SYSTEMATICS AND ECOLOGY OF NET-WINGED MIDGES AND ASSOCIATED AQUATIC INSECTS

Goals / Objectives
The overall objective of this research is to investigate the systematics and ecology of aquatic insects, especially net-winged midges (Diptera:Blephariceridae) and related taxa. Aspects of the following topics will be examined: (i) systematics i.e., faunistics, taxonomy, phylogeny and biogeography; (ii) structural and life-history adaptations to aquatic habitats; and (iii) reproductive and ecological isolation of sympatric species. Specific areas of research include: 1) Regional studies of biodiversity / faunistics; 2) Revisionary studies, including analysis of morphological characters of all life stages, description of new species and previously unknown life stages, and the development of keys for various life stages; 3) Phylogenetic analyses using a variety of character systems; 4) Biogeographical analyses of North American and world faunas; 5) Chromosomal analyses to help identify species and sibling species, evaluate geographic isolation of species, sibling species and populations, construct cytophylogenies of species and sibling species, and test for phylogenetic congruence between chromosomal and morphological characters; 6) Ecological studies to elucidate, compare and contrast life histories of sympatric species and sibling species, and identify reproductive and ecological isolation mechanisms.

Project Methods
Faunistic and revisionary studies will utilize museum specimens and specimens gathered in the field. Structural features will be ascertained from whole-animal preparations, slide mounts, dissections and scanning electron microscopy. Work will include comparative morphology, descriptions of new species, redescriptions of taxa, keys to all life stages, and phylogenetic analyses. Characters of all life stages will be analyzed, but with emphasis on pre-imaginal stages and on characters not previously examined in these taxa (e.g., chromosomes). Material for chromosomal analysis will be collected from a broad geographic area and prepared according to standard methods. Chromosomal attributes of each species will be recorded on photomicrographs and summarized on idiograms. Reconstructed cytophylogenies will be compared with phylogenies based on traditional morphological features. Phylogenetic and biogeographic relationships will be evaluated according to cladistic methods. Ecological data will be gathered during the course of routine field collections, using both qualitative and quantitative methods.

Progress 01/01/98 to 12/31/03

Outputs
ECOLOGY OF BLEPHARICERIDAE. Studies in the Appalachian Mountains showed distinct seasonal patterns among sympatric species and provided evidence of microhabitat and dietary specialization. Research confirmed that net-winged midges are trophically important as primary consumers and as a food resource for vertebrate predators. Furthermore, because blepharicerids inhabit clean, cool, well-oxygenated streams, these flies are a valuable bioindicator of water quality. Data gathered in this study suggest that most species are highly sensitive to perturbations, but some species are relatively tolerant of impacts. The taxonomic keys developed in this research will permit researchers and resource managers to identify resident species, and, thereby, assess stream quality. TAXONOMY OF BLEPHARICERA. Samples were collected from more than 400 sites, most in eastern North America. The Blepharicera collection amassed during this study is the largest and most diverse in the world. New collections supplement previous records and provide a relatively complete understanding of the biodiversity and distribution of North American Blepharicera. More importantly, these collections led to the discovery of eight new species, the resurrection of a previously synonymized species, and collections of previously unknown life stages for all species. This more than doubled the known diversity of the eastern fauna. GLOBAL BIODIVERSITY OF BLEPHARICERIDAE. Studies have focused on Eurasia, Central America, and Australia, with funding partly from other sources (National Geographic Society, National Science Foundation, Government of Thailand). Material collected during these and earlier surveys have provided the basis for taxonomic revisions, published keys, and web-based keys for larvae, pupae, and adults of genera. This work also led to a reinterpretation of adult genitalia and provided the basis for a comparative study of all Diptera. Other aspects of this research appear in publications on Madagascar, Costa Rica, Malaysia, and Central America. GLOBAL BIODIVERSITY OF AQUATIC INSECTS. Ongoing projects include collaborations with students and faculty at the University of Missouri, University of California - Davis, California State University - Sacramento, Slovene Natural History Museum, Kasetsart University, and Chiang Mai University. Field work in Nepal, northeastern Australia, and throughout Thailand has led to the discovery of new genera and many new species of aquatic insects.

