My research interests focus 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, behavior, 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. Along with students, I am also investigating the effects of climate change on species interactions.
Evolutionary Ecology of Tritrophic Interactions
I investigate how seasonal changes in host plant quality and the risk of attack from natural enemies jointly shape the diet breadth, behavior, phenology, and life history traits of 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 morphology, behavior, and life history. Over the last decade, I have used three main systems, slug caterpillars (Limacodidae), fall webworms (Erebidae) and silver-spotted skippers (Hesperiidae), to experimentally investigate the ecological consequences of feeding on alternative host plants.
Arthropod Community Ecology
I have been involved in several projects that have a common goal: to understand the role that species 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. Recent work in my lab) focused on testing for priority effects on the community assembly process and examining competitive interactions among leaf-tying caterpillars within leaf ties. I am looking for students interested in ecosystem engineering and the arthropod community ecology who might be interested in further exploring this study system.
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.
Species Interaction Webs. Having spent the last two decades rearing large numbers of wild-collected herbivores from the field, I am excited to begin constructing and analyzing the structure of plant-herbivore-natural enemy interaction webs that include both parasitoids and arthropod predators.
Research into the effects of climate change on species distribution and range has moved beyond single-species studies to focus on species interactions. Recent research in my lab has focused on experimentally examining the effects of climate warming on the phenology of spring-feeding folivores (eastern tent caterpillars) and their egg parasitoids and the fitness consequences of asynchrony for both hosts and parasitoids. My current Ph.D. student, Ryan Spahn, is beginning investigations into the effects of experimental warming on host-parasitoid interactions. My current Ph.D. student, Ryan Spahn, is completing her dissertation which explores how experimental warming can alter plant-caterpillar-parasitoid interactions in Brassica agroecosystems.
Together with my long-term collaborator, Dr. Martha Weiss (Georgetown University), and my current postdoctoral associate, Dr. Zoe Getman-Pickering, we have been investigating the ecological impacts of the 2021 Brood X periodical cicada emergence on the trophic dynamics of a local forest food web. The goal of this research is to document the direct and indirect effects of a massive pulse of insect biomass on the trophic interactions and resulting population dynamics of insectivorous birds, caterpillars, parasitoids, and plants in a local oak forest.
Brackley, A., J. T. Lill, and M. R. Weiss. 2021. Adaptive ontogenetic shifts in larval responses to environmental cues. Entomologia Experimentalis et Applicata doi: 10.1111/eea.13114
Oppenheimer*, R. L., and J. T. Lill. 2021. A Plant-bee visitation network for Plummers Island, MD. Proceedings of the Washington Entomological Society 123: 365-381.
Lill, J. T., M. R. Weiss, C. Block, and R. R. Kula. 2020. Larval parasitism of the silver spotted skipper, Epargyerus clarus (Cramer) (Lepidoptera: Hesperiidae). Proceedings of the Washington Entomological Society (in press).
Vidal, M., J. T. Lill, R. J. Marquis, and S. M. Murphy. 2020. Geographic variation in performance of a widespread generalist insect herbivore. Ecological Entomology
Abarca, M., J. T. Lill, and M. R. Weiss. 2020. Host plant and thermal stress induce supernumerary instars in caterpillars . Environmental Entomology 49: 123-131.
Marquis, R. J., J. T. Lill, R. E. Forkner, J. Le Corff, J. M. Landosky, and J. B. Whitfield. 2019. Declines and resilience of communities of leaf chewing insects on Missouri oaks following spring frost and summer drought. Frontiers in Ecology and Evolution doi: 10.3389/fevo.2019.00396
Abarca, M. and J. T. Lill. 2019. Latitudinal variation in the phenological responses of eastern tent caterpillars and their egg parasitoids. Ecological Entomology 44: 50-61.
Abarca, M., E. A. Larsen, J. T. Lill, M. Weiss, E. Lind, and L. Ries. 2018. Inclusion of host quality data improves predictions of herbivore phenology. Entomologia Experimentalis et Applicata 166: 648-660.
Abarca, M. and J. T. Lill. Latitudinal variation in the phenological responses of eastern tent caterpillars and their egg parasitoids. Ecological Entomology 2018 (in press).
Forister, M. L., Novotny, V., Panorska, A. K., Baje, L., Basset, Y., Butterill, P. T., Cizek, L., Coley, P. D., Dem, F., Diniz, I. R., Drozd, P., Fox, M., Glassmire, A., Hazen, R., Hrcek, J., Jahner, J. P., Kama, O., Kozubowski, T. J., Kursar, T. A., Lewis, O. T., Lill, J., Marquis, R. J., Miller, S. E., Morais, H. C., Murakami, M., Nickel, H., Pardikes, N., Ricklefs, R. E., Singer, M. S., Smilanich, A. M., Stireman, J. O., Villamarín-Cortez, S., Vodka, S., Volf, M., Wagner, D. L., Walla, T., Weiblen, G. D., and L. A. Dyer. 2015. The global distribution of diet breadth in insect herbivores. Proceedings of the National Academy of Sciences 112: 442-447.
Stoepler, T. M., J. Castillo, J. T. Lill and I. Eleftherianos. 2013. Hemocyte density increases with developmental stage in an immune-challenged forest caterpillar. PloS One 8:
Stoepler, T. M. and J. T. Lill. 2013. Direct and indirect effects of light environment generate ecological trade-offs in herbivore performance and parasitism. Ecology 94: 2299-2310.
Sigmon, E., and J. T. Lill. 2013. Phenological variation in the composition of a temperate forest leaf tie community. Environmental Entomology 42: 29-47.
Gates, M. W., J. T. Lill, R. R. Kula, J. E. O’Hara, D. R. Smith, J. B. Whitfield, S. M. Murphy, T. M. Stoepler, and M. E. Epstein. 2012. Review of parasitoid wasps and flies (Hymenoptera, Diptera) associated with Limacodidae (Lepidoptera) in North America, with a key to genera. Proceedings of the Washington Entomological Society 114: 24-110.
Forister, M. L., L. A. Dyer, M. S. Singer, J. O. Stireman, and J. T. Lill. 2012. Progress and perspectives in the study of ecological specialization, with emphasis on insect-plant interactions. Ecology 93: 981-991.