Ormia ochracea

Ormia ochracea
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Diptera
Family:	Tachinidae
Genus:	Ormia
Species:	O. ochracea
Binomial name
Ormia ochracea (Bigot, 1889)
Synonyms
Phasiopteryx montana Townsend, 1912 Pyrrosia ochracea Bigot, 1889

Ormia ochracea is a small yellow nocturnal fly, a parasitoid of crickets. It is notable because of its exceptionally acute directional hearing. The female is attracted by the song of the male cricket and deposits larvae on or around him, as was discovered in 1975 by the zoologist William H. Cade^[1]. The fly is found throughout the southern the US and into Mexico, though its exact range is not known.

The mating call of the male field cricket is used by Ormia ochracea in locating the cricket. Once a female fly finds a host (male cricket) she deposits a larva which then quickly burrows into the host, emerging about 7 - 10 days later, killing the host. Flies have been observed responding to a variety of cricket songs^[2], but seem to be limited to the family Gryllidae.

Ormia ochracea has become 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 their front legs. The animal 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^[3][4] and requiring a new neural coding strategy.^[5] Efforts to build directional microphones based on the structure of the fly's ear are underway.

References

1. ^ Cade, W. H. 1975. Acoustically orienting parasitoids: Fly phonotaxis to cricket song. Science 190: 1312-1313.
2. ^ Gray D.A., Banuelos C., Walker S.E., Cade W.H. & Zuk M. Behavioural specialization among populations of the acoustically orienting parasitoid fly Ormia ochracea utilizing different cricket species as hosts. Animal Behaviour, 2007, 73: 99-104
3. ^ Miles RN, Robert D, Hoy RR. Mechanically coupled ears for directional hearing in the parasitoid fly Ormia ochracea. J Acoust Soc Am. 1995 Dec;98(6):3059-70. PMID 8550933 doi:10.1121/1.413830
4. ^ Robert D, Miles RN, Hoy RR. Directional hearing by mechanical coupling in the parasitoid fly Ormia ochracea. J Comp Physiol [A]. 1996;179(1):29-44. PMID 8965258 doi:10.1007/BF00193432
5. ^ Mason AC, Oshinsky ML, Hoy RR. Hyperacute directional hearing in a microscale auditory system. Nature. 2001 Apr 5;410(6829):686-90. PMID 11287954 doi:10.1038/35070564

External links

• "Ormia ochracea". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=652559. Retrieved 9 February 2006. 
• NPR show on the hearing of Ormia ochracea
• U.S. patent for technology based on the fly's physiology