Impacts
This research provided insights into the systematics and ecology of net-winged midges and associated aquatic insects. Samples collected in this research have provided new genera and many new species of aquatic insects. This material, particularly type specimens, will provide an authoritative reference collection for future educators and researchers in aquatic entomology and systematics. The educational value of this collection and the training of personnel are among the lasting products. Data on the diversity, distribution, relative abundance, and natural history of these insects have provided insights into potential bioindicators of water quality. These data will permit identification of areas of local endemism and sites of phylogenetic and biogeographic significance, which will have implications in the conservation and management of aquatic habitats. Other products include a database and web site on net-winged midges, which will be useful to systematists, aquatic- and fisheries biologists, biogeographers, conservationists, and resource managers.

Publications

Courtney, G.W. 2002. Phylogenetic relationships of nematocerous Diptera: synopsis of recent hypotheses. Proceedings of the Fifth International Congress of Dipterology. pg. 41. [abstract]
Courtney, G.W. 2002. Mountains, midges and monsoons: biosystematics of torrenticolous flies. Bulletin of the Entomological Society of Queensland, December.
Courtney, G.W. 2003. Blephariceridae. pp. 702-708 in S.M. Goodman & J.P. Benstead (editors). The Natural History of Madagascar. University of Chicago Press.
Merritt, R.W., G.W. Courtney. & J.B. Keiper. 2003. Diptera. pp. 324-340 in V.H. Resh & R.T. Carde (editors). Encylopedia of Insects. Academic Press, London.
Courtney, G.W. 2004. Blephariceridae. In M. Springer, P. Hanson, and A. Ramirez (editors). Los Artropodos y Moluscos de Agua Dulce de Costa Rica. [in press]
Courtney, G.W. 2004. Deuterophlebiidae. In C. Yule and Y.H. Sen (editors). An Introduction to the Freshwater Invertebrates of Malaysia and Singapore. Academy of Sciences Malaysia. [in press]
Courtney, G.W. 2004. Nymphomyiidae. In C. Yule and Y.H. Sen (editors). An Introduction to the Freshwater Invertebrates of Malaysia and Singapore. Academy of Sciences Malaysia. [in press]
Courtney, G.W. 2004. Blephariceridae. In B.V. Brown, A. Borkent, D.M. Wood, and M. Zumbado (editors). Manual of the Diptera of Central America. [in press]

Progress 01/01/02 to 12/31/02

Outputs
ECOLOGY OF NORTH AMERICAN NET-WINGED MIDGES. Publication of dietary studies of net-winged midges from eastern North America was completed. Research showed distinct dietary specialization and seasonality among sympatric species, and provided additional evidence that these insects are trophically significant and a potentially valuable bioindicator of water quality. GLOBAL BIODIVERSITY OF NET-WINGED MIDGES. Studies of world Blephariceridae and related aquatic insects focused on the Oriental and Australasian regions. Material collected during these and earlier surveys provided the basis for taxonomic revisions of the genus Horaia and related taxa (Blephariceridae: Apistomyiini) and of the regional faunas of south- and southeast Asia. Other regional studies have pertained to Madagascar, Costa Rica, Malaysia, and Central America. Data gathered in these and other studies have provided comparative material for not only net-winged midges, but for all Diptera. GLOBAL BIODIVERSITY OF AQUATIC INSECTS. Ongoing projects in Thailand are funded partly by the National Science Foundation and the Government of Thailand, and include collaborations with students and faculty at Clemson University, University of Missouri - Columbia, University of California - Davis, California State University - Sacramento, Slovene Natural History Museum, Kasetsart University, and Chiang Mai University. Biotic surveys during 2002 included a September visit to northeastern Australia and spring and fall collecting trips to northern Thailand. These collections resulted in many new records and taxa for all major groups of aquatic insects.

