Research

Reproductive Ecology of Rare Plants

When a species becomes very rare, it can be hard for its members to find one another to mate; in the case of plants, rare species may fail to attract the pollinators that move their gametes. My current work addresses the reproductive ecology of three species of federally endangered plants on Fort Bragg in the North Carolina sandhills. For each plant species, this research will identify its pollinators, assess its population genetic structure, and where possible, measure pollen-mediated gene flow between populations or species. In collaboration with Clyde Sorenson and the lab of Becky Irwin, I am also involved with research on the pollination and evolutionary ecology of Venus flytrap–a carnivorous plant native only to North and South Carolina.

Insects, Urbanization, and Climate Change

Cities are warmer than the surrounding landscape, causing some insects to grow, reproduce, or develop faster than they do outside the city. Elsa’s current work in the lab of Steve Frank looks at how urban warming alters the abundance and ecology of insects that live on and around street trees. For example, gloomy scale insects (the little bumps covering the branch in the photo) are most abundant in the hottest urban sites around Raleigh, NC. Understanding how plant-insect interactions work in cities today may give a preview of how the surrounding forests will also change with global warming.

Ant Gardens

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. (Click here to go to video of the ants picking up the seeds.)

What keeps these particular ants and seeds together? At least some of the ant-garden seeds attract only gardening ants, while other ants seem to dislike the seeds. The seeds have a strong smell, some components of which attract the gardening ants from a distance and help them find the seeds. Then additional chemical cues on the seeds prompt the ants to pick up the seeds and carry them to their nests.

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.

It turns out the ants ignore the caterpillars because the aphid chemistry rubs off on the caterpillars, fooling the ants into thinking that the predators are just extra-large aphids.

Publications

Terando, A. J., E. Youngsteadt, E. K. Meineke, and S. G. Prado. In press. Ad hoc instrumentation methods in ecological studies produce highly biased temperature measurements. Ecology and Evolution.

Savage, A. M., E. Youngsteadt, A. F. Ernst, S. Anderson Powers*, R. R. Dunn, and S. D. Frank. In press. Homogenizing an urban habitat mosaic: Arthropod diversity declines in NYC parks after Super Storm Sandy. Ecological Applications.

Hamblin, A. L.†, E. Youngsteadt†, M. M. López-Uribe, and S. D. Frank. 2017. Physiological thermal limits predict differential responses of bees to urban heat-island effects. Biology Letters 13:20170125. †Co-first authors. link pdf

López-Uribe, M. M., R. H. Appler, E. Youngsteadt, R. R. Dunn, S. D. Frank, and D. R. Tarpy. 2017. Higher immunocompetence is associated with higher genetic diversity in feral honey bee colonies (Apis mellifera). Conservation Genetics 18:659-666 doi: 10.1007/s10592-017-0942-x. link pdf

Youngsteadt, E., Ernst, A. F., Dunn, R. R., and Frank, S. D. 2016. Responses of arthropod populations to warming depend on latitude: evidence from urban heat islands. Global Change Biology 23:1436-1447. link pdf

Meineke, E. K., Youngsteadt, E., Dunn, R. R., and Frank, S. D. 2016. Urban warming reduces above-ground carbon storage. Proceedings B 283:20161574. link pdf

Youngsteadt, E., Moylett, H., López-Uribe, M., and Hamblin, A. 2016. T. B. Mitchell: the man behind The Bees of the Eastern United States. American Entomologist 62(3):157-162. link pdf

Dale, A. G., Youngsteadt, E., and Frank, S. D. 2016. Forecasting the effects of heat and pests on urban trees: impervious surface thresholds and the ‘Pace to Plant’ technique. Arboriculture and Urban Forestry 42(3):181-191. link pdf

Reese, A., Savage, A. M., Youngsteadt, E., McGuire, K., Koling, A., Watkins, O., Frank, S. D., and Dunn, R. R. 2016. Urban stress is associated with variation in microbial species composition—but not richness—in Manhattan. The ISME Journal 10:751-760. link pdf

Youngsteadt, E., Appler, R.H., López-Uribe, M. M., Tarpy, D. R., and Frank, S. D.. 2015. Urbanization increases pathogen pressure on feral and managed honey bees. PLoS ONE 10: e0142031. link

Youngsteadt, E., Henderson, R. C., Savage, A. M., Ernst, A. F., Dunn, R. R., and Frank, S. D. 2015. Habitat and species identity, not diversity, predict the extent of refuse consumption by urban arthropods. Global Change Biology. link pdf

Savage, A. M., Hackett, B., Guénard, B., Youngsteadt, E., and Dunn, R. R. 2015. Fine-scale heterogeneity across Manhattan’s urban habitat mosaic is associated with variation in ant composition and richness. Insect Conservation and Diversity 8:216–228. link pdf

Youngsteadt, E., Dale, A. G., Terando, A. J., Dunn, R. R., and Frank, S. D. 2015. Do cities simulate climate change? A comparison of herbivore response to urban and global warming. Global Change Biology 21:97-105. link pdf

Youngsteadt, E., Guerra, P. and Schal, C. 2010. Divergent chemical cues elicit seed collecting by ants in an obligate multi-species mutualism in lowland Amazonia. PLoS ONE, 5:e15822. link

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 pdf link

Booth, W., Youngsteadt, E., Schal, C. and Vargo, E. 2009. Characterization of 8 polymorphic microsatellite loci in the neotropical ant-garden ant, Camponotus femoratus. Conservation Genetics, 10:1401-1403. pdf link

Booth, W., Youngsteadt, E., Schal, C. and Vargo, E. 2009. Polymorphic microsatellite loci for the ant-garden ant, Crematogaster levior (Forel). Conservation Genetics, 10:639-641. pdf link

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

Dissertation

Neotropical Ant-Gardens: Behavioral and Chemical Ecology of an Obligate Ant-Plant Mutualism. link

In the News

The New York Times “Bugs in Manhattan compete with rats for food refuse” December 2, 2014

CBC Quirks and Quarks “Ants perform street cleaner role on Broadway” December 6, 2014

Science “Bugs in Manhattan eat thousands of kilograms of trash each year” December 2, 2014

Newsweek “Want to see the earth after global warming? Move to the City” August 2014

Greenwire “Oak, maple pests thrive in warmer weather — study” August 2014

Entomology Today “Museum specimens show how scale insects will respond to climate change August 2014

NCSU News “Museum specimens, modern cities show how an insect pest will respond to climate change” August 2014

NC State University Bulletin “Researchers regroup post Sandy” February 2013

Miller McCune “Curiouser and Curiouser” podcast February 2011

BioScience March 2008

NCSU News January 2008

ScienceNOW (“Smelly seeds”) January 2008