| Elsa
Youngsteadt Science Writer |
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| In addition to science writing, Elsa has
done a bit of scientific
research herself. She is fascinated by mutualisms-- mutually beneficial
or cooperative interactions between different species-- and the
communication signals that facilitate these interactions. Ants are
her favorite mutualists, and they got involved in both her masters and
Ph.D. research. Carnivorous caterpillars At the University of Wisconsin-Milwaukee, Elsa studied North America's only predatory butterfly caterpillar, Feniseca tarquinius. This caterpillar eats aphids, small immobile insects that excrete a sweet syrup that ants like to eat. The ants usually defend the aphids in exchange for this honeydew. But they leave Feniseca caterpillars alone. The reason? Aphid surface chemistry rubs off on the caterpillars; ants seem to trust their chemical senses better than their eyes, so they accept the predators as extra-large aphids. |
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Horticultural ants Later, at North Carolina State University, Elsa got into a different mutualism, this time between ants and plants rather than ants and aphids. Throughout the Amazon, a few species of ants build their nests in trees and embed seeds of specific plants in the nest walls. The plants grow, forming conspicuous hanging gardens. The plants don't grow anywhere else, and if the ants don't have the plants, their nests fall apart during the rainy season. What keeps these particular ants and these particular seeds together in a jungle inhabited by thousands of species? At least some of the ant-garden seed species attract only gardening ants, while other ants seem to dislike the seeds. A combination of volatile compounds on the seeds give them a strong smell, which attracts the gardening ants from a distance and helps them find the seeds. Then additional chemical cues on the seeds prompt the gardening ants to pick up the seeds and carry them to their nests. |
| Publications
Youngsteadt,
E.,
Alvarez, J., Osborne, J., and Schal, C., 2009. Species specific
seed dispersal
in an
obligate ant-plant mutualism. PLoS ONE, 4:e4335. link Booth, W.,
Youngsteadt,
E., Schal, C. And Vargo, E. 2008. Characterization of 8 polymorphic
microsatellite loci in
the neotropical ant-garden ant, Camponotus
femoratus. Conservation Genetics, published
online 28 August, 2008. pdf Booth, W.,
Youngsteadt, E., Schal, C. And Vargo, E. 2008. Polymorphic
microsatellite loci for
the ant-garden ant, Crematogaster
levior (Forel). Conservation Genetics, published
online 25 April, 2008. pdf Youngsteadt,
E., Nojima, S., Häberlein, C.,Schulz,
S. and Schal, C. 2008. Seed odor mediates an obligate ant-plant
mutualism in
Amazonian rainforest. Proceedings of the National Academy
of Sciences, 105: 4571-4575. link Youngsteadt,
E., Fan,
Y., Stay, B., and Schal, C., 2005.
Cuticular hydrocarbon synthesis and its maternal provisioning to
embryos
in the viviparous cockroach Diploptera
punctata. Journal of Insect Physiology, 51: 803-809. pdf Youngsteadt, E. and DeVries, P. J., 2005. The effects of ants on the entomophagous butterfly caterpillar Feniseca tarquinius and the putative role of chemical camouflage in the Feniseca-ant interaction. Journal of Chemical Ecology, 31: 2091-2109. pdf In the news BioScience March, 2008 NCSU News Jan 30, 2008 ScienceNOW ("Smelly seeds") Jan, 2008 Dissertation Neotropical Ant-Gardens: Behavioral and Chemical Ecology of an Obligate Ant-Plant Mutualism. link |