005) Complementary sex determination substantially increases extinction proneness of haplodiploid populations. Proc. Natl. Acad. Sci. U. S. A. 102,
10742–10746
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- Competition from invasive non-native species.
- Predators.
- Global and local climate change. Land-cover changes affect regional climates through changes in surface
energy and water balance.
- Decrease in larval host plants.
- (Elimination of subsidies for beekeepers)
4. Consequences of decline
- Less frequent flower visit ation, abrupt or gradual decrease of seed and fruit production.
- Beekeeping sector in danger in several areas in Europe.
- Self-compatible flower plants can suffer from inbreeding.
- Pistil senescence.
5. International Conventions / Relevant Policy Measures / Recommendations
5.1. Larval stage conservation
Important invertebrate pollinators have discrete larval stages whose mobility and habitat requirements are
dramatically different from those of the winged adult. Conservation initiatives have sometimes been slow to
consider the needs of different life-cycle stages. For example, many conservation-minded researchers advocate
planting nectar plants for butterflies, but then fail to foster their larval host plants
48.
5.2. Alternative agricultural
Alternative agricultural techniques can provide non-toxic methods of weed and insect control that
incorporate use of habitat set-asides for beneficial insect populations and require t he use of fewer toxins.
Gardeners and farmers can rely on alternative non-toxic methods to control pests and weeds. More widespread
practice of such methods has the potential to reduce wildlife exposure to insecticides, herbicides and fungicides49.
Farmers that set aside land to support wild pollinators could be rewarded for such a practice. Unploughed
farmland set aside for several years can produce vegetation that supports considerable insect diversity and benefits
nearby crops by providing pollinators and other beneficial insect s. Large-scale protection and management of
habitat networks are required to minimize habitat-related declines and to maximize the ability of species to track
the distribution of suitable climate50.
A major objective will be to identify, test and document good agricultural practices for pollinator
conservation and management, through an "ecosystem approach". Farmers might be encouraged to protect
"corridors" that connect natural habitats, or uncultivated areas within and around cultivated ones (see also
“Pollinator Friendly Practices” from NAPPC.org).
6. Conclusions
Anthropogenic activities may be detrimental to some species but beneficial to others, with sometimes subtle
and counter intuitive causal linkages51, 52. It is essential to recognize that pollination is not a free service, and
that investment and stewardship are required to protect and sustain it. Economic assessments of agricultural
productivity should account for the "cost" of sustaining wild and managed pollinator populations53. There is a
need for Well-documented cases of specific pollinator declines notwithstanding, rapid extrapolation from our
48 Cane, J. H. and V. J. Tepedino. 2001. “Causes and extent of declines among native North American invertebrate pollinators: detection, evidence, and consequences”.
Conservation Ecology 5(1): 1. [online] URL: www.consecol.org/vol5/iss1/art1
49 Co rbet, S.A., 1995. “Insects, plants and succession: adv antages of long-term set-asid e”. Agriculture Ecosystems & Env ironment 53:201-217.
50 Warren M. S., Hill J. K et al, 2001. “Rapid responses of British butterflies to opposing forces of climate and habitat change”. Nature, Volu me 414, Iss ue 6859, pp . 65-6 9.
51 Thomas, C. D., and T. M. Jones. 1993. “Partial recovery of a skipper butterfly (Hesperia comma) from population refuges: lessons for conservation in a fragmented landscape”.
Journal of Animal Ecology 62: 472-481.
52 Benedek, P. 1996. “Structure and density of lucerne pollinating wild bee populations as affected by changing agriculture”. Act a Horticulturae 437: 35 3-35 7.
53 Ingram M. , Nabhan G. and Stephen Buchmann. “Global Pesticide Campaigner”, Volume 6, Number 4, December 1996.
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current knowledge to imply worldwide pollinator and crop production crises might be inappropriate and pre-
mature, much uncertainty remains regarding pollinator-pollination declines54. As Albert Einstein put it bluntly,
No bees, no food for mankind. The bee is the basis for life on this earth.
54 Ghazoul, J., 2005. “Buzziness as usual? Questioning the global pollination crisis”. TRENDS in Ecology and Evolution Vol.20 No.7 July 2005.
