Directory Emeritus, Professor of the Graduate School
The principal theme of my research has been to discover and correlate biological features with traditional morphological evidence in the development of biosystematic relationships of Microlepidoptera (small moths).
My approach can be categorized along four lines:
- systematics studies of particular taxa
- comparative biology oriented along hostplant or ecological roles (e.g., yucca moths, fungus feeders, borers of woody composites, leaf miners, sand dune associates)
- a broad spectrum larval rearing program
- faunal inventory
The major taxa in which I have concentrated efforts are New World Tortricinae (Tortricoidea) and Ethmiinae (Gelechioidea). I have carried out biosystematic studies of these and a variety of other moths, sometimes in response to requests from other biologists (e.g. our current studies of Choristoneura in cooperation with forest entomologists) or as taxonomic problems became evident during biological and faunal studies.
Our rearing program is the most extensive in the history of the study of New World Microlepidoptera. During the past 35 years my students and I have processed more than 13,000 collections of larval or live adult Lepidoptera. Resulting data encompass more than 1,000 species of moths, through rearing either field-collected larvae or those emerging from eggs deposited by females in confinement. This total includes more than 60% of an estimated 1,500 species of Microlepidoptera occurring in California. We have summarized the collection data, larval food, and other data in a d-Base III+ program.
Ongoing Research Projects
Classification of Nearctic and Neotropical Tortricinae. I have conducted long term studies of the Nearctic fauna, published a framework for the classification of Neotropical genera, species level treatments of several of the genera, and checklists of the North American and Neotropical faunas. Our studies on relationships among the Neotropical genera have emphasized the Tribes Archipini, Atteriini, Sparganothidini, and Euliini; and in collaboration with Prof. Sperling, we are beginning a NSF sponsored graduate training project emphasizing systematics of these moths.
Faunal inventories. In an era when there is considerable interest in biodiversity and extinctions, it is a paradox that we do not have a complete list of the Lepidoptera species, including an estimate of the undescribed species, for any state, county, or locality in North America. I have initiated inventories at several localities in California; the most comprehensive of these are the faunas of Santa Cruz Island, Walnut Creek, and Big Creek, Monterey Co. During the past several years I have devoted the largest portion of my time to the last. My students and I have made numerous trips to the site, having sampled on about 200 dates, spanning all months. We have processed nearly 300 blacklight samples and more than 1,300 larval collections, and these represent about 340 species (37% of the known fauna of 910+ species). As a means of comparison to Neotropical faunal inventory, I am a collaborator on an NSF-sponsored project through OTS in which we are sampling the biodiversity of selected arthropods at the La Selva Biological Station in Costa Rica.
The ultimate goals of these biodiversity studies are to: a) develop comprehensive local inventories of the species, which can serve as a baseline for comparison of other Nearctic and tropical faunal inventories; b) provide means for estimating species richness in North Temperate Zone lepidopterous faunas by projecting from species accumulation rates and from floral diversity, which often is documented well ahead of that of insects; c) analysis of larval host plant relationships of the Lepidoptera communities.
Powell, J. A. 1991. A review of Lithariapteryx (Heliodinidae), with description of an elegant new species from coastal sand dunes in California. J. Lepid. Soc. 45(2):89-104.
Brown, J. W. & J. A. Powell. 1991. Systematics of the Chrysoxena Group of genera (Lepidoptera:Tortricidae: Euliini.) U. Calif. Publ. Entomol., Vol. 111:1-129.
Powell, J. A. 1992. Interrelationships of yuccas and yucca moths. Trends in Ecol. & Evol. 7(l):10-15.
Powell, J. A. 1992. Recent colonization of the San Francisco Bay Area, California, by exotic moths (Lepidoptera: Tineoidea, Gelechioidea, Tortricoidea, Pyraloidea). Pan-Pacific Entomol. 68(2):105-121.
Powell, J. A. & D. L. Wagner. 1993. The Microlepidoptera fauna of Santa Cruz Island is less depauperate than that of butterflies and larger moths. In “Third California Islands Symposium, Recent advances in research on the California Islands”, Santa Barbara Nat. Hist. Mus., pp. 189-198.
Powell, J. A. 1994.Biogeography of Lepidoptera on the California Channel Islands. In “The Fourth California Islands Symposium: Update on the status of resources; Sta. Barbara Mus. Nat. Hist., Santa Barbara; pp. 449-464.
Powell, J. A. 1996. Biosystematic studies of conifer-feeding Choristoneura in the western United States (Lepidoptera:Tortricidae). J. A. De Benedictis et al. (1995) U. Calif. Publ. Entomol.