Editing Diapause (section)

==Phases of insect diapause==
Diapause in insects is a dynamic process consisting of several distinct phases. While diapause varies considerably from one [[taxon]] of insects to another, these phases can be characterized by particular sets of metabolic processes and responsiveness of the insect to certain environmental stimuli.<ref name="Kostal">{{cite journal |last1= Kostal |first1= V |year= 2006 |title= Eco-physiological phases of insect diapause |journal= Journal of Insect Physiology |volume= 52 |issue= 2|pages= 113–127 |doi=10.1016/j.jinsphys.2005.09.008 |pmid=16332347|bibcode= 2006JInsP..52..113K }}</ref> For example, ''[[Sepsis cynipsea]]'' flies primarily use temperature to determine when to enter diapause.<ref>Blanckenhorn, W. U. (1998). Altitudinal differentiation in the diapause response of two species of dung flies. Ecological Entomology 23, 1-8.</ref> Similarly, ''[[Chrysoperla plorabunda]]'' lacewings regulate their reproductive cycle using daylight length, with adults entering reproductive diapause when there are less than 12-13 hours of daylight.<ref>{{Cite journal |last1=Tauber |first1=Catherine A. |last2=Tauber |first2=Maurice J. |date=June 1987 |title=Inheritance of seasonal cycles in Chrysoperla (Insecta: Neuroptera) |journal=Genetics Research |language=en |volume=49 |issue=3 |pages=215–223 |doi=10.1017/S0016672300027105 |issn=0016-6723|doi-access=free }}</ref> Diapause can occur during any stage of development in arthropods, but each species exhibits diapause in specific phases of development. Reduced oxygen consumption is typical as is reduced movement and feeding.<ref>The Insects; Structure and Function, 4th Edition. R.F. Chapman, Cambridge University Press, 1998. {{ISBN|0-521-57048-4}}, pp. 403–404</ref> In ''[[Polistes exclamans]]'', a social wasp, only the queen is said to be able to undergo diapause.<ref>{{cite journal |last1= Bohm |year= 1972 |title= Effects of environment and juvenile hormone on ovaries of the wasp, Polistes metricus |journal= Insect Physiology |volume= 18 |issue= 1 |pages= 1875–1883 |doi= 10.1016/0022-1910(72)90158-8|bibcode= 1972JInsP..18.1875B }}</ref>

===Comparison of diapause periods===
The sensitive stage is the period when stimulus must occur to trigger diapause in the organism. Examples of sensitive stage/diapause periods in various insects:<ref name=Chapman404>The Insects; Structure and Function, 4th Edition. R.F. Chapman, Cambridge University Press, 1998. {{ISBN|0-521-57048-4}}, p 404.</ref><br/>
{| class="wikitable"
|-
| '''Scientific name''' || '''Common name''' || '''Sensitive stage''' || '''Diapause'''
|-
|''[[Southwestern corn borer|Diatraea grandiosella]]'' || Southwestern corn borer || early larval || late larval<ref>Bulletin of Entomological Research (1976), 66:75–79 Cambridge University Press, Copyright © Cambridge University Press 1976, Diapause of the southwestern corn borer, ''Diatraea grandiosella'' Dyar (Lepidoptera, Pyralidae): effects of a juvenile hormone mimic: G. M. Chippendalea1 and C.-M. Yina1a1, Department of Entomology, University of Missouri, Columbia, Missouri 65201, U.S.A.</ref>
|-
|''[[Sarcophaga crassipalpis]]'' || Flesh fly || early larval || pupa
|-
|''[[Sarcophaga argyrostoma]]'' || Flesh fly || mid to late larval || pupa
|-
|''[[Manduca sexta]]'' || Tobacco hornworm || late embryonic (egg) to late larval || pupa
|-
|''[[Colorado beetle|Leptinotarsa decemlineata]]'' || Colorado potato beetle || early adult || late adult
|-
|''[[Bombyx mori]]'' || Silkworm || late embryonic (egg) to early larval || embryonic
|-
|''[[Gypsy moth|Lymantria dispar]]'' || Spongy moth || late embryonic || late embryonic
|-
|''[[Monarch (butterfly)|Danaus plexippus]]'' || Monarch butterfly || early adulthood || adulthood
|-
|''[[Acronicta rumicis]]''
|Knott grass moth
|mid larval
|mid larval
|-
|''[[Codling moth|Cydia pomonella]]''
|Codling moth
|early to mid larval 
|mid larval<ref>{{Cite book|title=The Biology of the Codling Moth as the Basis for Its Control|last=Tadic|first=M.|publisher=Univerzitet U Beogradu|year=1957}}</ref>
|-
|''[[Gynaephora groenlandica]]''
|Arctic woolly bear moth
|mid larval
|mid larval<ref>Makarova, O. L.; Sviridov, A. V.; Klepikov, M. A. (2013-04-01). "Lepidoptera (Insecta) of polar deserts". Entomological Review. 93 (2): 225–239.{{doi|10.1134/S0013873813020115}}. [[International Standard Serial Number|ISSN]] 0013-8738.</ref>
|-
|''[[Cuterebra fontinella]]'' || Mouse botfly || mid larval || pupa<ref>
{{cite journal |vauthors=Scholl PJ|title=Gonotrophic Development in the Rodent Bot Fly ''Cuterebra fontinella'' (Diptera: Oestridae)|journal=Journal of Medical Entomology|volume=28|issue=3|pages=474–476|year=1991|doi=10.1093/jmedent/28.3.474|pmid=1875379}}</ref>
|-
|''[[Nothobranchius furzeri]]
|turquoise killifish
|egg
|egg
|}

