{{Short description|Species of fly}} {{Speciesbox | image = Ormia ochracea (gravid female).jpg | genus = Ormia | species = ochracea | display_parents = 3 | authority = (Bigot, 1889)<ref name="Bigot1889b">{{cite journal |last= Bigot |first= J. M. F. |date= 1889 |title= Dipteres nouveaux ou peu connus. 34e partie, XLII: Diagnoses de nouvelles especes|journal= Annales de la Société Entomologique de France |volume= 8 |issue= 6 |pages = 253–270 }}</ref> | synonyms = *''Phasiopteryx montana'' <small>Townsend, 1912</small> *''Pyrrosia ochracea'' <small>Bigot, 1889</small><ref name="Bigot1889b"/> }}
'''''Ormia ochracea''''' is a small yellow nocturnal fly in the family Tachinidae.<ref name="OHara2020">{{cite web |last1=O’Hara |first1=James E. |last2=Shannon |first2=J. Henderson |last3=D. Monty |first3=Wood |title=World Checklist of the Tachinidae |url=http://www.nadsdiptera.org/Tach/WorldTachs/Checklist/Tachchlist_ver2.1.pdf |website=Tachinidae Resources |access-date=28 February 2022 |date=5 March 2020}}</ref> It is notable for its parasitism of crickets and its exceptionally acute directional hearing. The female is attracted to the song of the male cricket and deposits larvae on or around him, as was discovered in 1975 by the zoologist William H. Cade.<ref name=":0">{{cite journal | last=Cade | first=W. | title=Acoustically Orienting Parasitoids: Fly Phonotaxis to Cricket Song | journal=Science | publisher=American Association for the Advancement of Science (AAAS) | volume=190 | issue=4221 | date=1975-12-26 | issn=0036-8075 | doi=10.1126/science.190.4221.1312 | pages=1312–1313| s2cid=85233362 }}</ref>
''Ormia ochracea'' is a model organism in sound localization experiments because of its unique "ears", which are complex structures inside the fly's prothorax near the bases of its front legs. The fly is too small for the time difference of sound arriving at the two ears to be calculated in the usual way, yet it can determine the direction of sound sources with exquisite precision. The tympanic membranes of opposite ears are directly connected mechanically, allowing resolution of nanosecond time differences<ref>{{cite journal | last1=Miles | first1=R. N. | last2=Robert | first2=D. | last3=Hoy | first3=R. R. | title=Mechanically coupled ears for directional hearing in the parasitoid fly Ormia ochracea | journal=The Journal of the Acoustical Society of America | publisher=Acoustical Society of America (ASA) | volume=98 | issue=6 | year=1995 | issn=0001-4966 | doi=10.1121/1.413830 | pages=3059–3070|pmid=8550933}}</ref><ref>{{cite journal | last1=Robert | first1=D. | last2=Miles | first2=R.N. | last3=Hoy | first3=R.R. | title=Directional hearing by mechanical coupling in the parasitoid fly Ormia ochracea | journal=Journal of Comparative Physiology A | publisher=Springer Science and Business Media LLC | volume=179 | issue=1 | year=1996 | issn=0340-7594 | doi=10.1007/bf00193432 | pages=29–44|pmid=8965258| s2cid=21452506 }}</ref> and requiring a new neural coding strategy. Various research groups have designed low-noise differential microphones inspired by ''O. ochracea''’s directionally sensitive hearing system.
== Distribution == ''Ormia ochracea'' is native to the southeastern United States, including states such as Texas and Florida.<ref name="Sabrosky1953">{{Cite journal|last=Sabrosky|first=C.W.|date=1953|title=Taxonomy and host relations of the tribe Ormiini in the Western Hemisphere (Diptera, Larvaevoridae)|journal=Proceedings of the Entomological Society of Washington|volume=55|pages=167–183}}</ref> ''O. ochracea'' is also found throughout North America, South America, and the Caribbean,<ref name=":1">{{Cite journal|last=Lehmann|first=Gerlind U.C.|date=January 2003|title=Review of Biogeography, Host Range and Evolution of Acoustic Hunting in Ormiini (Insecta, Diptera, Tachinidae), Parasitoids of Night-calling Bushcrickets and Crickets (Insecta, Orthoptera, Ensifera)|journal=Zoologischer Anzeiger - A Journal of Comparative Zoology|volume=242|issue=2|pages=107–120|doi=10.1078/0044-5231-00091|s2cid=85839051 |issn=0044-5231}}</ref> though its exact range is not known.