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7. References
1. Wilson E.O, 1999. “The Diversity of Life” (new edition). W.W. Norton & Company, Inc. New-York.
2. Wilcove, D.S., D. Rothstein, J. Dubow, A. Phillips, and E. Losos. 1998. Quantifying threats to imperiled species in
the United States. BioScience 48:607-615.
3. Food and Agriculture Organisation of the U.N. at www.fao.org.
4. Williams, I.H., 1996. “Aspects of bee diversity and crop pollination in the European Union”. In The Conservation of
Bees (Metheson, A. et al., eds), pp. 63–80, Academic Press.
5. Ingram M., Nabhan G. and Stephen Buchmann, 1996. Global Pesticide Campaigner”, Volume 6, Number 4,
December 1996.
6. Free, J.B., 1993.Insect Pollination of Crops”, Academic Press
7. Biesmeijer J.C., Roberts S. P. M. et al, 2006. “Parallel Declines in Pollinators and Insect-Pollinated Plants in Britain
and the Netherlands”. Science: Vol. 313. no. 5785, pp. 351 – 354.
8. Thomas J. A., Telfer M. G. et al, 2004. “Comparative Losses of British Butterflies, Birds, and Plants and the Global
Extinction Crisis”. Science: Vol. 303. no. 5665, pp. 1879 – 1881.
9. Warren M. S., Hill J. K et al, 2001. Rapid responses of British butterflies to opposing forces of climate and habitat
change”. Nature, Volume 414, Issue 6859, pp. 65-69.
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URLs:
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Institute) at www.pollinator.org
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i L’Institut National de Recherche Agronomique at www.inra.fr
j Food and Agriculture Organisation of the U.N. at www.fao.org
... Among those models, agroecology has become prominent in the research and policy debate about the sustainability of agriculture [3][4][5]. In Europe, debates around the sustainability of agriculture are becoming increasingly prominent [2,[6][7][8][9][10], and the European Union (EU) recently increased its commitment to sustainable agriculture with the approval of the Green Deal, the Biodiversity Strategy, and the Farm-to-Fork Strategy, while the new Common Agricultural Policy (CAP) reform (2023-2027) establishes ambitious environmental objectives. ...
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This article is aimed at analyzing the potential that CAP 2014–2020-related instruments have on supporting agroecological transitions in Europe by focusing on the strengths and weaknesses of key instruments. Through a stepwise participatory research methodology, 105 key stakeholders (farmers, advisors, academics, environment experts, administration representatives, and professionals from food chains) in 15 countries in Europe were engaged in the discussion of the potential of current CAP instruments to solve the barriers that constrain agroecological farming systems in their particular regions. The results of this comparative study show which CAP instruments are valued with a high potential to support transitions to agroecology. The analysis of the stakeholders’ perceptions contributes to an enhanced understanding of why CAP instruments have failed or succeeded to promote agroecological transitions.
... Our method could be applied effectively to crops grown under controlled environments. Populations of honey bees [62][63][64][65] and other wild bees 66,67 have declined globally in recent years. The importance of maintaining an abundance of wild insect fauna that can serve as crop pollinators is increasingly recognized 5,68,69 , but few studies have examined the effectiveness of wild pollinators at pollinating and fruiting crops 70,71 . ...
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Understanding of pollination systems is an important topic for evolutionary ecology, food production, and biodiversity conservation. However, it is difficult to grasp the whole picture of an individual system, because the activity of pollinators fluctuates depending on the flowering period and time of day. In order to reveal effective pollinator taxa and timing of visitation to the reproductive success of plants under the complex biological interactions and fluctuating abiotic factors, we developed an automatic system to take photographs at 5-s intervals to get near-complete flower visitation by pollinators during the entire flowering period of selected flowers of Nelumbo nucifera and track the reproductive success of the same flowers until fruiting. Bee visits during the early morning hours of 05:00–07:59 on the second day of flowering under optimal temperatures with no rainfall or strong winds contributed strongly to seed set, with possible indirect negative effects by predators of the pollinators. Our results indicate the availability of periodic and consecutive photography system in clarifying the plant-pollinator interaction and its consequence to reproductive success of the plant. Further development is required to build a monitoring system to collect higher-resolution time-lapse images and automatically identify visiting insect species in the natural environment.
