John T. Lill

John T. Lill

Title:
Associate Professor of Biology
Office:
Lisner Hall 415
Phone: 202-994-6989
Email:
lillj@gwu.edu

Background

Plant-insect interactions, insect ecology and evolution.

Current Research

My research interests are focused on the ecology and evolution of plant-herbivore interactions. More specifically, I am interested in understanding the joint impacts of host plant traits and natural enemies (insect predators and parasitoids) on insect herbivore life history traits, population dynamics, and host plant ranges. Most of the abundant literature in this field has focused on single trophic level interactions (i.e., between insect herbivores and their host plants or between insect herbivores and their natural enemies) and has failed to adequately address the complex multi-trophic level interactions thought to characterize both natural and agricultural systems.


Life History Evolution

I am interested in how seasonal changes in host plant quality and the risk of attack from natural enemies jointly select on various life history traits in Lepidoptera. Many species of Lepidoptera exhibit wide variation in the timing of critical interrelated life cycle events (egg hatch, larval feeding, diapause), yet the genetic basis of and the fitness consequences for individual variation in these traits are poorly understood. This information is essential to understanding the potential role of natural selection in shaping insect life histories. Past research in this area revealed variation in both the direction and magnitude of phenotypic selection on the timing of larval development and on size at metamorphosis.


Arthropod Community Ecology

I have several project underway that have a common goal: to understand the role that indirect interactions play in structuring the arthropod communities associated with different tree species.

Leaf shelters. In my collaborative research with Dr. Robert Marquis (University of Missouri-St. Louis), we demonstrated that leaf-tying caterpillars on white oak (Quercus alba L.) act as physical ecosystem engineers by constructing habitats (leaf shelters) that are subsequently colonized by an array of other leaf-tiers, non-tying herbivores, scavengers, and predators. The results of this study indicated that both the abundance and composition of the oak arthropod fauna changed dramatically when leaf shelters were experimentally removed. We are also examining the effects of shelter-building on seasonal patterns of leaf damage and its effect on tree growth and survival. Other collaborative research on shelter-building (with Dr. Clive Jones, Institute of Ecosystem Studies) is aimed at characterizing potential scale-dependent effects of engineering on species richness in red oak (Quercus rubra).

Induced responses. Early-season damage has been shown to induce changes in various plant traits (chemistry, morphology, phenology). I am interested in how early-season defoliation by eastern tent caterpillars (Malacosoma americanum) influences the abundance and composition of leaf-chewing herbivores occupying black cherry trees (Prunus serotina) later in the season.

Natural enemy-mediated effects. Natural enemies also have the potential to mediate interactions among herbivores through indirect competition for enemy-free space. I am examining this topic using a large data set of plant-herbivore-parasitoid interactions collected from Canadian forest trees (collaboratively with Drs. Robert Ricklefs and Robert Marquis, Univeristy of Missouri-St. Louis). Our early results indicate that for many generalist caterpillars, choice of host plant has a significant effect on the risk of mortality from parasitism. I am also engaged in field experiments that directly test these ideas and have begun collecting data to examine patterns of host plant-specific parasitism for a variety of generalist herbivores, including fall webworm (Hyphantria cunea), which is perhaps the most polyphagous forest caterpillar on record.


Lab Members

Elisha Sigmon
Mariana Abarca
Erik Howard

Undergrads:

Michelle Sliwinski
Robert Oppenheimer

Education

B.S., Biology, University of Maryland, 1990
M.S., Conservation Biology, University of Maryland, 1992
Ph.D., Biology, University of Missouri St. Louis, 1999

Publications

Forkner, R. E., R. J. Marquis, J. T. Lill, and J. Le Corff. 2008. Timing is everything? Phenological synchrony and population variability in leaf-chewing herbivores of QuercusEcological Entomology 33: 276-285.

Lill, J. T. 2008. Caterpillar-host plant relationships recorded from Plummers Island. Proceedings of the Biological Society of Washington 15: 77-81. 

Dyer, L. A. M.S. Singer, J.T. Lill, J.O. Stireman III, G.L. Gentry, R.J. Marquis, R.E. Ricklefs, H.F. Greeney, D.L. Wagner, H.C. Morais, I.R. Diniz, T.A. Kursar, and P.D. Coley. 2007. Host specificity of Lepidoptera in tropical and temperate forestsNature 448: 696-699. 

Lill, J. T., and R. J. Marquis. 2007. Microhabitat manipulation: ecosystem engineering by shelter-building insects. In: Cuddington, K. M. D., Byers, J. E., A. Hastings, and W. G. Wilson, (eds.), Ecosystem Engineers: Concepts, Theory, and Applications in Ecology, Elsevier (in press).

Lill, J. T. 2007. Caterpillar-host plant relationships recorded from Plummers Island. Proceedings of the Biological Society of Washington (in press).