Impacts
This research provided valuable data about the systematics and ecology of net-winged midges and other aquatic insects. Specimens collected in this research have been studied by the Courtney lab and other scientists in North America and elsewhere, and have provided new genera and many new species of aquatic insects. Because some of these insects are sensitive to environmental perturbations, these collections and data have important implications in the conservation and management of aquatic habitats.

Publications

Alverson AJ and GW Courtney. 2002. Temporal patterns of diatom ingestion by larval net-winged midges (Diptera: Blephariceridae: Blepharicera). Freshwater Biology 47:2087-2097.
Gibson JF. 2002. A revision of the genus Horaia Tonnoir (Diptera: Blephariceridae: Blepharicerinae: Apistomyiini). M.S. thesis, Iowa State University, Ames. 82pp.

Progress 01/01/01 to 12/31/01

Outputs
Progress: This project includes the systematics and ecology of net-winged midges (Diptera:Blephariceridae) and related aquatic flies. ECOLOGY OF NORTH AMERICAN NET-WINGED MIDGES Dietary studies of net-winged midges from eastern North America were completed and showed distinct microhabitat and dietary specializations and seasonal patterns among sympatric species. Research provided evidence that net-winged midges are trophically significant as primary consumers and are a potentially valuable bioindicator of water quality. BIODIVERSITY OF NET-WINGED MIDGES Ongoing studies of world Blephariceridae and related aquatic flies have focused on Eurasia and Central America. Work during 2001 included field surveys in northern and central Thailand. Several new species of net-winged midges were discovered. Reviews of the net-winged midges and related flies from Madagascar, Costa Rica, Central America, and Malaysia were conducted and provide ecological and taxonomic information about the resident fauna. BIODIVERSITY OF AQUATIC INSECTS OF THAILAND The biota of Southeast Asia is one of the richest, most endemic, and most endangered in the world. Concerns about deforestation and loss of species have led to the area being recognized as a global biodiversity hotspot, underscoring the richness, endemism, and immediate threat to the biota. Field trips during May 2001 (and previous years) provided opportunities to train Thai students, collect several new species of insects, and gather ecological data about various taxa.

Impacts
This research provided compelling insights into the ecology and biodiversity of net-winged midges. Specimens collected in this research will be a valuable resource for future scientists, including scientists in North America and elsewhere. Because of their potential value as bioindicators of water quality, data on these insects will have important implications in the conservation and management of aquatic habitats.

Publications

Alverson AJ, GW Courtney and MR Luttenton. 2001. Niche overlap of sympatric Blepharicera larvae (Diptera:Blephariceridae) from the southern Appalachian Mountains. Journal of the North American Benthological Society 20:564-581.
Gibson JF and Courtney GW. 2001. Generic boundaries among Asian Apistomyiini (Diptera:Blephariceridae:Blepharicerinae) based on morphology of the immature stages. Bulletin of the North American Benthological Society 18:143.