===Induction===
The induction phase occurs at a genetically predetermined stage of life, and occurs well in advance of the environmental stress.<ref name="Kostal" /> This sensitive stage may occur within the lifetime of the diapausing individual, or in preceding generations, particularly in egg diapause.<ref name="Huffaker">Huffaker, C.B. and Gutierrez, A.P., Eds. 1999. Ecological Entomology. John Wiley & Sons, Inc.</ref> During this phase, insects are responsive to external cues called token stimuli, which trigger the switch from direct development pathways to diapause pathways. Token stimuli can consist of changes in [[photoperiod]], [[thermoperiod]], or [[allelochemicals]] from food plants. These stimuli are not in themselves favourable or unfavourable to development, but they herald an impending change in environmental conditions.<ref name="Tauber" />

===Preparation===
The preparation phase usually follows the induction phase, though insects may go directly from induction to initiation without a preparation phase.<ref name="Kostal" /> During this phase, insects accumulate and store molecules such as [[lipids]], [[proteins]], and [[carbohydrates]]. These molecules are used to maintain the insect throughout diapause and to provide fuel for development following diapause termination. Composition of the [[cuticle]] may be altered by changing [[hydrocarbon]] composition and by adding [[lipids]] to reduce water loss, making the organism resistant to desiccation.<ref>{{cite journal |last1= HEGDEKAR |first1= B. M. |year= 1979 |title= Epicuticular Wax Secretion in Diapause and Non-diapause Pupae of the Bertha Army worm |journal= Annals of the Entomological Society of America |volume= 72 |issue= 1 |pages= 13–15|doi= 10.1093/aesa/72.1.13 }}</ref> Diapausing [[pupa]]ria of the [[flesh fly]], ''Sarcophaga crassipalpis'', increase the amount of cuticular [[hydrocarbons]] lining the puparium, effectively reducing the ability of water to cross the cuticle.<ref>{{cite journal |last1= Yoder |first1= J.A. |last2= Denlinger |first2= D.L. |last3= Dennis |first3= M.W. |last4= Kolattukudey |first4= P.E. |year= 1992 |title= Enhancement of diapausing flesh fly puparia with additional hydrocarbons and evidence for alkane biosynthesis by a decarbonylation mechanism |journal= Insect Biochemistry and Molecular Biology |volume= 22 |issue= 3 |pages= 237–243 |doi=10.1016/0965-1748(92)90060-r|bibcode= 1992IBMB...22..237Y }}</ref>

