James T. Cronin

James  T.  Cronin

George C. Kent Professorship in Life Sciences #3
SEE Division

PhD: Florida State University, 1991
Phone: 225-578-7218
Lab Phone: 225-578-7221

E-mail: jcronin@lsu.edu
Office: A306 Life Sciences Annex
Lab: A359/A361 Life Sciences Annex
Website:  Cronin Website

Area of Interest

My research interests center on the ecology and evolution of plant-herbivore-natural enemy interactions. This stems from both an applied interest in the biological control of plant pests by natural enemies and a theoretical interest in the behavior, population dynamics and persistence of species comprising ecological communities. In my research program, I advocate a spatial approach to understanding these trophic interactions.

My current research interests focus on four broad areas.

1. Biogeography of plant invasions. I am particularly interested in the factors that influence invasion success over broad-geographic and temporal spatial scales. My research focuses on the invasive grass, Phragmites australis. We have explored the effects of latitude, natural enemies (i.e., herbivores, pathogens), higher trophic levels, soil microorganisms, plant genetics (ploidy, genome size, and genotypic variation), plant defensive chemistry, and climate change on invasion success and interactions with other members of the recipient community. More details about this research can be found by clicking here.

2. Causes for predator-prey population cycles. Understanding the mechanisms promoting stability of predator-prey interactions has been a longstanding interest of mine. I have been studying a model system involving the cowpea weevil (Callosobruchus maculatus) and its parasitoid (Anisopteromalus calandrae) that is known to exhibit outbreak cycles in the laboratory. My colleagues and I have been performing experiments to test the underlying causes of these outbreak cycles. Specifically, we are interested in whether changes in the age structure of the prey (specifically, the duration and variability of prey development time) affect predator-prey population cycles and stability (for more details, click here).

3. Density-dependent dispersal and population dynamics. Dispersal can have major consequences for individual fitness, population dynamics, and species’ distributions. Understanding the causes and consequences of dispersal at both the patch and landscape levels is vital for population management and conservation. The paradigmatic view of dispersal is that it becomes more frequent as density increases. However, the pattern of density-dependent dispersal can take many forms. My colleagues and I are using mathematical models and experiments to assess how different forms of dispersal can affect population dynamics and stability of competing species and predators and their prey. For more details about this research, click here.

4. Role of habitat fragmentation and landscape heterogeneity on predator-prey spatial and temporal population dynamics. My primary study system includes the planthopper Prokelisia crocea and its egg parasitoid Anagrus columbi that coexist among discrete patches of prairie cordgrass in the tallgrass prairies of North Dakota. My students and I have experimentally examined how cordgrass patch and landscape structure influenced host and parasitoid foraging and dispersal behavior, extinction risk, and population dynamics. My colleagues and I have also developed behavior-based landscape-level models to understand the effects of habitat heterogeneity on the population dynamics of interacting species. Offshoots of this work involved the effects of invasive exotic plants on the population dynamics of native fauna, and the use of stepping stones and corridors in promoting connectivity among habitat fragments. More details on this research project can be found by clicking here.

5. Fire history and oak-cynipid community structure. Along with my old friend and former postdoc advisor, Warren Abrahamson, we are studying the effects of time-since-fire on cynipid gall wasp community structure. Our work is being conducted at Archbold Biological Station in central Florida. More details on this research project can be found by clicking here

6. Roseau cane (Phragmites australis) Dieback in the Mississippi River Delta. This is a multi-departmental collaboration among scientists at LSU that focuses on the widespread die-offs of Roseau cane (Phragmites australis) in the Mississippi River Delta. Our team is exploring the effects of multiple stressors (e.g., invasive scale insects, soil toxins, plant pathogens and climate change) on the health of this plant species. More details on this research project can be found by clicking here.

I welcome inquiries from prospective graduate students interested in research opportunities in my laboratory.  Possible areas of study include all aspects of plant-insect interactions, insect predator-prey interactions, spatial and landscape ecology, invasion biology, and conservation biology.

Selected Publications

For a complete list and reprints, click here

Harms, N. E., J. T. Cronin and J. Gaskin. 2021. Increased ploidy of Butomus umbellatus L. in introduced populations is not associated with higher phenotypic plasticity to N and P. AoB Plants 13: https//doi.org/10.1093/aobpla/plab1045.

