Tephritid Flies of the Great Smoky Mountains National Park
In collaboration with the All Taxa Biological Survey (ATBI), Great Smoky Mountains National Park
Gary J. Steck and Bruce D. Sutton
Museum of Entomology
A Checklist, Species Accounts, and Images of the Tephritidae of the GSMNP
Tephritid flies, often known as fruit flies' because of a number of well-known fruit pests, are obligatory plant feeders whose biologies, phenologies, and distributions are tightly linked to their host plants. They display a diverse array of plant relationships, as there are not only fruit infesters, but also many species of gall-makers, leaf-miners, stem-miners, and seed and flower feeders. Each species is generally limited to a single host or narrow range of related host plants. However, different genera of tephritids are associated with a large variety of different plant families, which in turn are elements of different plant communities and successional stages. For example, many tephritid flies feed on stems, roots, flowers or seeds of Asteraceae, which are most abundant in highly disturbed or very early successional plant communities. Other genera, especially the fruit infesters, occur in plants of intermediate successional stages (e.g. Juniperus) as well as late successional stages in understory hosts such as Cornus, Ilex, Vaccinium, and others. Thus, tephritid fly diversity tracks plant and plant community diversity over broad areas such as the Great Smoky Mountains National Park. Better knowledge of groups such as the Tephritidae may be useful in making management decisions for the GSMNP.
The tephritid flies of North America are taxonomically well-known (see Foote, Norrbom and Blanc, 1993, Handbook of the Fruit Flies (Diptera: Tephritidae) of North America), but not so well known in biology, distribution, phenology, host plant relationships, and immature stages. This is especially true of the southern Appalachian region and southeastern United States in general. For example, Foote et al. mapped the distribution of all known tephritid taxa in North America (about 350 species), of which only 6-8 are shown as being present in the GSNMP. Even though most tephritids are showy (sometimes also called picture-winged flies') and therefore usually noticed and retained by insect collectors, many species are confined to very narrow habitats, and some might even be considered secretive. Thus, determination of their presence often requires very targeted collecting efforts. Our field work to date, together with records that we have excavated from other sources, has now demonstrated the presence of 45 species within the park boundaries, and we estimate that there are likely a total of about 60-70 species present. Interestingly, some species considered quite rare in North America we have found to be locally abundant in the Park. Also, we have greatly expanded by 100s of miles the known distributions of a number of taxa, including both common and rare species.
One of our major goals for the next 5 years is to document as thoroughly as possible the full range of tephritid taxa in the park and their basic biologies including host plants, phenologies, and immature stages.
As true for any natural history study, the primary activities consist of spending time in the field observing and collecting, followed by laboratory rearing, microscopic examination, identification, preservation, taxonomic description, etc. Specifically:
Determining likely host plants, locations and seasonality from published data.
Field time locating and examining likely host plants, and collecting host tissues for rearing. Two to four trips per year over several years, each of a week or more in duration, will be required, because the window of opportunity to discover adults and/or larval stages of each species is usually on the order of only a few weeks out of any given year.
Passive insect trapping in areas likely to yield specific taxa. Trapping is a valuable adjunct to hand-collecting and reveals presence of insects that are otherwise undetected, thus alerting one to the likely presence of nearby host plants Our experience has shown that 6-meter malaise traps are vastly superior to the more commonly used 6-foot traps in capturing aerial insects. The quantity and diversity of trapped taxa are several-fold greater in 6-m traps.
Removal of plant material to a laboratory setting to rear insects to adult stage to confirm identification (may require 9-12 months for univoltine insects).
Dissection of plant tissues to acquire immature stages, also revealing details of insect feeding, development time, mortality factors, and parasites and predators.
Permanent preservation, labeling, databasing of specimens.
Taxonomic description of life stages and new taxa.
Species list of tephritid flies of GSMNP with host plants and mapped distributions within the Park and other biological information
Prepared, labeled and identified specimens permanently preserved in the Florida State Collection of Arthropods (FSCA) and GSMP
Publication of results in peer-reviewed scientific journals
Thousands of other non-target specimens garnered from traps and hand-collections will be permanently preserved, stored, and transferred to cooperating scientists of the FSCA and other institutions according to their expertise and interests in advancing the goals of the ATBI
Field Trip Log:
(see the checklist/notes for species collected)
Malaise Trapping Sites
Cades Cove Newfound Gap Balsam Mountain
View from The Purchase
Photograph by Gary J. Steck
Malaise Trapping Sites in GSMNP
Biogeography of the tephritids of the GSMNP:
The tephritid fauna of the GSMNP, and the southern Appalachian Mountains in general, appears to be derived from large scale regional faunas and shows little, if any, endemism. Of the taxa recorded from within the boundaries of the GSMNP to date, excluding the members of the Strauzia longipennis complex which are too poorly differentiated for accurate distributions to be delimited, the majority (~40%) are members of a broad eastern North American regional fauna extending more or less from the Mississippi River basin eastward to the Atlantic coast, northward to southern Canada and southward into the southeastern coastal plain, often extending into at least northern Florida. An additional ~20% of this fauna is widely distributed throughout the USA, and at least some of these taxa may extend well beyond. Of the remaining ~40%, some 4% is generally northern USA to southern Canada in distribution, with an additional ~8% reaching a southern, or southeastern, extrema in the GSMNP region. In addition, ~16% of the GSMNP tephritid fauna has a more or less eastern and northern, though not necessarily strictly northeastern per se, distribution in the USA, perhaps extending into southeastern Canada, and reaching a southern extrema in the Southern Appalachians/GSMNP area. Interestingly, the remaining three taxa seem to be more localized in distribution with specimens collected only from the southern to middle Appalachian Mountains and nearby regions. These taxa, Rhynencina longirostris, Strauzia verbesinae, and Trypeta tortilis, have been considered as rather rare and seldom collected; however, we have found them to be locally abundant in the GSMNP wherever their larval hosts are to be found. Overall, the tephritid fauna of the GSMNP appears to have little affinity with the southeastern regional fauna of the USA beyond those taxa having a more or less broad eastern distribution. Curiously, while the southeastern regional tephritid fauna is extremely rich in species having larvae that feed in the flower heads of various Compositae (approximately 39% of all Florida taxa), while stem and leaf miners, and gall makers, are fairly uncommon (~23%), the reverse is true in the GSMNP. To date, rather few flower head feeding taxa have been encountered (~25% of taxa collected) in comparison with the miners and gall makers (~47% of total), and those taxa collected have not generally been found to be abundant. (The percentages for Florida include the fruit feeding Anastrepha of southern Florida and exotic fruitfly pests. If these are removed from consideration the number of fruit feeding tephritids in the GSMNP and Florida are similar and the percentages for flower feeders and miners/gall makers in Florida will increase. The ratio of flower feeders to miners/gall makers in Florida will remain consistent, however).
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