... Pollinators and their interactions with plants provide essential ecosystem services for biodiversity and for humanity, and thus recent reports showing declines in the abundance and diversity of pollinators are cause for concern (Kluser et al., 2007;Dalsgaard, 2020). Understanding trends in pollinating insect is more complex than previously thought, which has led to calls for more studies on wild pollinators and their services (Abrol, 2012, pp. ...
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Pollinators play a key role in plant reproduction, which is critical to secure our food supply and to maintain the biodiversity of wild plants. Recent reports on declines in the abundance and diversity of pollinators has resulted in urgent calls for more studies on pollinators and their services, with the goal of halting their decline. This requires better data on plant-pollinator interactions, collected at across broad spatial and temporal grains. Currently, pollination data are acquired from field observations of pollinators contacting reproductive parts of flowers. Pollinators are identified either in the field or in the lab using microscopy. These methods are labor and time intensive and require specialised expertise in insect taxonomy, which prevents data from being collected at the large scales that are needed to address pressing environmental questions. Thus, there is a need to transform the way that data is collected in the field of pollination ecology by developing new techniques that automatically detect and identify insect pollinators from images. The goal of this study is to use state of- the-art deep learning tools for automated monitoring of plantpollinators interactions from field images in Europe. There is a need to develop tools that can more broadly identify several orders of insects with high taxonomic resolution at an accuracy that matches that of human entomologists. The development of an automated method for pollinator identification using the object recognition algorithm YOLOv5 is presented in this thesis. The selection of the images for the training dataset was carefully and precisely performed as the images to train the model are the key driver for the successful identification of insects. Over 17,000 images of eight groups of insects that can be considered flower visitors, were retrieved using the open-source online databases iNaturalist and observation.org. After training the object detection network, a comparison and evaluation of the experimental results obtained using different learning approaches showed that the model can successfully identify the eight insect groups with an average accuracy of 91%. This provides the first steps into a robust deep learning method to simplify the laborious process of manual pollinator classification and contribute to a creation of a pan-European monitoring system for pollinators.
... Pollination is widely recognized as a critical ecosystem service for the majority of economically relevant crops that require an effective pollination system (Klein et al., 2007). Over 75% of the major world crops and 80% of all flowering plant species rely on animal pollinators, mostly species of wild bee and other wildlife (Kluser & Peduzzi, 2007). Currently, the most abundant and most effective pollinator in agriculture is the honeybee (Apis mellifera) (Paudel et al., 2015). ...
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... These tests should provide sound data for plant protection products to be safely applied in the respective crop. Nonetheless, the link between pesticides and effects on pollinators (including honey bees) has been extensively reported (Kluser and Peduzzi, 2007;Vanbergen and Initiative, 2013;Goulson et al., 2015;Potts et al., 2016;Kopec, 2017;Powney et al., 2019), evidencing the need to improve pollinators protection even when exposed to low pesticide doses. In this study, at the sub-lethal dose of sulfoxaflor of 26 ng/bee, forager bees exhibit such high degree of disorientation that cannot reach the colony, leading eventually to their death. ...
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... Pollinator decline is globally a decline in the abundance of insects and other pollinators in various ecosystems that began at the end of the twentieth century, and recent research shows that it is increasingly becoming a threat to agricultural productivity due to improper farm maintenance operations, with uncontrolled use of synthetic pesticides, which harms natural cucumber pollinators (Huang & Giray, 2012;Kluser & Peduzzi, 2007;Okolle, Ngosong, Nanganoa, & Dopgima, 2020). For successful pollination of many cucurbits, around twenty bees must visit each female flower (Inam et al., 2015). ...
... Pollinator decline is globally a decline in the abundance of insects and other pollinators in various ecosystems that began at the end of the twentieth century, and recent research shows that it is increasingly becoming a threat to agricultural productivity due to improper farm maintenance operations, with uncontrolled use of synthetic pesticides, which harms natural cucumber pollinators (Huang & Giray, 2012;Kluser & Peduzzi, 2007;Okolle, Ngosong, Nanganoa, & Dopgima, 2020). For successful pollination of many cucurbits, around twenty bees must visit each female flower (Inam et al., 2015). ...
