Editing Pollinator decline (section)

== Possible explanations ==
Although the existence of pollinator decline can be difficult to determine, a number of possible reasons for the theoretical concept have been proposed, such as exposure to pathogens, parasites, and pesticides; [[habitat destruction]]; [[climate change]]; market forces; intra- and interspecific competition with native and [[invasive species]]; and genetic alterations.<ref name=3Causes>{{Cite book|url=https://www.nap.edu/read/11761/chapter/5|title=3 Causes of Pollinator Declines and Potential Threats {{!}} Status of Pollinators in North America {{!}} The National Academies Press|language=en|doi=10.17226/11761|year=2007|isbn=978-0-309-10289-6|last1=Council|first1=National Research|last2=Studies|first2=Division on Earth Life|last3=Resources|first3=Board on Agriculture Natural|last4=Sciences|first4=Board on Life|last5=America|first5=Committee on the Status of Pollinators in North | quote=It is difficult to determine whether North American pollinator species are declining, and no less challenging is determining the causes of putative declines or local extirpations. Many explanations have been invoked to account for declines in pollinator populations in North America, including, among others, exposure to pathogens, parasites, and pesticides; habitat fragmentation and loss; climate change; market forces; intra- and inter-specific competition with native and invasive species; and genetic alterations. Careful evaluation of the literature allows some causes to be assigned, but explanations are ambiguous or elusive for other species losses. ... The best evidence of specific pollinator decline is seen in the western honey bee, ''Apis mellifera L.'', the primary commercial pollinator of agricultural crops in North America and the most widely used, actively managed pollinator in the world. The population losses among honey bees are elucidated in a large body of literature...}}</ref><ref name="Rhodes 2018 pp. 121–160"/>

Honey bees are an invasive species throughout most of the world where they have been introduced, and the constant growth in the amount of these pollinators may possibly cause a decrease in native species.<ref name=Aizen2009/> [[Light pollution]] has been suggested a number of times as a possible reason for the possible decline in flying insects.<ref>{{Cite web|title=Light pollution a reason for insect decline!? |url=https://www.igb-berlin.de/en/news/light-pollution-reason-insect-decline|date=19 June 2018|access-date=2023-02-18|website=www.igb-berlin.de|language=en}}</ref><ref>{{Cite web|title=Nighttime Light Pollution May Be Cause of Insect Population Decline|url=https://www.photonics.com/Articles/Nighttime_Light_Pollution_May_Be_Cause_of_Insect/a63612|date=September 2018|access-date=2023-02-18|website=www.photonics.com}}</ref><ref>[https://dspace.library.uu.nl/handle/1874/319074 Insects, bats and artificial light at night: Measures to reduce the negative effects of light pollution] {{Webarchive|url=https://web.archive.org/web/20200220144849/https://dspace.library.uu.nl/handle/1874/319074 |date=2020-02-20 }} in: dspace.library.uu.nl, retrieved 28 July 2018, author: Claudia Rieswijk (2015), Faculty of Science Theses (Master thesis), [[Utrecht university]]</ref><ref>{{cite journal|last1=Longcore |first1=Travis |last2=Rich |first2 = Catherine | year = 2004 | title = Ecological light pollution | journal = Frontiers in Ecology and the Environment | volume = 2 | issue = 4| pages = 191–198 | doi = 10.1890/1540-9295(2004)002[0191:ELP]2.0.CO;2 | doi-access =  }}</ref> One study found that [[air pollution]], such as from cars, has been inhibiting the ability of pollinators such as bees and [[butterfly|butterflies]] to find the fragrances of flowers. Pollutants such as [[ozone]], [[hydroxyl]], and [[nitrate]] [[radical (chemistry)|radical]]s bond quickly with volatile scent molecules of flowers, which consequently travel shorter distances intact. Pollinators must thus travel longer distances to find flowers.<ref>{{cite web|url=http://www.eurekalert.org/pub_releases/2008-04/uov-ffd041008.php|title=Flowers' fragrance diminished by air pollution, University of Virginia study indicates|date=10 April 2008|work=EurekAlert!}}</ref>

Pollinators may also face an increased risk of extinction because of [[global warming]] due to alterations in the seasonal behaviour of species. Climate change can cause bees to emerge at times in the year when flowering plants were not available.<ref name= DailyTelegraph>{{Cite news|date=2014-03-29|title=Bees and the crops they pollinate are at risk from climate change, IPCC report to warn | author = Gosden, Emily| url=http://www.telegraph.co.uk/earth/earthnews/10730667/Bees-and-the-crops-they-pollinate-are-at-risk-from-climate-change-IPCC-report-to-warn.html|access-date=2023-02-18|archive-url=https://web.archive.org/web/20140329151458/http://www.telegraph.co.uk/earth/earthnews/10730667/Bees-and-the-crops-they-pollinate-are-at-risk-from-climate-change-IPCC-report-to-warn.html |archive-date=2014-03-29| periodical = [[The Daily Telegraph]] }}</ref>