Progress 01/01/00 to 12/31/00

Outputs
This project includes revisionary systematics and ecological studies of net-winged midges (Diptera: Blephariceridae) and related aquatic flies. REVISIONARY SYSTEMATICS AND ECOLOGY OF BLEPHARICERA This group of net-winged midges is one of the most widespread and diverse in Eurasia and North America. The collection amassed during my study is the largest in the world. New collections supplement previous records and provide a relatively complete understanding of the biodiversity and distribution of North American species. A recent revision of the fauna included discovery of several new species and previously unknown life stages for other species. This work led to published and web-based keys for larvae, pupae, and adults. Ecological studies of blepharicerids from the Appalachian Mountains showed distinct seasonal patterns among sympatric species and provided evidence of microhabitat and dietary specializations. Research has confirmed that net-winged midges are trophically important as primary consumers and as a food resource for vertebrate predators. Furthermore, because blepharicerids inhabit clean, cool, well-oxygenated streams, these flies are a potentially valuable bioindicator of water quality. Data gathered in this study suggest that most species are highly sensitive to perturbations, but some species are relatively tolerant of impacts. The taxonomic keys developed in this research will permit researchers and resource managers to identify resident species, and, thereby, assess stream quality. BIODIVERSITY OF ASIAN NET-WINGED MIDGES Ongoing studies of world Blephariceridae have focused on Eurasia and Central America. Work during 2000 included surveys of Thailand and Nepal. In addition to Blepharicera, other genera are known from this region and include some of the most primitive species. Unfortunately, records from the area are few and resident species are largely undescribed. Much of this work remains preliminary; however, currently available data include published and web-based keys for larvae, pupae, and adults of genera. This work led to a reinterpretation of adult genitalia and provided the basis for a comparative study of larval Diptera. BIODIVERSITY OF AQUATIC INSECTS OF THAILAND The biota of Southeast Asia is one of the richest, most endemic, and most endangered in the world. Recent concerns about deforestation and concomitant loss of biodiversity prompted Conservation International to identify the Indo-Burma region as a global biodiversity hotspot, underscoring the richness, endemism, and immediate threat to the biota. My projects in the area focus on aquatic insects of Thailand and involve collaborations with Kasetsart and Chiang Mai universities. The major goals are to discover and describe new species; document the distribution, abundance, and natural history of species; construct keys to aquatic taxa; and develop a database and website for faunal data.

Impacts
This research has led to the discovery of new species, previously unknown life stages of described species, and important records of other aquatic insects. Samples collected in this research, particularly type specimens, will be a valuable resource for future scientists. It provides an authoritative reference collection for educators and researchers in aquatic entomology and systematics, and for future revisionary, phylogenetic, and biogeographic studies. The educational value of this collection and the training of personnel are among the lasting products. Data on the diversity, distribution, relative abundance, and natural history of these insects also have provided insights into potential bioindicators of water quality. These data will permit identification of areas of local endemism and sites of phylogenetic and biogeographic significance, which will have important implications in the conservation and management of aquatic habitats. Other products include a database and web site on net-winged midges, which will be useful to insect systematists, aquatic- and fisheries biologists, biogeographers, conservationists, and resource managers.

Publications

Courtney GW and RM Duffield. 2000. Net-winged midges (Diptera:Blephariceridae): a food resource for Brook Trout in montane streams. Pan-Pacific Entomologist 76:87-94.
Courtney GW, B Sinclair and R Meier. 2000. 1.4. Morphology and terminology of Diptera larvae. pp. 85-161 in L. Papp & B. Darvas (editors). Manual of Palaearctic Diptera. Volume 1. Science Herald, Budapest. 978 pp.
WEBSITE DEVELOPMENT / REVISION. 2000. Blepharicerid biology: http://www.ent.iastate.edu/dept/research/systematics/bleph/biology.ht ml Classification: http://www.ent.iastate.edu/dept/research/systematics/bleph/classifica tion.html Interactive taxonomic keys: http://www.ent.iastate.edu/dept/research/systematics/bleph/keys/
Alverson AJ. 2000. Feeding ecology of larval net-winged midges (Diptera:Blephariceridae:Blepharicera) from the southern Appalachian Mountains. M.S. thesis, Iowa State University, Ames. 124pp.
Alverson AJ and Courtney GW. 2000. Temporal changes in the diets of larval net-winged midges (Diptera:Blepharceridae:Blepharicera) from Great Smoky Mountain National Park, North Carolina. Bulletin of the North American Benthological Society 17:136.
Alverson AJ, GW Courtney and MR Luttenton. 2000. Dietary characteristics and food overlap in the larvae of sympatric net-winged midges (Diptera:Blephariceridae:Blepharicera) from the southern Appalachian Mountains. Journal of the North American Benthological Society [accepted with revision]
Courtney GW. 2000. Revision of the net-winged midges of the genus Blepharicera Macquart (Diptera:Blephariceridae) of eastern North America. Memoirs of the Entomological Society of Washington 23:1-99.
Courtney GW. 2000. A.1. Blephariceridae. pp. 7-30 in L. Papp & B. Darvas (editors). Manual of Palaearctic Diptera. Appendix. Science Herald, Budapest. 604 pp.

