Current Research Interests
The members of the LSU Disaster Ecology Lab study the ecology of highly disturbed environments using insects as model organisms. When possible, we focus on ant species. Our goal is to create a comprehensive look at these environments and to understand how extreme weather patterns, technological disasters, natural disasters, and pollution levels effect ecosystems, as well as defining keystone species within these ecosystems. My students have examined the ability of ants and other insects to respond to natural disasters such as hurricanes, flooding, fire, and pollution. Our team is also part of a major collaborative effort involving the Gulf of Mexico Research Initiative based out of LUMCON which studies the ecological impacts of the Deepwater Horizon oil spill in the Gulf of Mexico. We also responded to the ecological disasters in South Louisiana caused by flooding associated with hurricanes Katrina, Rita, Gustav, Ike and Isaac by monitoring ant populations in hurricane-affected areas as we study the rate of re-invasion and species turnover.
Ant diversity in Louisiana wetlands is also of interest in our lab. Currently we are testing the subset hypothesis and the ecosystem complexity hypothesis using ants in wetlands as a model system. It turns out that these ecosystems are poorly studied. Using specimens and data from former and current students and my own explorations, a comprehensive book "The Ants of Louisiana" is being written. We previously published the book "The Pest Ants of Louisiana: A guide to Their Identification, Biology, and Control." We investigate basic biology, behavior, and ecology of important ants and discover new-to-the-state or -US species.
There are several ants that are of particular interest to members of my laboratory, including the Elongate Twig ant and the Acrobat ant. The acrobat ant gets its common name from its habit of raising their abdomen over their head and thorax. My students look at effects of flooding, oil, and other stochastic factors that may influence the mortality rates of these ant species.
In the past, we have excavated Texas Leafcutting Ant nests to determine nest structure and how the activities of these ants affect the macro and microstructure of the soil. We have also observed how their activities affect key nutrient levels in the soil. Ground-penetrating radar is being investigated for use in our studies for certain species.
A small population of Comanche harvester ants has been rediscovered in Louisiana. Previously, this species was thought to have been extirpated by fire ants or by the efforts to suppress fire ants. Because harvester ants were essentially eliminated in Louisiana, we are mapping and monitoring this small population. It is interesting to note that this harvester ant population appears confined to highly disturbed, sandy habitats including those cleared by timber harvesting operations and trails maintained for off-road vehicles. We are looking for funding for this project.
The breadth of our program provides members of our lab a unique chance for students to be introduced to many aspects of ecology research. Students that are interested in studying basic aspects of insect ecology are encouraged to apply. Typical projects in my lab focus on disturbance ecology. We currently have an extensive undergrad program with nine students working in the lab. Mentoring, field experience, and moving towards career goals - from concepts to publication - are among the benefits of working in our lab.
Snapshots:
The Pest Ants of Louisiana: a guide to their identification, biology, and control contains information on fifteen species of ants that occur in our state. A dichotomous key and numerous photographs help readers determine which species of ant is present around their home and garden.
The red imported fire ant, Solenopsis invicta Buren, was introduced into the US from South America in the 1930’s. The species can now be found in disturbed habitats in both rural and urban environments throughout the Southeast. The red imported fire ant is a highly invasive, pest species that causes severe economic and ecological damage and is a serious health concern for people and pets.
Excavation of Texas leafcutting ant, Atta texana (Buckley), nests require a team of researchers to thoroughly investigate colony activity. Pictured here (starting at top left) are Shawn Dash (former MS student), Michael Seymour (research associate), Andy Cline (former PhD student), Caren Carney (former research associate), Dr. Linda Hooper-Bùi (head of RIFA lab), (bottom row) Jennifer Fleming (former student worker), Katie O’Brien (former MS student), and Kristin Prejean (former student worker). A team of graduate students from Dartmouth College (not pictured) graciously provided valuable assistance on this particular dig.
Because Texas leafcutting ant, Atta texana (Buckley), nests may extend to depths of 3 meters or more below ground, heavy machinery is required to rapidly access the nest’s underground chambers.
An alate Texas leafcutting ant, Atta texana (Buckley), such as the male pictured here, may have hitchhikers riding on his body as he leaves the nest for mating flights. These small symbiotic roaches, Attaphila fungicola Wheeler, are phoretic on male and female reproductive leafcutting ants. Except during these ant mating flights, this little roach is only found deep within the fungus gardens of leafcutting ant nests
The large major worker, or soldier, Texas leafcutting ant, Atta texana (Buckley), is a formidable nest defender. Covered in stout, sharp spines and equipped with scissor-like mandibles, leafcutting ants make quick work of exposed (and frequently unexposed!) flesh on the human researchers. When inside a newly exposed nest, literally thousands of ants may come out to “greet” the visiting scientist!
The Texas leafcutting ant, Atta texana (Buckley), which occurs only in Texas and Louisiana, is a fungus-growing ant. Rather than eat the foliage they gather, the ants use the leaves as substrate upon which a fungus grows. The fungus garden, shown here in situ (about 2.5 meters below the surface), serves as the food resource for the colony.
Long thought extirpated from LA, a small population of the Comanche harvester ant, Pogonomyrmex comanche Wheeler, was recently rediscovered in north LA. These large ants have psammophores, a beard-like growth in which the ants pack small soil particles from nest excavation or, perhaps, food particles, as has been shown in laboratory studies.
In addition to the recent rediscovery of several Comanche harvester ant, Pogonomyrmex comanche Wheeler, colonies in north LA, newly-mated queens were found digging new nests. Queen harvester ants are readily distinguished from workers by the larger size of queens and by the robust thorax that allows for wing musculature (wings are shed after mating).
In his MS study at LSU, Michael Seymour discovered that with concentrated effort, red imported fire ants, Solenopsis invicta Buren, create large holes in Northern Bobwhite, Colinus virginianus, eggshells allowing for entry and exit of several workers at a time. The arrow points to a third egg that is in the process of being breached; note the missing bits of eggshell but intact membrane of the egg.
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