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The Bat Flies of La Selva -- About Bat Flies

Using This Resource
The Hippoboscoidea (Diptera, Calyptratae)
Collecting Bias
Assessment of Inventory Completeness
Literature Cited
The ALAS Project
Key Works in New World Bat fly Taxonomy
Acknowledgments


Using This Resource

Each species page includes photographic images of a bat fly species, bibliographic references to recent taxonomic papers that include descriptions or figures of the species, and the host species associated with the parasite in the data collected. The host association data does not necessarily include all globally know host records for a parasite species, only those collected in the vicinity of La Selva Biological Station (La Selva), and Braulio Carrillo National Park (Braulio Carrillo), and El Gavilán Ecological Reserve (El Gavilán), all in Heredia Province, Costa Rica. Notes clarifying difficulties with taxonomy are also included if necessary. Species pages can be accessed from the alphabetical list of bat fly species, from the list of bat species with their known associated parasites, or through the dichotomous key. All bat fly specimens will be deposited with the ALAS collection in La Selva, Costa Rica.

The Hippoboscoidea (Diptera, Calyptratae)

The Hippoboscoidea is a clade of calypterate flies containing the families Glossinidae, Hippoboscidae, Streblidae and Nycteribiidae. Hippoboscoids are obligate blood-feeders that prey on mammals and birds. Hippoboscoids are characterized by a viviparous developmental system, which is unique among flies. The larva develops and receives nourishment inside female. The fully grown larva is deposited by the female and rapidly changes into a puparium (McAlpine, 1989; Yeates and Wiegmann, 1999). Glossinids are the only free-living family of hippoboscoids and include tsetse flies, which transmit sleeping sickness in humans (Yeates and Wiegmann, 1999). Glossinids are restricted to the old world tropics. The Hippoboscidae, Streblidae and Nycteribiidae all live continuously on their hosts as adults. All three families are cosmopolitan, but more diverse in the tropics than the temperate zones. Hippoboscids and streblids usually retain their wings and are good fliers, although some species have their wings reduced or absent; nycteribiids are wingless. Hippoboscids are most frequently ectoparasites of birds, but also prey on ungulates and a few other mammals (Maa and Peterson, 1987). Streblids and nycteribiids are united as sister taxa based on several morphological synapomorphies including reduced compound eyes, loss of the ocelli, and the loss of the posterior larval spiricle (McAlpine, 1989). Streblids and nycteribiids also share a lifestyle as ectoparasites on bats and are known collectively as bat flies. The oldest evidence of bats comes from Eocene fossils. Since both streblids and nycteribiids depend exclusively on bats, it may be that the common ancestor of the two bat fly families is not very old, no older than the common ancestor of bats. Since streblids and nycteribiids appear to be so recently derived relative to other fly families, some workers have suggested that they be demoted to subfamily status under a family rank Hippoboscidae (Thompson, pers. comm). Nevertheless, streblids and nycteribiids are quite distinct from each other morphologically. Neither family could be easily mistaken for any other fly taxon except perhaps the hippoboscids, which share a similar adaptive zone. Members of the stereblid subfamily Nycterophiliinae are laterally compressed and superficially flea like in appearance. Members of the Heteropteran family Polyctenidae, which also parasitize bats, were originally described as nycteribiids and resemble bat flies in overall appearance (Schuh and Slater, 1995). Except for the Nycterophiliinae, streblids and nycteribiids tend to be somewhat dorsoventrally flattened. Nycteribiids and streblids are bristly with strong tarsal claws and often have combs of strong setae called ctenidia, all characteristics which help bat flies to cling to their hosts. Bat flies are able to move rapidly over their host and may strongly resist attempts to displace them. Nycteribiids have their head folded back on their thorax at rest; the head is rotated forward for feeding. Nycteribiids are less diverse than streblids with 46 species in two genera known from the Americas (Peterson and Wenzel, 1987). All but four of these species are members of the genus Basilia, which are usually associated with vespertilionid bats. The small genus Hershkovitzia occurs on Thyropterid bats. A total of 148 streblid species in 25 genera have been described from the Americas. They are broadly distributed across bat taxa, absent only from the Thyropteridae (Guerrero, 1997). Although most streblids have well developed wings, wing reduction appears to have occurred numerous times and appears to be associated with life on fruit-eating and fish-eating bats (Wenzel and Peterson, 1987).

