Editing Mosquito (section)

=== Finding hosts ===

[[File:How to attract mosquitoes.svg|thumb|upright=1.5|Blood-feeding female mosquitoes find their hosts using multiple cues, including exhaled [[carbon dioxide]], heat, and many different [[odorant]]s.]]

Most mosquito species are [[crepuscular]], feeding at dawn or dusk, and resting in a cool place through the heat of the day.<ref>{{cite conference |conference=Proceedings of the Eighty-Second Annual Meeting of the New Jersey Mosquito Control Association |year=1989 |pages=53–57 |last=Crans |first=Wayne J. |url=http://www.rci.rutgers.edu/~insects/restbox.htm |title=Resting boxes as mosquito surveillance tools |url-status=dead |archive-url=https://web.archive.org/web/20060720195034/http://www.rci.rutgers.edu/~insects/restbox.htm |archive-date=2006-07-20 }}</ref> Some species, such as the [[Asian tiger mosquito]], are known to fly and feed during daytime.<ref>{{cite web |last1=Maruniak |first1=James E. |title=Asian tiger mosquito |url=http://entnemdept.ufl.edu/creatures/aquatic/asian_tiger.htm |website=Featured Creatures |publisher=[[University of Florida]] |access-date=October 2, 2014 |location=[[Gainesville, Florida]] |date=July 2014 |archive-date=September 7, 2014 |archive-url=https://web.archive.org/web/20140907181247/http://entnemdept.ufl.edu/creatures/aquatic/asian_tiger.htm |url-status=live }}</ref> Female mosquitoes hunt for hosts by smelling substances such as [[carbon dioxide]] (CO<sub>2</sub>) and [[1-Octen-3-ol|1-octen-3-ol]] (mushroom alcohol, found in exhaled breath) produced from the host, and through visual recognition.<ref>{{cite journal |last1=Hallem |first1=Elissa A. |last2=Nicole Fox |first2=A. |last3=Zwiebel |first3=Laurence J. |last4=Carlson |first4=John R. |title=Olfaction: mosquito receptor for human-sweat odorant |journal=Nature |volume=427 |issue=6971 |pages=212–213 |date=January 2004 |pmid=14724626 |doi=10.1038/427212a |bibcode=2004Natur.427..212H |s2cid=4419658 }}</ref> The [[semiochemical]] that most strongly attracts ''[[Culex]] quinquefasciatus'' is [[nonanal]].<ref>{{cite magazine |url=https://www.usnews.com/science/articles/2009/10/28/scientists-identify-key-smell-that-attracts-mosquitoes-to-humans.html |title=Scientists identify key smell that attracts mosquitoes to humans |magazine=[[US News]] |date=October 28, 2009 |access-date=5 September 2017 |archive-date=10 September 2024 |archive-url=https://web.archive.org/web/20240910225722/https://www.usnews.com/science/articles/2009/10/28/scientists-identify-key-smell-that-attracts-mosquitoes-to-humans |url-status=live }}</ref> Another attractant is [[sulcatone]].<ref>{{cite news |url=https://richarddawkins.net/2014/11/scientists-have-identified-the-gene-that-makes-mosquitoes-crave-human-blood/ |title=Scientists have identified the gene that makes mosquitoes crave human blood |publisher=[[Richard Dawkins Foundation]] |date=November 21, 2014 |access-date=November 21, 2014 |archive-date=November 25, 2014 |archive-url=https://web.archive.org/web/20141125134812/https://richarddawkins.net/2014/11/scientists-have-identified-the-gene-that-makes-mosquitoes-crave-human-blood/ |url-status=live }}</ref> A large part of the mosquito's sense of smell, or olfactory system, is devoted to sniffing out blood sources. Of 72 types of odor receptors on its antennae, at least 27 are tuned to detect chemicals found in perspiration.<ref>{{cite news |url=http://www.timesonline.co.uk/tol/news/science/medicine/article7014046.ece |newspaper=The Times |location=London |title=Sweat and blood why mosquitoes pick and choose between humans |first=Hannah |last=Devlin |date=February 4, 2010 |access-date=May 13, 2010 |archive-date=October 3, 2022 |archive-url=https://web.archive.org/web/20221003061323/https://www.thetimes.co.uk/ |url-status=dead }}</ref> In ''Aedes'', the search for a host takes place in two phases. First, the mosquito flies about until it detects a host's odorants; then it flies towards them, using the concentration of odorants as its guide.<ref name="Estrada">{{cite book |last1=Estrada-Franco |first1=R. G. |last2=Craig |first2=G. B. |year=1995 |title=Biology, disease relationship and control of ''Aedes albopictus'' |publisher=[[Pan American Health Organization]] |location=Washington, D.C. |series=Technical Paper No. 42}}</ref> Mosquitoes prefer to feed on people with [[type O blood]], an abundance of skin bacteria, high body heat, and pregnant women.<ref>{{cite journal |last1=Shirai |first1=Yoshikazu |last2=Funada |first2=Hisashi |last3=Takizawa |first3=Hisao |last4=Seki |first4=Taisuke |last5=Morohashi |first5=Masaaki |last6=Kamimura |first6=Kiyoshi |title=Landing preference of ''Aedes albopictus'' (Diptera: Culicidae) on human skin among ABO blood groups, secretors or nonsecretors, and ABH antigens |journal=Journal of Medical Entomology |volume=41 |issue=4 |pages=796–799 |date=July 2004 |pmid=15311477 |doi=10.1603/0022-2585-41.4.796 |doi-access=free }}</ref><ref name="Chappell, NPR 2013.07.12: Mosquitos' perceptions of humans">{{cite news |last1=Chappell |first1=Bill |title=5 Stars: A Mosquito's Idea Of A Delicious Human |url=https://www.npr.org/blogs/thetwo-way/2013/07/12/201521175/5-stars-a-mosquitos-idea-of-a-delicious-human |access-date=23 July 2021 |publisher=[[NPR]] |date=12 July 2013 |archive-date=14 October 2014 |archive-url=https://web.archive.org/web/20141014202549/http://www.npr.org/blogs/thetwo-way/2013/07/12/201521175/5-stars-a-mosquitos-idea-of-a-delicious-human |url-status=live }}</ref> Individuals' attractiveness to mosquitoes has a [[heritable]], genetically controlled component.<ref>{{cite journal  |last1=Fernández-Grandon |first1=G. Mandela |last2=Gezan |first2=Salvador A. |last3=Armour |first3=John A. L. |last4=Pickett |first4=John A. |last5=Logan |first5=James G. |title=Heritability of attractiveness to mosquitoes |journal=PLOS ONE |volume=10 |issue=4 |pages=e0122716 |date=22 April 2015 |pmid=25901606 |pmc=4406498 |doi=10.1371/journal.pone.0122716 |bibcode=2015PLoSO..1022716F |doi-access=free }}</ref>