Lill, J. T., R. J. Marquis, M. A. Walker, and L. Peterson. 2007. Ecological consequences of shelter-sharing by leaf-tying caterpillars. Entomologia Experimentalis et Applicata.

Marquis, R. J., and J. T. Lill. 2007. Effects of herbivores as physical ecosystem engineers on plant-based trophic interaction webs. Pp. 246-274 in: Ohgushi, T., Craig, T. and Price, P. W. (eds.), Ecological Communities: Plant Mediation in Indirect Interaction Webs, Cambridge University Press.

Lill, J. T., R. J. Marquis, R. E. Forkner, J. Le Corff, and N. A. Barber. 2006. Leaf pubescence affects distribution and abundance of generalist slug caterpillars (Lepidoptera: Limacodidae)Environmental Entomology 35: 797-806.

Forkner, R. E., R. J. Marquis, J. T. Lill, and J. Le Corff. 2006. Impacts of alternative timber harvest practices on leaf-chewing herbivores of oakConservation Biology 20: 429-440.

Stireman, J. O., III, L. A. Dyer, D. H. Janzen, M. S. Singer, J. T. Lill, R. J. Marquis, R. E. Ricklefs, G. L. Gentry, W. Hallwachs, P. D. Coley, J. A. Barone, H. F. Greeney, H. Connahs, P. Barbosa, H. C. Morais, and I. R. Diniz. 2005. Climatic unpredictability and parasitism of caterpillars: implications of global warmingProceedings of the National Academy of Sciences 102: 17384-17387.

Forkner, R. E., R. J. Marquis, and J. T. Lill. 2004. Feeny revisited: condensed tannins as anti-herbivore defenses in leaf-chewing herbivore communities of QuercusEcological Entomology 29: 174-187.

Lill, J. T., and R. J. Marquis. 2004. Leaf ties as colonization sites for forest arthropodsEcological Entomology 29: 1-9.

Lill, J. T. 2004. Seasonal dynamics of leaf-tying caterpillars on white oak. Journal of the Lepidopterists’ Society 58: 1-6.

Lill, J. T., and R. J. Marquis. 2003. Ecosystem engineering by caterpillars increases insect herbivore diversity on white oakEcology 84: 682-690.

Marquis, R. J., J. T. Lill, and A. Piccinni. 2002. Effect of plant architecture on colonization and damage by leaftying caterpillars of Quercus albaOikos 99: 531-537.

Lill, J. T., R. J. Marquis, and R. E. Ricklefs. 2002. Host plants influence parasitism of forest caterpillarsNature 417: 170-173.

Marquis, R. J., R. Forkner, J. T. Lill, and J. Le Corff. 2002. Impact of timber harvest on species accumulation curves for oak herbivore communities in the Missouri Ozarks. Pp. 184-196 in: Proceedings of the Second Missouri Ozark Forest Ecosystem Project Symposium: Post-treatment Results of the Landscape Experiment (S. R. Shifley and J. M. Kabrick, Eds.). USDA Forest Service, North Central Research Station, Gen. Tech. Rep. NC-227, St. Paul, Minnesota.

Lill, J. T. 2001. Selection on herbivore life history traits by the first and third trophic levels: the devil and the deep blue sea revisitedEvolution 55: 2236-2247.

Lill, J. T., and R. J. Marquis. 2001. The effects of leaf quality on herbivore performance and attack from natural enemiesOecologia 126: 418-428.

Graham, W. K., V. L. Sork, R. Marquis, R. Renken, R. Clawson, J. Faaborg, D. Fantz, J. Le Corff, and J. Lill, and P. Poreneluzi. 2001. Evaluating the effects of ecosystem management: a case study in a Missouri Ozark forestEcological Applications 11: 1667-1679.

Lill, J. T. 1999. Structure and dynamics of a parasitoid community attacking larvae of Psilocorsis quercicella (Lepidoptera: Oecophoridae). Environmental Entomology 28: 1114-1123.

Gagné, R. J., and J. T. Lill. 1999. A new nearctic species of Lestodiplosis (Diptera: Cecidomyiidae) preying on an oak leaf tier, Psilocorsis quercicella (Lepidoptera: Oecophoridae). Proceedings of the Entomological Society of Washington 101: 332-336.

Lill, J. T. 1998. Density-dependent parasitism of the hackberry nipplegall maker (Homoptera: Psyllidae): a multi-scale analysis. Environmental Entomology 27: 657-661.

Auclair, A. N. D., J. T. Lill, and C. Revenga. 1996. The role of climate variability and global warming in the dieback of northern hardwoods. Water, Air, & Soil Pollution 91: 163-186.

Classes Taught

BISC 3461 - Plant-Animal Interactions
BISC 3460 - Conservation Biology
BISC 3462 - Plant-Animal Interactions Laboratory
BISC 243 - Graduate Seminar in Ecology