== Life history == ''Ormia ochracea'' has the full life cycle of egg, larvae, pupa, and adult. Once a female fly finds a suitable host, she deposits planidia (first instar larvae) which then quickly burrow into the host.<ref name=":3">{{Cite journal|last1=Wineriter|first1=S. A.|last2=Walker|first2=T. J.|date=December 1990|title=Rearing phonotactic parasitoid flies [Diptera: Tachinidae, ormiini, ormia spp.]|journal=Entomophaga|volume=35|issue=4|pages=621–632|doi=10.1007/bf02375096|s2cid=27347119 |issn=0013-8959}}</ref> The planidia develop within the body of the field cricket host, embedding initially in muscle before migrating into the abdomen.<ref name=":4">{{Cite journal|last1=Adamo|first1=S.A.|last2=Robert|first2=D.|last3=Hoy|first3=R.R.|date=March 1995|title=Effects of a tachinid parasitoid, Ormia ochracea, on the behaviour and reproduction of its male and female field cricket hosts (Gryllus spp)|journal=Journal of Insect Physiology|volume=41|issue=3|pages=269–277|doi=10.1016/0022-1910(94)00095-x|issn=0022-1910|doi-access=free}}</ref> The larvae molt within the host's abdomen and feed primarily on the host's muscle and fat. ''O. ochracea'' larvae typically complete development and emerge after about 7 days, which subsequently kills the host. The larvae pupate and emerge as adult flies approximately 2 weeks after emerging from the host.<ref name=":3" />
== Food resources == ''O. ochracea'' is a parasitoid known to prey on several species of ''Gryllus'' field crickets including ''Gryllus integer'', ''Gryllus rubens'', ''Gryllus texensis'', and ''Gryllus firmus''.<ref name=":1" /> Flies have been observed responding to various cricket songs, but seem to be limited to the family Gryllidae. The natural host of the fly may vary by location. Larvae of ''O. ochracea'' exhibit highest survival in its natural host and limited survival in other potential host species.<ref>{{Cite journal|last1=Thomson|first1=Ian R.|last2=Vincent|first2=Crystal M.|last3=Bertram|first3=Susan M.|date=March 2012|title=Success of the Parasitoid FlyOrmia ochracea(Diptera: Tachinidae) on Natural and Unnatural Cricket Hosts|journal=Florida Entomologist|volume=95|issue=1|pages=43–48|doi=10.1653/024.095.0108|issn=0015-4040|doi-access=free}}</ref>
=== Host-finding === [[File:Fall Field Cricket (Gryllus pennsylvanicus) - Kitchener, Ontario 2018-06-28.jpg|thumb|The field cricket is the common host for ''O. ochracea'']]In 1975, William H. Cade experimentally demonstrated that ''Ormia ochracea'' uses the mating call of the field cricket as a means to locate its host. Cade placed dead crickets on top of speakers playing cricket songs and various control sounds and recorded the amount of time the fly spent on either the control or test speaker. He found that flies spent more time on the speakers playing cricket songs and observed that the flies would always deposit larvae on and around the speaker which was playing cricket songs.<ref name=":0" />
==== Learning ==== ''O. ochracea'' have been shown to adjust their preference for host songs after exposure to different songs in the laboratory. In a 2011 study, flies that were previously exposed to the ''G. lineaticeps'' song chose the ''G. lineaticeps'' song over the ''G. integer'' song, and vice versa.<ref>{{Cite journal|last1=Paur|first1=Jennifer|last2=Gray|first2=David A.|date=October 2011|title=Individual consistency, learning and memory in a parasitoid fly, Ormia ochracea|journal=Animal Behaviour|volume=82|issue=4|pages=825–830|doi=10.1016/j.anbehav.2011.07.017|s2cid=18427803 |issn=0003-3472}}</ref> This preference was very short term. ''O. ochracea'''s flexible learning capabilities may have been critical in expanding its host and geographical range.
=== Effects of infestation on host behavior === ''O. ochracea'' infestation has been shown to affect the behavior and reproduction of host field crickets.<ref name=":4" /><ref name=":5">{{Cite journal|last1=Beckers|first1=Oliver M.|last2=Wagner|first2=William E.|date=April 2013|title=Parasitoid infestation changes female mating preferences|journal=Animal Behaviour|volume=85|issue=4|pages=791–796|doi=10.1016/j.anbehav.2013.01.025|pmc=3857093|pmid=24347669|issn=0003-3472|url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1240&context=bioscifacpub}}</ref> Early in the infestation period, non-reproductive behavior is largely unimpaired because the parasitic larvae do not consume the digestive system or central nervous system of the host.<ref name=":4" /> After the larvae migrate to the host's abdomen, the host's mating, egg-laying, and fighting ability decline, most likely due to tissue damage caused by the larvae.<ref name=":4" /> Additionally, infestation of female crickets alters their mating preferences. ''Gryllus lineaticeps'' females normally prefer to respond to male songs with intermediate chirp rates over those with slow chirp rates, but females parasitized by ''O. ochracea'' show no preference between chirp rates.<ref name=":5" /> Reduced selectivity in infested female ''G. lineaticeps'' may be adaptive, as a female may be more likely to reproduce before being killed by the parasitoids if they are less selective.