The multitude of characteristics in a host observed by the mosquito allows it to select a host to feed on. This occurs when a mosquito notes the presence of CO<sub>2</sub>, as it then activates odour and visual search behaviours that it otherwise would not use. In terms of a mosquito’s olfactory system, chemical analysis has revealed that people who are highly attractive to mosquitoes produce significantly more [[carboxylic acid]]s.<ref>{{Cite journal |last1=De Obaldia |first1=Maria Elena |last2=Morita |first2=Takeshi |last3=Dedmon |first3=Laura C. |last4=Boehmler |first4=Daniel J. |last5=Jiang |first5=Caroline S. |last6=Zeledon |first6=Emely V. |last7=Cross |first7=Justin R. |last8=Vosshall |first8=Leslie B. |display-authors=3 |date=2022-10-27 |title=Differential mosquito attraction to humans is associated with skin-derived carboxylic acid levels |journal=Cell |volume=185 |issue=22 |pages=4099–4116.e13 |doi=10.1016/j.cell.2022.09.034 |pmid=36261039|pmc=10069481 }}</ref> A human's unique body odour indicates that the target is actually a human host rather than some other living warm-blooded animal (as the presence of CO<sub>2</sub> shows). Body odour, composed of [[volatile organic compound]]s emitted from the skin of humans, is the most important cue used by mosquitoes.<ref>{{Cite journal |last=McBride |first=Carolyn |date=12 November 2014 |title=Evolution of mosquito preference for humans linked to an odorant receptor |journal=Nature|volume=515 |issue=7526 |pages=222–227 |doi=10.1038/nature13964 |pmid=25391959 |pmc=4286346 |bibcode=2014Natur.515..222M }}</ref> Variation in skin odour is caused by body weight, hormones, genetic factors, and metabolic or genetic disorders. Infections such as malaria can influence an individual’s body odour. People infected by malaria produce relatively large amounts of ''Plasmodium''-induced aldehydes in the skin, creating large cues for mosquitoes as it increases the attractiveness of an odour blend, imitating a "healthy" human odour. Infected individuals produce larger amounts of aldehydes [[heptanal]], [[octanal]], and [[nonanal]]. These compounds are detected by mosquito antennae. Thus, people infected with malaria are more prone to mosquito biting.<ref>{{Cite journal |last1=Robinson |first1=Ailie |last2=Busula |first2=Annette O. |last3=Voets |first3=Mirjam A. |last4=Beshir |first4=Khalid B. |last5=Caulfield |first5=John C. |last6=Powers |first6=Stephen J. |last7=Verhulst |first7=Niels O. |last8=Winskill |first8=Peter |last9=Muwanguzi |first9=Julian |last10=Birkett |first10=Michael A. |last11=Smallegange |first11=Renate C. |last12=Masiga |first12=Daniel K. |last13=Mukabana |first13=W. Richard |last14=Sauerwein |first14=Robert W. |last15=Sutherland |first15=Colin J. |display-authors=3 |date=May 2018 |title=Plasmodium -associated changes in human odor attract mosquitoes |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=115 |issue=18 |pages=E4209–E4218 |doi=10.1073/pnas.1721610115 |doi-access=free |pmc=5939094 |pmid=29666273 |bibcode=2018PNAS..115E4209R }}</ref>