Progress 01/01/99 to 12/31/99

Outputs
This project includes revisionary systematics and ecological studies of net-winged midges (Diptera:Blephariceridae) and related aquatic flies. Revisionary Taxonomy: Since the start of the project, net-winged midges have been collected from approximately 400 sites, most from eastern North America. The Blepharicera collection amassed during this study is the largest and most diverse in the world. New collections supplement previous records and provide a relatively complete understanding of the biodiversity and distribution of North American Blepharicera. More importantly, these collections led to the discovery of eight new species, the resurrection of a previously synonymized species, and collections of previously unknown life stages for all species. This more than doubled the known diversity of the eastern fauna. All descriptive work is complete, including: a) descriptions of larvae and pupae of new species and previously unknown stages of described species; b) construction of keys for larvae, pupae, and adults of Holarctic genera and of Nearctic species of Blepharicera; both are also available as interactive, web-based keys; c) illustrations and light- and scanning electron micrographs of larvae, pupae, and adults of all species. In addition, this work has led to a reinterpretation of adult genitalic homologies and provided the framework for a comparative study of larval Diptera. Ecological studies: Phenologies. Quantitative and qualitative samples permit identification of distinctive seasonal patterns (e.g., winter, spring, and summer species) among sympatric species. Microhabitat. Samples have provided evidence of microhabitat specialization, based partly on current (e.g. "low velocity" and "high velocity") specialists. Feeding. As part of investigating ecological partitioning among sympatric species, we are studying the feeding ecology of larval Blepharicera from different sites, microhabitat and season. Significant differences among species and between seasons have been recorded. Trophic Role. This research has demonstrated that net-winged midges can be important to stream ecosystem structure and function. In some streams, densities of immature stages exceeded 1000/m2, making blepharicerids the dominant grazer and one of the most abundant insects. The trophic contributions of blepharicerids extend to their importance as trout food. Bioindicators. Because blepharicerids inhabit clean, cool, well-oxygenated streams, these flies are a potentially valuable bioindicator of water quality. However, such determinations require baseline data on diversity, distribution, and natural history. Although blepharicerids are considered sensitive bioindicators, the data gathered in this study suggest that some species of Blepharicera are quite tolerant of impacts. The taxonomic keys developed in this research will permit researchers and resource managers to identify resident species and, thereby, determine if the fauna represents an assemblage of tolerant or sensitive groups.

Impacts
This research led to the discovery of 8 new species and important records of described species. Published and web-based keys will permit researchers and resource managers to identify species. Specimens collected in this research, particularly types, will be a valuable resource for future scientists. This research has shown these flies to be an important trophic resource and bioindicator.

Publications

Alverson, A.J. and Courtney, G.W. 1999. Food overlap in the diet of larval net-winged midges (Diptera:Blephariceridae:Blepharicera) from the southern Appalachian Mountains. Bulletin of the North American Benthological Society 16:115.
Courtney, G.W. 2000. A.1. Family Blephariceridae. In: Contributions to a Manual of Palaearctic Diptera. L. Papp and B. Darvas (editors). Appendix. Science Herald, Budapest. [in press]
Courtney, G.W. and Duffield, R.M. 2000. Net-winged midges (Diptera:Blephariceridae): a food resource for Brook Trout in montane streams. Pan-Pacific Entomologist. [in press]
Courtney, G.W., Sinclair, B., and Meier, R. 2000. 1.4. Morphology and terminology of Diptera larvae. In: Contributions to a Manual of Palaearctic Diptera. L. Papp and B. Darvas (editors). Volume 1. Science Herald, Budapest. [in press]

