DNA barcodes affirm that 16 species of apparently generalist tropical parasitoid flies (Diptera, Tachinidae) are not all generalists
- *Biodiversity Institute of Ontario, University of Guelph, Guelph, ON, Canada N1G 2W1;
- ‡Diptera Unit, Canadian National Collection of Insects, Agriculture and Agri-Food Canada, Ottawa, ON, Canada K1A 0C6; and
- §Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018
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Contributed by Daniel H. Janzen, December 30, 2006 (received for review December 26, 2006)
Abstract
Many species of tachinid flies are viewed as generalist parasitoids because what is apparently a single species of fly has been reared from many species of caterpillars. However, an ongoing inventory of the tachinid flies parasitizing thousands of species of caterpillars in Area de Conservación Guanacaste, northwestern Costa Rica, has encountered >400 species of specialist tachinids with only a few generalists. We DNA-barcoded 2,134 flies belonging to what appeared to be the 16 most generalist of the reared tachinid morphospecies and encountered 73 mitochondrial lineages separated by an average of 4% sequence divergence. These lineages are supported by collateral ecological information and, where tested, by independent nuclear markers (28S and ITS1), and we therefore view these lineages as provisional species. Each of the 16 apparently generalist species dissolved into one of four patterns: (i) a single generalist species, (ii) a pair of morphologically cryptic generalist species, (iii) a complex of specialist species plus a generalist, or (iv) a complex of specialists with no remaining generalist. In sum, there remained 9 generalist species among the 73 mitochondrial lineages we analyzed, demonstrating that a generalist lifestyle is possible for a tropical caterpillar parasitoid fly. These results reinforce the emerging suspicion that estimates of global species richness are likely underestimates for parasitoids (which may constitute as much as 20% of all animal life) and that the strategy of being a tropical generalist parasitic fly may be yet more unusual than has been envisioned for tachinids.
Footnotes
- †To whom correspondence may be addressed. E-mail: salex{at}uoguelph.ca or djanzen{at}sas.upenn.edu
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Author contributions: M.A.S., D.H.J., W.H., and P.D.N.H. designed research; M.A.S., D.M.W., D.H.J., and W.H. performed research; M.A.S., D.H.J., and W.H. analyzed data; and M.A.S., D.H.J., W.H., and P.D.N.H. wrote the paper.
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The authors declare no conflict of interest.
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Data deposition: The sequences reported in this paper have been deposited in the GenBank database (CO1: accession nos. EF180450–EF182583; 28S and ITS1: accession nos. EF183546–EF184019 and EF189688–EF189703 and two representative sequences of Chetogena scutellarisDHJ01 Wolbachia, accession nos. EF192042 and EF192043).
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See Commentary on page 4775.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0700050104/DC1.
- Abbreviations:
- ACG,
- Area de Conservación Guanacaste, Costa Rica;
- CO1,
- cytochrome c oxidase 1;
- NJ,
- neighbor-joining.
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Freely available online through the PNAS open access option.
- © 2007 by The National Academy of Sciences of the USA