Contributing to a mosquito's ability to activate search behaviours, a mosquito's visual search system includes sensitivity to wavelengths from different colours. Mosquitoes are attracted to longer wavelengths, correlated to the colours of red and orange as seen by humans, and range through the spectrum of human skin tones. In addition, they have a strong attraction to dark, high-contrast objects, because of how longer wavelengths are perceived against a lighter-coloured background.<ref name="ReferenceA">{{Cite journal |last1=Alonso San Alberto |first1=Diego |last2=Rusch |first2=Claire |last3=Zhan |first3=Yinpeng |last4=Straw |first4=Andrew D. |last5=Montell |first5=Craig |last6=Riffell |first6=Jeffrey A. |date=2022-02-04 |title=The olfactory gating of visual preferences to human skin and visible spectra in mosquitoes |journal=[[Nature Communications]] |volume=13 |issue=1 |pages=555 |doi=10.1038/s41467-022-28195-x |pmid=35121739 |pmc=8816903 |bibcode=2022NatCo..13..555A}}</ref>
[[File:Culex mosquito proboscis.jpg|thumb|Scanning electron microscope image of the Labium tip of Culex mosquito]]
Different species of mosquitoes have evolved different methods of identifying target hosts. Study of a domestic form and an animal-biting form of the mosquito ''Aedes aegypti'' showed that the evolution of preference for human odour is linked to increases in the expression of the [[olfactory receptor]] AaegOr4. This recognises a compound present at high levels in human odour called [[sulcatone]]. However, the malaria mosquito ''Anopheles gambiae'' also has OR4 genes strongly activated by sulcatone, yet none of them are closely related to AaegOr4, suggesting that the two species have evolved to specialise in biting humans independently.<ref name="ReferenceA"/>