Progress 01/01/98 to 12/31/98

Outputs
This project includes revisionary systematics and ecological studies of net-winged midges (Diptera:Blephariceridae) and related aquatic flies. Investigations have focused on N. American species of the genus Blepharicera. Revisionary Taxonomy: (1) Collections: Net-winged midges have been collected at over 300 sites, most in eastern N. America. New records provide a relatively complete understanding of the biodiversity and distribution of N. American Blepharicera. More importantly, samples have provided several new species and records of many poorly known species. The latter include collections of the previously unknown immature stages of several species. (2) Descriptive work: Most of the descriptive work is finished, including (a) descriptions and illustrations of new species and previously unknown life-stages of described species; and (b) construction of keys for larvae, pupae and adults of all N. American Blepharicera. Ecological Studies: (1) Phenologies: Quantitative and qualitative samples permit identification of distinctive seasonal patterns among sympatric species. (2) Microhabitat: Samples provide evidence of microhabitat specialization, based partly on current: e.g. "low velocity" and "high velocity" specialists. Some species were even more restricted in microhabitat (e.g., only in splash zones along stream margins). (3) Feeding: As part of investigating ecological partitioning among sympatric species, ISU has begun studies of the feeding ecology of larval Blepharicera from different sites, microhabitat and season. Significant differences among species and between seasons have been recorded. IMPACTS OF RESEARCH: Taxonomy and Biodiversity: Although net-winged midges are widespread, distinctive, and ecologically sensitive, the group is poorly known. Taxonomic data are especially scarce for larvae and pupae, the stages encountered most often in ecological studies and, consequently, the stages for which keys are needed most. A major accomplishment of this project is provision of taxonomic keys. Biodiversity data are lacking for most insects, even for groups in N. America. Data permit identification of areas of endemism and sites of evolutionary significance, which are important for not only scientific reasons but for their implications in the conservation and management of streams. Research at ISU is providing these data. Trophic Role: Diptera are critical to the structure and function of freshwater ecosystems. Although the trophic significance of net-winged midges has been under-appreciated, we have recorded densities >1000/m2 at some sites. These data suggest that net-winged midges provide substantive biomass and a potentially significant food for gamefish. The latter has been confirmed through recent studies at ISU. Bioindicators: Net-winged midges inhabit cool, clean, well-oxygenated streams, and are one of the more sensitive bioindicators of water quality. However, their use as bioindicators is difficult without data on their diversity, distribution, and ecology. Studies at ISU are providing these data.

Impacts
(N/A)

Publications

Courtney, G.W. 1998 First records of the Nymphomyiidae (Diptera) in Nepal. Proceedings of the Entomological Society of Washington 100:595-597.
Courtney, G.W. 1998. A method for rearing pupae of net-winged midges (Diptera:Blephariceridae) and other torrenticolous flies. Proceedings of the Entomological Society of Washington 100:742-745.
Courtney, G.W. and Jedlicka, L. 1997. Nymphomyiidae. pp. 21-27 in L. Papp and Darvas, B. (editors). Manual of Palaearctic Diptera. Volume 2. Science Herald, Budapest. [published 1998].
Jedlicka, L. and Courtney, G.W. 1997. Deuterophlebiidae. pp. 13-19 in L. Papp and Darvas, B. (editors). Manual of Palaearctic Diptera. Volume 2. Science Herald, Budapest. [published 1998].
Alverson, A.J. and Courtney, G.W. 1998. Food overlap and temporal changes in the diet of larval net-winged midges (Diptera:Blephariceridae:Blepharicera) from the southern Appalachian Mountains. Bulletin of the North American Benthological Society 15:177. [abstract].
Alverson, A.J. and Courtney, G.W. 1998. Food overlap and temporal changes in the diet of larval net-winged midges (Blephariceridae:Blepharicera). Proceedings of the Fourth International Congress of Dipterology. pp. 7-8. [abstract].
Courtney, G.W. 1998. Endemism, sympatry and a plethora of new species: net-winged midges (Diptera:Blephariceridae:Blepharicera) from the Appalachian Mountains. Bulletin of the North American Benthological Society 15:168. [abstract].
Courtney, G.W. 1998. Mouthpart morphology of larval net-winged midges (Blephariceridae): ontogenetic and intergeneric comparisons and their phylogenetic implications. Proceedings of the Fourth International Congress of Dipterology. pp. 40-41. [abstract].