===Initiation===
[[Photoperiod]] is the most important stimulus initiating diapause.<ref name=Chapman404/> The initiation phase begins when morphological development ceases.<ref name="Kostal" /> In some cases, this change may be very distinct and can involve [[ecdysis|moulting]] into a specific diapause stage, or be accompanied by color change. [[Enzyme|Enzymatic]] changes may take place in preparation for [[cold hardening]]. For example, only diapausing adults of the fire bug, ''Pyrrhocoris apterus'', have the enzymatic complement that allows them to accumulate [[polyol|polyhydric alcohols]], molecules that help to lower their freezing points and thus avoid freezing.<ref>{{cite journal |last1= Kostal |first1= V. |last2= Tollarova |first2= M. |last3= Sula |first3= J. |year= 2004 |title= Adjustments of the enzymatic complement for polyol biosynthesis and accumulation in diapausing cold-acclimated adults of Pyrrhocoris apterus |journal= Journal of Insect Physiology |volume= 50 |issue= 4|pages= 303–313 |doi=10.1016/j.jinsphys.2004.01.006|pmid= 15081823 |bibcode= 2004JInsP..50..303K }}</ref> Insects may also undergo behavioural changes and begin to aggregate, [[insect migration|migrate]], or search for suitable [[overwinter]]ing sites.[[File:Angangueo monarchs.jpg|thumb|Overwintering [[monarch butterflies]] in diapause clustering on [[oyamel]] trees. One tree is completely covered in butterflies. These butterflies were located on a preserve outside of [[Angangueo]], [[Michoacán]], [[Mexico]]]]

===Maintenance===
During the maintenance phase, insects experience lowered [[metabolism]] and developmental arrest is maintained.<ref name="Kostal" /> Sensitivity to certain stimuli which act to prevent termination of diapause, such as photoperiod and [[temperature]], is increased. At this stage, insects are unresponsive to changes in the [[natural environment|environment]] that will eventually trigger the end of diapause, but they grow more sensitive to these stimuli as time progresses.

===Termination===
In insects that undergo obligate diapause, termination may occur spontaneously, without any external stimuli.<ref name="Kostal" /> In facultative diapausers, token [[stimulus (physiology)|stimuli]] must occur to terminate diapause. These [[stimulus (physiology)|stimuli]] may include chilling, freezing, or contact with [[water]], depending on the environmental conditions being avoided. These stimuli are important in preventing the insect from terminating diapause too soon, for instance in response to warm weather in late fall. In the [[Edith's checkerspot]] butterfly, individuals must receive enough sunlight in order to terminate the diapause stage and become a fully grown butterfly.<ref name="ten">{{cite journal |last1=Weiss |first1=Stuart B. |last2=White |first2=Raymond R. |last3=Murphy |first3=Dennis D. |last4=Ehrlich |first4=Paul R. |title=Growth and Dispersal of Larvae of Checkerspot Butterfly Euphydryas editha |journal=Oikos |date=October 1987 |volume=50 |issue=2 |pages=161–166 |doi=10.2307/3565996 |jstor=3565996|bibcode=1987Oikos..50..161W }}</ref> Termination may occur at the height of unfavourable conditions, such as in the middle of winter. Over time, depth of diapause slowly decreases until direct development can resume, if conditions are favourable. Termination can also occur in specific time frames linked to reproductive periods, such as in the beetle ''[[Colaphellus bowringi]]:'' diapause ends for spring-reproducing beetles between late February and early April and for autumn-reproducing beetles between mid August and early October''.''<ref>{{Cite journal |last1=Xue |first1=Fang-Sen |last2=Li |first2=Ai-Qing |last3=Zhu |first3=Xing-Fen |last4=Gui |first4=Ai-Li |last5=Jiang |first5=Pei-Lan |last6=Liu |first6=Xiao-Fen |date=August 20, 2002 |title=Diversity in life history of the leaf beetle, Colaphellus bowringi Baly |url=https://www.sciengine.com/AESK/doi/10.16380/j.kcxb.2002.45.4.494498;JSESSIONID=737db758-13f2-4432-a9aa-1297abd9b7ed |journal=Acta Entomologica Sinica |volume=45 |issue=4 |pages=494–498|doi=10.16380/j.kcxb.2002.45.4.494498 |doi-broken-date=1 November 2024 }}</ref>

===Post-diapause quiescence===
Diapause frequently ends prior to the end of unfavourable conditions and is followed by a state of [[wikt:quiescence|quiescence]] from which the insect can arouse and begin direct development, should conditions change to become more favourable.<ref name="Kostal" /> This allows the insect to continue to withstand harsh conditions while being ready to take advantage of good conditions as soon as possible.