Cronin, J. T., J. Goddard II, A. Muthunayake and R. Shivaji. 2020. Modeling the effects of trait-mediated dispersal on coexistence of mutualists. Mathematical Biosciences and Engineering 17: 7838-7861.

Cronin, J. T., J. Johnston and R. Diaz. 2020. Multiple potential stressors and dieback of Phragmites australis in the Mississippi River Delta, U.S.A. Wetlands 40: 2247-2261.

Harms, N. E., J. T. Cronin, R. Diaz and R. Winston. 2020. A review of causes and consequences of geographical variability in weed biological control success. Biological Control https://doi.org/10.1016/j.biocontrol.2020.104398.

Croy J. R.*, W. J. Allen, L. A. Meyerson and J. T. Cronin. 2020. Lineage and latitudinal variation in Phragmites australis tolerance to herbivory: Implications for invasion success. Oikos 129: 1341-1357. 

Allen, W. J., A. E. DeVries, N. J. Bologna, W. A. Bickford, K. P. Kowalski, L. A. Meyerson and J. T. Cronin. 2020. Intraspecific and biogeographic variation in foliar fungi communities and pathogen damage: implications for invasion success. Global Ecology and Biogeography 29: 1199-1211.

Meyerson, L. A., P. Pyšek, M. Lučanová, S. Wigginton, C.-T. Tran and J. T. Cronin. 2020. Plant genome size influences stress tolerance of invasive and native plants via plasticity. Ecosphere 11: Article e03145.

Cronin, J. T., G. Melika and W. G. Abrahamson. 2020. Time-since fire and cynipid gall wasp assemblages on oaks. Biodiversity and Conservation 29: 1177-1203.

Harman, R. R., J. Goddard II, R. Shivaji and J. T. Cronin. 2020. Diverse forms of density-dependent emigration and their population-dynamic consequences. American Naturalist 195: 851-867.

Cronin, J. T., N. Fonseka, J. Goddard, J. Leonard and R. Shivaji. 2019. Modeling the effects of density dependent emigration, weak Allee effects, and matrix hostility on patch-level population persistence. Mathematical Biosciences and Engineering 17: 1718-1742.

Cronin, J. T., J. Goddard II and R. Shivaji. 2019. Effects of patch matrix and individual movement response on population persistence at the patch level. Bulletin of Mathematical Biology doi.org/10.1007/s11538-019-00634-9.

Harms, N. and J. T. Cronin. 2019. Variability in weed biological control: effects of foliar nitrogen on larval development and dispersal of the alligatorweed flea beetle, Agasicles hygrophila. Biocontrol 135: 16-22.

Allen, W. J., L. A. Meyerson, A. J. Flick and J. T. Cronin. 2018. Intraspecific variation in indirect plant-soil feedbacks influences a wetland plant invasion. Ecology 99: 1430-1440.

Bowen, J. L., P. J. Kearns, J. E. K. Byrnes, S. Wigginton, W. J. Allen, M. Greenwood, K. Tran, J. Yu, J. T. Cronin and L. A. Meyerson. 2017. Lineage overwhelms environmental conditions in determining rhizosphere bacterial community structure in a cosmopolitan invasive plant. Nature Communications 8: 433 (10.1038/s41467-017-00626-0).

Allen, W. P., L. A. Meyerson, D. Cummings*, J. Anderson*, G. P. Bhattarai, and J. T. Cronin. 2017. Biogeography of a plant invasion: drivers of latitudinal variation in local enemy release. Global Ecology and Biogeography 26: 435-446. 

Cronin, J. T., J. D. Reeve, D. Xu, M. Xiao and H. N. Stevens. 2016. Variable prey development time suppresses predator-prey cycles and enhances stability. Ecology Letters 19: 318-327.

Cronin, J. T., L. A. Meyerson, G. Bhattarai and W. Allen. 2015. Biogeography of a plant invasion: plant-herbivore interactions. Ecology 96: 1115-1127.

Bezemer, T. M, J. A. Harvey, and J. T. Cronin. 2014. The response of native insect communities to invasive plants. Annual Review of Entomology 59: 119-141.


Ana Salgado-Maldonado, postdoctoral associate, email

Andrea Glassmire, postdoctoral associate, email

Aaron Krivchenia, graduate student, email

Joseph Johnston, graduate student, email

Herie Lee, research associate, email