Collecting Bias

Most of the material for this project was collected by Marco Tschapka as part of a research program on the ecology of nectar feeding bats (Phylostomidae, Glossophaginae). Bats were collected mostly from the La Selva Biological Station, Costa Rica (Heredia Province). Collections were also made in the adjacent Braulio Carrillo National Park and El Gavilán Ecological Reserve, a 22 ha forest fragment surrounded by banana plantation 6.5 km northeast of La Selva. The plantation and reserve are managed by COBAL (Compania Bananera Atlantico). The bats sampled for bat flies do not approximate the structure of the overall bat population at La Selva. Timm (1994) lists 65 bat species as known from La Selva. Our study examined 37 bat species from La Selva including two species (Micronycteris silvestris and Mesophylla macconnelli) not included in Timm's (1994) list. We also included data from three additional bat species (Anoura cultrata, Anoura geofroyi, and Myotis keaysi) collected in the Braulio Carrillo National Park adjacent to La Selva, but never seen in La Selva itself. Bats from Braulio Carrillo yielded two streblid species not found at La Selva, Anastrebla mattadeni from Anoura cultrata and Anatrichobius scorzai from Myotis keaysi. Bat flies tend to be host specific or to occur on a small number of closely related hosts. Some bat flies occur on distantly related hosts that normally share the same roost site. Several bat species considered common or abundant at La Selva (Timm, 1994) are absent from our investigation, not to mention rare bat species not associated with nectivory. The combination of bat fly host specificity and our collecting bias means that any undersampled or excluded bat species are likely to harbor additional bat fly species.

Assessment of Inventory Completeness

Nonparametric estimators of species richness have become an important tool for estimating inventory completeness. When evaluating such analyses, it is important to keep in mind the sampling universe. In the technical discourse of richness estimation, estimators converge on the number of species available to the method at the time of sampling (Longino and Colwell, 1997). These estimators are driven by the number of rare species. Sexual species in the real world must be common enough to find each other at least in some places at some times. This being the case, richness estimators extrapolate from the number of rare species collected how many species may not have been collected at all: the undersampling bias (Colwell and Coddington, 1994). However, some rare species collected using one set of protocols may in fact be common across some boundary (Longino and Colwell, 1997, Coddington, pers. comm.). This boundary may be temporal (e.g., a species is just beginning or ending its phenologic cycle) or ecological (e.g., a common canopy insect that is rarely sampled by ground-based methods). These are not really undersampling problems since these vagrants may not be part of a breeding population within the sampling universe under study. If rare species in a particular study are really composed primarily of vagrants from across a boundary and not undersampling within the study plot, estimators will give spurious and inflated results. The only way to distinguish rare species due to undersampling from rare vagrant species is to sample a broader the ecological sampling space over a longer period. Using this method, species that are found to be common in one situation but rare in others can be excluded from estimates where they may inflate evidence for undersampling. No conclusions can be drawn about species that remain globally rare because the investigator might always be overlooking some boundary.

We estimated the completeness of our bat fly inventory based on all samples taken from La Selva and Gavilán. No species were collected from Gavilán that were not also collected in La Selva. A total of 42 bat fly species were collected from 326 individual bats. We ran EstimateS version 6 for 1000 replicates of the data with each bat considered a sample. Estimators are divided into abundance (the total number of individuals collected) and incidence based (the number of samples a species is represented in) statistics. The abundance based Chao1 and ACE estimated a total of 46.44 and 45.05 bat fly species, respectively, as the actual richness available to us. The incidence based Chao2 and ICE estimated a total of 50.31 and 49.25 bat fly species, respectively, as the actual richness available to us. The estimator curves do not show the asymptotic behavior that would allow us much confidence in our estimates. Also, the Coleman curve (Cole) indicates that our samples are strongly uneven, which weakens the statistical power of the estimators. These results may not be very surprising because our collecting protocol selected for nectivorous bats, while many potential boundaries remain unexplored. Many of the rare flies were collected only from bats which were also know only from single individuals in this investigation. For bat flies, the bat is the habitat. Bats that were rare in our investigation were disproportionate sources of rare parasites. Future efforts that focus on other bat niches will no doubt discover many additional bat fly species in La Selva.



