Editing Pollinator decline (section)

{{Short description|Reduction in abundance of insect and other animal pollinators}}
[[File:A_Dead_carpenter_bee_(Xylocopa_pubescens).jpg|thumb|A dead carpenter bee]]

'''Pollinator decline''' is the reduction in abundance of [[insect]] and other animal [[pollinator]]s in many [[ecosystem]]s worldwide that began being recorded at the end of the 20th century. Multiple lines of evidence exist for the reduction of wild pollinator populations at the regional level, especially within Europe and North America.<ref name="Widespread losses of pollinating in">{{cite journal |last1=Powney |first1=Gary D. |last2=Carvell |first2=Claire |last3=Edwards |first3=Mike |last4=Morris |first4=Roger K. A. |last5=Roy |first5=Helen E. |last6=Woodcock |first6=Ben A. |last7=Isaac |first7=Nick J. B. |title=Widespread losses of pollinating insects in Britain |journal=Nature Communications |date=26 March 2019 |volume=10 |issue=1 |pages=1018 |doi=10.1038/s41467-019-08974-9|pmid=30914632 |pmc=6435717 |bibcode=2019NatCo..10.1018P |s2cid=85528078 |doi-access=free }}</ref><ref>{{cite journal |last1=Soroye |first1=Peter |last2=Newbold |first2=Tim |last3=Kerr |first3=Jeremy |title=Climate change contributes to widespread declines among bumble bees across continents |journal=Science |date=7 February 2020 |volume=367 |issue=6478 |pages=685–688 |doi=10.1126/science.aax8591|pmid=32029628 |bibcode=2020Sci...367..685S |s2cid=211049610 |url=https://discovery.ucl.ac.uk/id/eprint/10091324/ |doi-access=free }}</ref><ref>{{cite journal |last1=Goulson |first1=D. |last2=Nicholls |first2=E. |last3=Botias |first3=C. |last4=Rotheray |first4=E. L. |title=Bee declines driven by combined stress from parasites, pesticides, and lack of flowers |journal=Science |date=27 March 2015 |volume=347 |issue=6229 |pages=1255957 |doi=10.1126/science.1255957|pmid=25721506 |s2cid=206558985 |doi-access=free }}</ref><ref>{{cite journal |last1=Potts |first1=Simon G. |last2=Biesmeijer |first2=Jacobus C. |last3=Kremen |first3=Claire |last4=Neumann |first4=Peter |last5=Schweiger |first5=Oliver |last6=Kunin |first6=William E. |title=Global pollinator declines: trends, impacts and drivers |journal=Trends in Ecology & Evolution |date=June 2010 |volume=25 |issue=6 |pages=345–353 |doi=10.1016/j.tree.2010.01.007|pmid=20188434 |bibcode=2010TEcoE..25..345P }}</ref> Similar findings from studies in South America, China and Japan make it reasonable to suggest that declines are occurring around the globe.<ref>{{cite journal |last1=Schmid-Hempel |first1=Regula |last2=Eckhardt |first2=Michael |last3=Goulson |first3=David |last4=Heinzmann |first4=Daniel |last5=Lange |first5=Carlos |last6=Plischuk |first6=Santiago |last7=Escudero |first7=Luisa R. |last8=Salathé |first8=Rahel |last9=Scriven |first9=Jessica J. |last10=Schmid-Hempel |first10=Paul |title=The invasion of southern South America by imported bumblebees and associated parasites |journal=Journal of Animal Ecology |date=July 2014 |volume=83 |issue=4 |pages=823–837 |doi=10.1111/1365-2656.12185|pmid=24256429 |doi-access=free |bibcode=2014JAnEc..83..823S }}</ref><ref>{{cite journal |last1=Xie |first1=Zhenghua |last2=Williams |first2=Paul H. |last3=Tang |first3=Ya |title=The effect of grazing on bumblebees in the high rangelands of the eastern Tibetan Plateau of Sichuan |journal=Journal of Insect Conservation |date=1 December 2008 |volume=12 |issue=6 |pages=695–703 |doi=10.1007/s10841-008-9180-3|bibcode=2008JICon..12..695X |s2cid=19979709 }}</ref><ref>{{cite journal |last1=Williams |first1=Paul |last2=Tang |first2=Ya |last3=Yao |first3=Jian |last4=Cameron |first4=Sydney |title=The bumblebees of Sichuan (Hymenoptera: Apidae, Bombini) |journal=Systematics and Biodiversity |date=1 June 2009 |volume=7 |issue=2 |pages=101–189 |doi=10.1017/S1477200008002843|bibcode=2009SyBio...7..101W |s2cid=86166557 }}</ref><ref>{{cite journal |last1=Inoue |first1=Maki N. |last2=Yokoyama |first2=Jun |last3=Washitani |first3=Izumi |title=Displacement of Japanese native bumblebees by the recently introduced Bombus terrestris (L.) (Hymenoptera: Apidae) |journal=Journal of Insect Conservation |date=1 April 2008 |volume=12 |issue=2 |pages=135–146 |doi=10.1007/s10841-007-9071-z|bibcode=2008JICon..12..135I |s2cid=33992235 }}</ref> The majority of studies focus on bees, particularly [[honeybee]] and [[bumblebee]] species, with a smaller number involving hoverflies and lepidopterans.<ref>{{cite journal |last1=Biesmeijer |first1=J. C. |title=Parallel Declines in Pollinators and Insect-Pollinated Plants in Britain and the Netherlands |journal=Science |date=21 July 2006 |volume=313 |issue=5785 |pages=351–354 |doi=10.1126/science.1127863|pmid=16857940 |bibcode=2006Sci...313..351B |s2cid=16273738 }}</ref><ref name="Widespread losses of pollinating in"/><ref>{{cite journal |last1=Fox |first1=Richard |last2=Oliver |first2=Tom H. |last3=Harrower |first3=Colin |last4=Parsons |first4=Mark S. |last5=Thomas |first5=Chris D. |last6=Roy |first6=David B. |title=Long-term changes to the frequency of occurrence of British moths are consistent with opposing and synergistic effects of climate and land-use changes |journal=Journal of Applied Ecology |date=August 2014 |volume=51 |issue=4 |pages=949–957 |doi=10.1111/1365-2664.12256|pmid=25954052 |pmc=4413814 |bibcode=2014JApEc..51..949F }}</ref><ref>{{cite journal |last1=Forister |first1=Matthew L. |last2=Jahner |first2=Joshua P. |last3=Casner |first3=Kayce L. |last4=Wilson |first4=Joseph S. |last5=Shapiro |first5=Arthur M. |title=The race is not to the swift: Long-term data reveal pervasive declines in California's low-elevation butterfly fauna |journal=Ecology |date=2011 |volume=92 |issue=12 |pages=2222–2235 |doi=10.1890/11-0382.1|pmid=22352162 |bibcode=2011Ecol...92.2222F }}</ref><ref>{{cite journal |last1=Semmens |first1=Brice X. |last2=Semmens |first2=Darius J. |last3=Thogmartin |first3=Wayne E. |last4=Wiederholt |first4=Ruscena |last5=López-Hoffman |first5=Laura |last6=Diffendorfer |first6=Jay E. |last7=Pleasants |first7=John M. |last8=Oberhauser |first8=Karen S. |last9=Taylor |first9=Orley R. |title=Quasi-extinction risk and population targets for the Eastern, migratory population of monarch butterflies (Danaus plexippus) |journal=Scientific Reports |pages=23265 |language=en |doi=10.1038/srep23265 |date=September 2016|volume=6 |pmid=26997124 |pmc=4800428 |bibcode=2016NatSR...623265S }}</ref>

