All Taxa Biodiversity Inventory - Great Smoky Mountains National Park

 

Diptera - Fruit flies


Rhynencina longirostris Johnson


Photograph by Jeffry Lotz - FDACS/DPI

Kingdom:

Phylum:

Class:

Order:

Family:

Animalia

Arthropoda

Insecta

Diptera

Tephritidae

Animals

Arthropods

Insects

Flies

Fruit flies

This species is the only North American representative of the genus Rhynencina, which otherwise includes only four other species that occur in South and Central America. Its larvae are seed feeders, and adults may be common wherever its host plant occurs in large patches. The host, Smallanthus uvedalius (Asteraceae), is an herbaceous perennial that is widespread in woods and meadows of the eastern United States. In the Park the host occurs at low elevations and in disturbed areas especially along roadsides. The fly has been collected outside of the Park in other Appalachian states (Pennsylvania, Maryland, North Carolina, and Georgia), but only rarely.

 


 

SPECIES DESCRIPTION

Size: 4-5 mm long.
Wing pattern: a broken pattern of narrow, vertical stripes typical of the tephritid tribe Myopitini.
Body color: yellow-brown.
Head: The face is swollen and protruding, thus earning the fly its specific epithet.
Oviscape: brown, tubular and swollen basally, abruptly narrowing in the middle; apical third is black.

 Photographs:

Rhynencina longirostris Adult Female, Metcalf Bottoms, Photograph by Jeffry Lotz - FDACS/DPI.
Rhynencina longirostris Adult on Host, Metcalf Bottoms, Photograph by Gary J. Steck.
Smallanthus uvadalius Host Photo #1, Cades Cove, August 2002, Photograph by Gary J. Steck.
Smallanthus uvadalius Host Photo #2, Cades Cove, August 2002, Photograph by Gary J. Steck.

Similar species: There are no close relatives of this fly nor flies of similar appearance in North America.

 DISTRIBUTION:
(GSMNP in green)

 Pennsylvania, Maryland, Tennessee (GSMNP), North Carolina, and Georgia

 In Park:

Cades Cove, Metcalf Bottoms, Abrams Creek campground, S end of Foothills Parkway (West), Straight Fork Road, Sugarlands.

 HOST PLANTS:

Smallanthus uvedalius (L.) Mackenzie ex Small (formerly Polymnia uvedalia), commonly known as leafcup or bearsfoot, is an herbaceous perennial that is widespread in woods and meadows of the eastern United States and flowers from summer to fall. Disk flowers are sterile, and thick achenes are produced from the ray flowers (Cronquist 1980).


Photograph by Gary J. Steck

 NATURAL HISTORY

 Habitat:

Wherever its host plant occurs, that is, at relatively low elevations below about 550 m and in disturbed areas especially along roadsides; both in open, sunny areas, and in moist, shaded understory.

Phenology

R. longirostris is univoltine with a flight-time corresponding to the flowering period of S. uvedalius, i.e., July-September in the GSMNP. Adults first appear at the host plants when the flower buds first begin to open. The duration of the individual life stages has not been well-documented, but adults probably live up to a few weeks, the egg stage probably lasts a few days, the larval stages up to a few weeks, and the pupal stage 10-11 months.

 Breeding and Courtship:

Males and females rendevous on the host plant for courtship and mating.

 Oviposition and Immature Stages:

Females oviposit into the young, soft achenes of S. uvedalius when flower buds attain a size of about 9-12 mm diameter. At the very beginning of the flowering season, when buds are scarce, a single achene may have several eggs oviposited into it; thereafter, females lay only a single egg into an achene and only one larva develops per achene. All of the immature stages develop within a single achene. Eventually, the seed head falls to the ground with the fly puparia trapped inside the hard achenes where they developed. Over a period of many months in the moist forest litter or soil, the achenes probably degrade sufficiently to allow adult flies to successfully emerge from the puparia.

 Predators and Parasites:

Adults probably fall prey to spiders, and possibly also to birds and lizards, although no incidents have yet been recorded. The larvae are heavily parasitized by a Heteroschema sp. (Hymenoptera: Pteromalidae).

 Community Ecology:

Immature stages of Rhynencina longirostris share their host plant seed heads with caterpillars of a pyralid moth, Homoeosoma sp. These caterpillars feed voraciously on the developing flowers and seeds, and may consume the fly larvae as well. Another tephritid fly, Strauzia uvedaliae, mines the stems of S. uvedalius, but probably has no direct effect on R. longirostris. The tephritid, Xanthaciura tetraspina, is commonly found on the flowers of S. uvedalius, but does not appear to breed in this species of composite.

 CONSERVATION BIOLOGY:

Populations of this fly depend on maintenance of its host plant populations, which, in turn, require regular disturbances to maintain open meadows and edges along forests and roadsides.

 Special Protection Status:

- Rangewide: None

- In Park: All plants and animals are protected within the Great Smoky Mountains National Park. Collection requires a permit which is usually granted only for research or educational purposes.


ACKNOWLEDGMENTS

 Text:

Gary J. Steck, Ph.D., Florida State Collection of Arthropods, Gainesville
Bruce D. Sutton, Florida State Collection of Arthropods, Gainesville

Photographs:

Jeffrey Lotz, Division of Plant Industry, Florida Department of Agriculture & Consumer Services, Gainesville
Gary J. Steck, Ph.D., Florida State Collection of Arthropods, Gainesville

Web Page Development:

Bruce D. Sutton, Florida State Collection of Arthropods, Gainesville

 

REFERENCES

Cronquist, A. 1980. Vascular flora of the southeastern United States. Vol. 1. Asteraceae. University of North Carolina Press, Chapel Hill, North Carolina, 261 pp.
Foote, R. H., F. L. Blanc, and A. L. Norrbom. 1993. Handbook of the fruit flies (Diptera: Tephritidae) of America north of Mexico. Cornell University Press, Ithaca, New York, 571 pp.
Freidberg, A. and A. L. Norrbom. 1999. A generic reclassification and phylogeny of the tribe Myopitini (Tephritidae), pp. 581-637. In Aluja, M. and A. L. Norrbom, eds., Fruit Flies (Tephritidae): Phylogeny and Evolution of Behavior. CRC Press, Boca Raton, Florida, 944 pp.
Steck, G. J. and B. D. Sutton. 2000. New records for Tephritidae (Diptera: Tephritidae) in Great Smoky Mountains National Park. Insecta Mundi 14: 256.
Steck, G. J., B. D. Sutton, and D. DeFoe. 2002. Biology of Rhynencina longirostris Johnson (Diptera: Tephritidae). Proceedings of the Entomological Society of Washington (in press).

 

GLOSSARY

achene - The fruit produced by members of the family Asteraceae comprising a single seed and its enveloping shell.
oviposition - The act of laying eggs.
oviscape - The hardened sheath enclosing the needle-like ovipositor, or egg-laying structure, of female tephritid flies.
puparium - The hardened, cocoon-like structure, unique to Diptera, which develops from the cast 3rd instar skin, within which metamorphosis from pupa to adult takes place.
univoltine - Having one generation per year.


Please send any questions or comments to G. J. Steck or B. D. Sutton

Last Updated: October 3, 2002