Literature Cited

Colwell, R.K. and J.A. Coddington. 1994. Estimating terrestrial biodiversity through extrapolation. Philosophical Transactions of the Royal Society, London, 345:101-118.
Fritz, G.N. 1983. Biology and ecology of bat flies (Diptera: Streblidae) on bats in the genus Carollia. Journal of Medical Entomology, 20:1-10.
Guerrero, R. 1997. Catálogo de los Streblidae (Diptera: Pupipara) parásitos de murciálagos (Mammalia: Chiroptera) del nuevo mundo. VII. Lista de especies, hospedadores y paises. Acta Biologica Venezuelica, 19:9-24.
Guimarães, L.R. 1966. The nycteribiid batflies of Panama. In: Ectoparasites of Panama, R.L. Wenzel and V.J. Tipton, eds. Pp. 393-404. Field Museum of Natural History, Chicago.
Longino, J.T. and R.K. Colwell. 1997. Biodiversity assessment using structured inventory: capturing the ant fauna of a tropical rain forest. Ecological Applications, 7:1263-1277.
Maa, T.C. and B.V. Peterson. 1987. Hippoboscidae. In: Manual of Nearctic Diptera (Volume 2), J.F. McAlpine, ed. Pp. 1271-1281. Agriculture Canada, Ottawa.
McAlpine, J.F. 1989. Phylogeny and classification of the Muscomorpha. In: Manual of Nearctic Diptera (Volume 3), J.F. McAlpine, ed. Pp. 1397-1518. Agriculture Canada, Ottawa.
Nowak, R.M. 1994. Walker's Bats of the World. 287 pages. The Johns Hopkins University Press, Baltimore.
Peterson, B.V. and R.L. Wenzel. 1987. Nycteribiidae. In: Manual of Nearctic Diptera (Volume 2), J.F. McAlpine, ed. Pp. 1283-1291. Agriculture Canada, Ottawa.
Schuh, R.T. and J.A. Slater. 1995. Polyctenidae. In: True Bugs of the World (Hemiptera: Heteroptera). Classification and Natural History. Pp. 202-204. Cornell University Press, Ithaca.
Timm, R.M. 1994. Mammals. In: La Selva: Ecology and Natural History of a Neotropical Rain Forest, L.A. McDade, K.S. Bawa, H.A. Hespenheide, and G.S. Hartshorn, eds. Pp. 394-398. University of Chicago Press, Chicago.
Timm, R.M., and R.K. LaVal. 1998. A field key to the bats of Costa Rica. Center of Latin American Studies. Occasional Publication Series, 22:1-30.
Timm, R.M., D.E. Wilson, B.L. Clauson, R.K. LaVal, and C.S. Vaughan. 1989. Mammals of the La Selva-Braulio Carrillo complex, Costa Rica. North American Fauna, 75:1-162.
Wenzel, R.L. and B.V. Peterson. 1987. Streblidae. In: Manual of Nearctic Diptera (Volume 2), J.F. McAlpine, ed. Pp. 1293-1301. Agriculture Canada, Ottawa.
Yeates, D.K. and B.M. Wiegmann. 1999. Congruence and controversy: Toward a higher-level phylogeny of Diptera. Annual Review of Entomology, 44:397-428.

The ALAS Project

La Selva Biological Station in Costa Rica is the site of a major effort to inventory arthropods. The Arthropods of La Selva (ALAS) project was designed to investigate patterns of arthropod diversity in order to address issues of conservation and the development of natural products such as pharmaceuticals and biological control agents. The ALAS project involves intensive collecting efforts using a variety of methods and applies statistical techniques to estimate species richness and the completeness of the inventory for specific taxa. Bat flies are almost never found using standard arthropod collecting methods and are therefore underrepresented in the ALAS inventory. We hope that our investigation of this unusual niche contributes a useful supplement to the collecting efforts of the ALAS team.

Key Works in New World Bat fly Taxonomy

For those wishing to expand their study of bat flies beyond the limits of this web page, the following references contain descriptions and valid nomenclature for many described bat fly species in the Americas.

