Symphyta (Sawfly) species richness in an U.S. Mid-Atlantic national park

Background/Question/Methods

Symphyta (Sawflies) comprises about 9,000 species in 14 families and occurs worldwide in many terrestrial habitats where their larvae consume foliage, stems, and wood, and adults consume leaf pubescence, moisture, nectar, other insects, or a combination of these things, depending on the species.  Larvae are external leaf feeders, gall formers, leaf miners, and stem and wood borers of a diverse flora of mosses, ferns, conifers, and herbaceous and woody flowering plants.  Some species can cause economic damage to crops, forests, and ornamental plants.  Our study examines symphytan species identities, flight times, and abundances in three parks within the George Washington Memorial Parkway (GWMP), an U.S. national park in Maryland, Virginia, and Washington, D.C.  Our samples are from Townes-style Malaise traps and hand-collecting in a rare, tidal, freshwater marsh; a floodplain forest; a swamp; and an upland forest in the Piedmont and Coastal Plain Geological Provinces.  Our research questions, include (1) which species are present in each park and habitat, (2) how similar are the species compositions among parks, (3) what are their flight times, and (4) more specifically, what are the species and their abundances in three habitats of Dyke Marsh Wildlife Preserve (DMWP), one of the GWMP parks?

Results/Conclusions

This is the first quantitative symphytan survey that includes a freshwater, tidal marsh, and the second comprehensive symphytan survey for U.S. national parks.  Our sample is composed of 174 species in 10 families, which is 74% of the known species richness of Great Smoky Mountains National Park and 50% of the known species richness of the State of Virginia.  As a group, the GWMP symphytans flew from March through October, being more common in March through June.  Our sample included some bivoltine and multivoltine species and many univoltine species.  Coefficients of community of the sampled GWMP parks ranged from 0.11 through 0.34.  In DMWP, symphytans were most common in the forest, followed by the forest-marsh ecotone, and the marsh.  Our sample included a rarely-collected symphytan, recorded as a leafminer of Mertensia virginica (Boraginaceae), and an unknown species feeding on Staphylea trifolia (Staphyleaceae) as larvae.  In this time of rapid global change, threats to the GWMP include air, soil, and water pollution; many alien, invasive species; flooding; and erosion.  Symphyta is very species rich in this park, making it an appropriate taxon for monitoring the health of GWMP in forthcoming years.