Archbold Biological Station, Biennial Report 1997-1998

 
Utetheisa ornatrix; adult (upper) and larvae on a Crotolaria seed pod (lower); photos by Tom Eisner


Chemical Ecology

Project Director: Thomas Eisner, Cornell University
Outside Collaborators: Scott Smedley and Athula Attygalle, Cornell University
Graduate Students: Carmen Rossini, Andrés Gonzalez, and Vik Iyengar, Cornell University
Project Assistant: Maria Eisner, Cornell University

[Biennial Contents | Biennial 95-96 |

Thomas Eisner (Cornell Univ.) visited the Station with graduate students, and his research partner, Maria Eisner, several times during 1997–98. A number of projects, all with a chemical-ecological focus, are underway.

     The Ornate Moth. This moth (Utetheisa ornatrix, see photos, this page) is unusual in that it is entirely dependent on certain alkaloids (pyrrolizidine alkaloids) from its food plant (legumes of the genus Crotalaria). Both sexes acquire the chemicals as larvae and retain them through metamorphosis into adulthood. The female invests her chemicals in the eggs, protecting these as a result, but depleting her own alkaloidal supply in the process. To compensate for this loss she receives alkaloids from the male with the sperm package. Individual females may mate with as many as 20 males, thereby acquiring relatively massive amounts of alkaloids during their lifespan. This study provides the first documentation of egg protection by biparental chemical endowment in an animal.

     Phengodid Beetle Larva vs. Millepede. The larva of Phengodes laticollis kills the millipede Floridobolus penneri with an injection of enteric fluid administered with its sharp, sickle-shaped mandibles. The infusion paralyzes the millipede instantly, preventing it from discharging its defensive glands in response. The paralytic agent remains unknown, but is of considerable, perhaps even medicinal, potential (it could be the source of channel-active factors).

     The Chemistry of Walking Sticks. Years ago Eisner’s group characterized the defensive spray of the walking stick Anisomorpha buprestoides. The chemical turned out to be a novel terpene (anisomorphal) of extraordinary irritancy. This work prompted an investigation of the defensive fluid of other walking sticks, resulting in the isolation of another repellent agent (quinoline), not previously known from insects.

     Chemical Prospecting. Eisner’s group continued its search for new chemicals from organisms, with an emphasis on species from the Station. In collaboration with chemists from Cornell the group is looking into substances from plants and insects in hopes of discovering leads to medicinals, agrochemicals, and other substances. Of particular interest is the search for new defensive chemicals from slug eggs.

     "Don’t Say Good Bye." A film by that name, on endangered species, focusing on the photographs of Susan Middleton and David Littschwager, produced by National Geographic Television, includes a segment filmed at the Station dealing with Eisner’s work on "chemical prospecting." Eisner introduced a showing of the film in Washington, D.C., in October 1997, at the AAAS auditorium on the occasion of a "Biodiversity Forum" sponsored by the National Academy of Sciences. The film subsequently received an Emmy award.

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