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... The pollinator population is on a steady decline for decades [KP07]. We still do not understand all underlying mechanisms and influences on the decline of honey bees. ...
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... Chalkbrood is a fungal honey bee brood disease caused by Ascosphaera apis [225,226], a heterothallic parasitic fungus, belonging to the phylum Ascomycota. This disease is currently widespread throughout the world and different studies have pointed out that chalkbrood incidence may be increasing [225,227]. This economically important disease, although it does not destroy the entire colony, weakens it, and can lead to significant losses of both honey bees and colony productivity [228][229][230]. ...
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Imidacloprid binds nicotinic ACh receptors. The vital functions of bees are affected by sublethal levels of imidacloprid from 2 to 20 µg/kg in the feeding source [1]. Chronic mortality (50%) was observed at 0.1 µg/kg [2]. We developed a LC/MS-MS methodology for plants and pollens (LOD = 0.1 µg/kg and LOQ =1 µg/kg) according to GLP and directive 96/23 EC [3]. Our results show that imidacloprid (Gaucho seed dressing) diffuses in sunflowers and maize, with an ascent at the flowering [4]. Here, average levels are 5-8 µg/kg in flowers and 2-3 µg/kg in pollens [5]. The risk is evaluated by the PEC/PNEC ratio. PEC/PNEC, calculated from the consumption of pollen by bees, is then in the range of 20-30 when considering the loss of feeding activity. PEC/PNEC is 700-800 when considering the chronic mortality after 11 days [6]. The ratio further increases when considering also the contamination of nectar (1.9 µg/kg) and our results are consistent with an independent evaluation made by using the exhaustive list of data available [7]. Gaucho on sunflower has been suspended in France since1999. A new evaluation for maize is in progress.
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Biologists are nearly unanimous in their belief that humanity is in the process of extirpating a significant portion of the earth's spe­ cies. The ways in which we are doing so reflect the magnitude and scale of human enterprise. Everything from highway construction to cattle ranch­ ing to leaky bait buckets has been implicated in the demise or endan­ germent of particular species. Ac­ cording to Wilson (1992), most of these activities fall into four major categories, which he terms "the mind­ less horsemen of the environmental apocalypse": overexploitation, habi­ tat destruction, the introduction of non-native (alien) species, and the spread of diseases carried by alien species. To these categories may be added a fifth, pollution, although it can also be considered a form of habitat destruction. Surprisingly, there have been reIa­ tively few analyses of the extent to which each of these factors-much less the more specific deeds encomDavid S. Wilcove is a senior ecologist at the Environmental Defense Fund, Wash­ ington, DC 20009. David Rothstein re­ ceived his J.D. in 1997 from Northeastern
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1. In Britain, Hesperia comma inhabits heavily grazed calcareous grasslands. When rabbits were killed by myxomatosis in the mid-1950s, this habitat became overgrown and H. comma declined to 46 or fewer localities in 10 refuge regions (Thomas et al. 1986). By 1982, rabbits had recovered and many former sites again appeared suitable, but had not been recolonized. 2. Between 1982 and 1991, the number of habitat patches that were populated increased by 30% in the South and North Downs. Most of the increase was in East Sussex. 3. The probability of colonization between 1982 and 1991 increased with patch area, and declined with isolation from source populations (maximum 8-65 km). The probability of local extinction declined with increasing patch area, and increased with isolation. Thus, habitat patches were most likely to be occupied by H. comma if they were relatively large and close to other populated patches. 4. Many patches of suitable habitat had still not been recolonized by 1991. If the habitat was not fragmented, H. comma could be expected to recover its status in South East England in 50-75 years. But, applying logistic equations for colonization and extinction to the real, fragmented landscape, we predict little or no further spread in 100 years, except in East Sussex. In most areas, zones (> 10 km wide) of unsuitable habitat are expected to prevent continued spread. 5. The dynamics of H. comma over 100 years demonstrate (i) the importance of environmental events that are correlated over large areas, (ii) the importance of refuges during adverse periods, and (iii) the potential for alternative, stable regional distributions, depending on the locations of refuges and barriers to dispersal. 6. Conservation of H. comma requires the protection of metapopulations in networks of habitat patches.