Guerrero, R. 1993. Catálogo de los Streblidae (Diptera: Pupipara) parásitos de murciálagos (Mammalia: Chiroptera) del nuevo mundo. I. Clave para los géneros y Nycterophiliinae. Acta Biologica Venezuelica, 14:61-75.
Guerrero, R. 1994. Catálogo de los Streblidae (Diptera: Pupipara) parásitos de murciálagos (Mammalia: Chiroptera) del nuevo mundo. II. Los grupos: pallidus, caecus, major, uniformis y longipes del género Trichobius Gervais, 1844. Acta Biologica Venezuelica, 15:1-18.
Guerrero, R. 1994. Catálogo de los Streblidae (Diptera: Pupipara) parásitos de murciálagos (Mammalia: Chiroptera) del nuevo mundo. IV. Trichobiinae con alas desarrolladas. Boletín de Entomología Venezolana, 9:161-192.
Guerrero, R. 1995. Catálogo de los Streblidae (Diptera: Pupipara) parásitos de murciálagos (Mammalia: Chiroptera) del nuevo mundo. III. Los grupos: degesii, dunni y phyllostomae del género Trichobius Gervais, 1844. Acta Biologica Venezuelica, 15:1-27.
Guerrero, R. 1995. Catálogo de los Streblidae (Diptera: Pupipara) parásitos de murciálagos (Mammalia: Chiroptera) del nuevo mundo. V. Trichobiinae con alas reducidas o ausentes y miscelaneos. Boletín de Entomología Venezolana, 10:135-160.
Guerrero, R. 1996. Catálogo de los Streblidae (Diptera: Pupipara) parásitos de murciálagos (Mammalia: Chiroptera) del nuevo mundo. VI. Streblinae. Acta Biologica Venezuelica, 16:1-25.
Guerrero, R. 1997. Catálogo de los Streblidae (Diptera: Pupipara) parásitos de murciálagos (Mammalia: Chiroptera) del nuevo mundo. VII. Lista de especies, hospedadores y paises. Acta Biologica Venezuelica, 19:9-24.
Guerrero, R. 1998. Notes on Neotropical batflies (Diptera, Streblidae). I. The genus Trichobius, with description of two new species and one new subspecies from Venezuela. Acta Parasitologica, 43:86-93.
Guerrero, R. 1998. Notes on Neotropical batflies (Diptera, Streblidae). II. Review of the genus Xenotrichobius. Acta Parasitologica, 43:142-147.
Guimarães, L.R. 1966. The nycteribiid batflies of Panama. In: Ectoparasites of Panama, R.L. Wenzel and V.J. Tipton, eds. Pp. 393-404. Field Museum of Natural History, Chicago.
Guimarães, L.R. 1972. Nycteribiid batflies from Venezuela. Brigham Young University Science Bulletin, Biological Series, 17:1-11.
Guimarães, L.R. 1977. Supplementary note on Venezuelan bat flies (Diptera: Nycteribiidae). Great Basin Naturalist, 37:221-224.
Guimarães, L.R. and A.V. Andretta. 1956. Sinopse dos Nycteribiidae (Diptera) do novo mundo. Arquibos de Zoologia, 10:1-184.
Machado-Allison, C.E. 1963. Un nuevo Nycteribiidae (Diptera) de Venezuela. Acta Biologica Venezuelica, 3:455-459.
Machado-Allison, C.E. 1966. Notas sobre Streblidae (Diptera) de Venezuela I. Las Especies del Genero Pterellipsis Coquillet. Acta Biologica Venezuelica, 5:71-79.
Peterson, B.V. 1971. Notes on the bat flies of Costa Rica. Contributions in Science, 212:1-8..
Peterson, B.V. and L.A. Lacey. 1985. A new species of Hershkovitzia (Diptera: Nycteribiidae) from Brazil, with a key to the described species of the genus. Proceedings of the Entomological Society of Washington, 87:578-582.
Peterson, B.V. and R.L. Wenzel. 1987. Nycteribiidae. In: Manual of Nearctic Diptera (Volume 2), J.F. McAlpine, ed. Pp. 1283-1291. Agriculture Canada, Ottawa.
Wenzel, R.L. 1966. [Descriptions of new genera and species], In: Wenzel, Tipton, and Kiewlecz (q.v.).
Wenzel, R.L. and T.H.G. Aitken. 1966. [Description of Neotrichobius stenopterus n. gen., n. sp.], In: Wenzel, Tipton, and Kiewlecz (q.v.)., pp. 536-540 (Figs. 97-99).
Wenzel, R.L. 1976. The streblid batflies of Venezuela (Diptera: Streblidae). Brigham Young University Science Bulletin, Biological Series, 20:1-177.
Wenzel, R.L. 1984. Two name changes for Neotropical Streblidae (Diptera). Proceedings of the Entomological Society of Washington, 86:647.
Wenzel, R.L. and B.V. Peterson. 1987. Streblidae. In: Manual of Nearctic Diptera (Volume 2), J.F. McAlpine, ed. Pp. 1293-1301. Agriculture Canada, Ottawa.
Wenzel, R.L., V.T. Tipton, and A. Kiewlecz. 1966. The streblid batflies of Panama. In: Ectoparasites of Panama, R.L. Wenzel and V.J. Tipton, eds. Pp. 405-675. Field Museum of Natural History, Chicago.

Acknowledgments

This project grew out of a field problem on the Organization for Tropical Studies "Tropical Biology: An Ecological Approach" course during the winter of 1999. We would like to thank the coordinator of that course, Deedra McClearn, Corine Vriesendorp, and all the OTS students who were such good friends and colleagues. We also thank The Organization for Tropical Studies, the La Selva Biological Station, La Compania Bananera Atlantico, and the Government and people of Costa Rica. Anja Brunet, Bill Cook, Wendy Marussich, Kailen Mooney and Christian Voight helped with mistnetting bats and collecting bat flies. Bob Timm provided constructive criticism, help with bat nomenclature, literature references, and enthusiastic support. F. Christian Thompson provided constructive criticism, experience in fly systematics, and facilitated the hosting of this web page with the USDA. Gustavo Graciolli and Carl Dick provided additional corrections and suggestions. Tom Henry provided information on polyctenid Heteroptera, which also parasitize bats. Don Wilson provided encouragement to embark on a project very different from anything I had done before. Jonathan Coddington, Ingi Agnarsson, and Matjaz Kuntner provided helpful ideas and encouragement. Materials and equipment were supplied by an NSF-PEET grant to Gustavo Hormiga and Jonathan Coddington. Finally, we thank Jack Longino and the ALAS project team for their interest and encouragement.