The picture for domesticated pollinator species is less clear. Although the number of managed honey bee colonies in Europe and North America declined by 25% and 59% between 1985-2005 and 1947-2005 respectively, overall global stocks increased due to major hive number increases in countries such as China and Argentina.<ref>{{cite journal |last1=Potts |first1=Simon G. |last2=Roberts |first2=Stuart P. M. |last3=Dean |first3=Robin |last4=Marris |first4=Gay |last5=Brown |first5=Mike A. |last6=Jones |first6=Richard |last7=Neumann |first7=Peter |last8=Settele |first8=Josef |title=Declines of managed honey bees and beekeepers in Europe |journal=Journal of Apicultural Research |date=1 January 2010 |volume=49 |issue=1 |pages=15–22 |doi=10.3896/IBRA.1.49.1.02|bibcode=2010JApiR..49...15P |s2cid=67794397 }}</ref><ref>{{cite journal |last1=vanEngelsdorp |first1=Dennis |last2=Hayes |first2=Jerry Jr. |last3=Underwood |first3=Robyn M. |last4=Pettis |first4=Jeffery |title=A Survey of Honey Bee Colony Losses in the U.S., Fall 2007 to Spring 2008 |journal=PLOS ONE |date=30 December 2008 |volume=3 |issue=12 |pages=e4071 |doi=10.1371/journal.pone.0004071|pmid=19115015 |pmc=2606032 |bibcode=2008PLoSO...3.4071V |doi-access=free }}</ref><ref name="The Global Stock of Domesticated Ho">{{cite journal |last1=Aizen |first1=Marcelo A. |last2=Harder |first2=Lawrence D. |title=The Global Stock of Domesticated Honey Bees Is Growing Slower Than Agricultural Demand for Pollination |journal=Current Biology |date=June 2009 |volume=19 |issue=11 |pages=915–918 |doi=10.1016/j.cub.2009.03.071|pmid=19427214 |s2cid=12353259 |doi-access=free |bibcode=2009CBio...19..915A }}</ref> Nevertheless, in the time managed honeybee hives increased by 45% demand for animal pollinated crops tripled, highlighting the danger of relying on domesticated populations for pollination services.<ref name="The Global Stock of Domesticated Ho"/>

Pollinators participate in the sexual reproduction of many plants by ensuring [[cross-pollination]], essential for some species and a major factor in ensuring [[genetic diversity]] for others. Since plants are the primary food source for animals, the possible reduction or disappearance of pollinators has been referred to as an "armageddon" by some journalists.