=== Host defenses === Some species of cricket which are parasitzed by ''O. ochracea'' have evolved methods to avoid infestation. For example, some members of the prey cricket ''Teleogryllus oceanicus'' have a mutation called flat wing, in which the sound-producing structures of the male forewings are erased.<ref>{{cite journal | last1=Pascoal | first1=Sonia | last2=Cezard | first2=Timothee | last3=Eik-Nes | first3=Aasta | last4=Gharbi | first4=Karim | last5=Majewska | first5=Jagoda | last6=Payne | first6=Elizabeth | last7=Ritchie | first7=Michael G. | last8=Zuk | first8=Marlene | last9=Bailey | first9=Nathan W. |display-authors=5| title=Rapid Convergent Evolution in Wild Crickets | journal=Current Biology | publisher=Elsevier BV | volume=24 | issue=12 | year=2014 | issn=0960-9822 | doi=10.1016/j.cub.2014.04.053 | pages=1369–1374| pmid=24881880 | doi-access=free }}</ref> The flat wing was first observed in 2003 on the Hawaiian island of Kauai, and was also found on neighbouring Oahu two years later. Genetic studies of crickets from each island show that the mutations arose from different genomic variations.
== Enemies == Because field crickets commonly sing at night, ''O. ochracea'' are susceptible to predation by bats. Studies have shown that ''O. ochracea'' has evolved an acoustic startle response to bat-like ultrasound, a response very similar to that of female crickets.<ref name=":2">{{Cite journal|last1=Rosen|first1=M. J.|last2=Levin|first2=E. C.|last3=Hoy|first3=R. R.|date=2009-11-27|title=The cost of assuming the life history of a host: acoustic startle in the parasitoid fly Ormia ochracea|journal=Journal of Experimental Biology|volume=212|issue=24|pages=4056–4064|doi=10.1242/jeb.033183|pmid=19946084|pmc=2784737|issn=0022-0949}}</ref> ''O. ochracea'' has also been shown to demonstrate a sharp response boundary between the frequencies of cricket song and bat ultrasound.<ref name=":2" />
== Physiology ==
=== Directional hearing === In order for an animal to localize sound, it must be able to detect minute differences in intensity and time between the arrival of the sound to the ear closer to the source and the ear further from the source. ''O. ochracea'' displays a remarkable ability to localize sound despite the incredibly small distance (450-520μm) between its acoustic sensory organs.<ref name=":6">{{Cite journal|last1=Miles|first1=R. N.|last2=Robert|first2=D.|last3=Hoy|first3=R. R.|date=December 1995|title=Mechanically coupled ears for directional hearing in the parasitoid fly Ormia ochracea|journal=The Journal of the Acoustical Society of America|volume=98|issue=6|pages=3059–3070|doi=10.1121/1.413830|pmid=8550933|issn=0001-4966}}</ref> Its sound localization ability is facilitated by a cuticular structure which joins its ears, mechanically coupling their motion and magnifying interaural differences by a factor of about 20.<ref name=":6" /> Prior to ''O. ochracea'' no similar mechanism of auditory localization had been described.
== Scientific significance == Several researchers have reported the construction of microphones inspired by the hearing system of ''O. ochracea.'' In 2009, R.N. Miles et al. designed and created a low-noise differential microphone inspired by the unique hearing system of ''O. ochracea'', for use in hearing aids''.'' The design of their microphone diaphragm, which measures 1 x 2 mm<sup>2</sup>, is based on the mechanically coupled ears of ''O. ochracea.'' Their microphone was found to have lower noise than commercially available hearing aid microphones while minimizing distance between sensors.<ref>{{Cite book|title=A low-noise differential microphone inspired by the ears of the parasitoid fly Ormia ochracea|last=Miles, R.N. Su, Q. Cui, W. Shetye, M. Degertekin, F.L. Bicen, B. Garcia, C. Jones, S. Hall, N.|date=April 2009|publisher=Acoustical Society of America|oclc=678236270}}</ref> In April 2015, a group from the University of Strathclyde and the MRC/CSO Institute for Hearing Research (IHR) announced that it had created a microphone based on ''O. ochracea'''s hearing system, and had been awarded a £430,000 grant by the U.K. Engineering and Physical Sciences Research Council to build and test the hearing aid for three years.<ref>{{cite magazine | last=Clark| first=Liat | title=Parasitic flies inspire potential revolution in hearing aids | magazine=WIRED UK | date=2015-04-21 | url=https://www.wired.co.uk/article/parasitic-flies-inspire-hearing-aid | access-date=2021-11-11}}</ref>
==References== {{Reflist}}
==External links== * {{ITIS |id=652559 |taxon=Ormia ochracea |accessdate=9 February 2006}} * [https://www.npr.org/programs/re/archivesdate/1999/jul/990712.ormia.html NPR show on the hearing of ''Ormia ochracea''] * {{US patent|7146014|U.S. patent for technology based on the fly's physiology}}
{{Taxonbar|from=Q3356515}}
Category:Tachininae Category:Taxa named by Jacques Marie François Bigot Category:Insects described in 1889 Category:Flies of North America Category:Flies of South America Category:Model organisms