Department of Entomology
In recent years hemlock forests in Kentucky and throughout eastern North America have been threatened by a highly invasive forest insect, the hemlock woolly adelgid, Adelges tsugae (HWA). HWA was first documented in the eastern USA in 1951, and in the mid-1980s, perhaps due to climatic factors, there was a very rapid and aggressive expansion of its geographic range. Since that time HWA has substantially expanded its distribution, interacting with biotic and abiotic stressors and causing extensive mortality of eastern hemlock. Initial reports of HWA in Kentucky occurred in 2006.
Extensive adelgid-induced hemlock mortality is imminent as HWA expands its range, and will have far-reaching consequences. We are evaluating changes in composition and structure of hemlock-dominated forests as HWA-induced mortality occurs. Projections predict a 98% decline in hemlock resources within 10 yr of infestation. Repercussions for riparian vegetation, stream characteristics, and associated biota are being evaluated. We are documenting differences between hemlock and non-hemlock streams with respect to stream chemistry and benthic macroinvertebrate communities. Because the adelgid is a relatively new arrival in the central/southern Appalachians and extensive hemlock mortality has not yet occurred, the full consequences of adelgid-affected forests in the region remains uncertain. Read more about this topic in the Summer 2007 U.K. Ag Magazine article, "They Don't Belong Here", and the Spring 2010 U.K. Odyssey magazine article, "Little Hemlock Horror."
Hemlock - adelgid interactions are under intense study in North America and several mechanisms underlying hemlock susceptibility are being investigated. Both eastern hemlock and Carolina hemlock are extremely susceptible to adelgid feeding; several mechanisms have been suggested as factors affecting this susceptibility. Though the feeding site and nutritional substrate of the hemlock woolly adelgid has been identified, little is known about species-specific or temporal differences in micromechanical properties of the stylet insertion point or in starch availability for feeding adelgids.
We’re investigating potential inter-specific variability in hemlock leaf cushion micromechanical properties and nutrient availability to feeding adelgids among hemlocks growing in a common garden. Because adult HWA are sessile, the ability of the crawlers to locate suitable host material is critical to colonization success. Differences in stylet penetration and nutrient availability during periods of crawler activity may provide a basis for HWA resistance among hemlocks. We’re using microindentation to evaluate hemlock leaf cushion micromechanical properties, and a histochemical approach to evaluate species-specific and temporal differences in starch reserves in the xylem ray parenchyma cells, the feeding substrate of the hemlock woolly adelgid, along a gradient from adelgid-resistant to adelgid-susceptible hemlocks.
I am always interested in motivated and qualified individuals for graduate research projects. If you are interested in pursuing a graduate degree in my areas of interest, please contact me at firstname.lastname@example.org.
• Post-doctoral Scholar
Abe Levin-Nielsen. Lab and Field manager
• Undergraduate student research projects
Jon Johnson, Fall 2012
Dodd, L.E., M.J. Lacki, E.R. Britzke, D.A. Buehler, P.D. Keyser, J.L. Larkin, A.D. Rodewald, T.B. Wigley, P.B. Wood, and L.K. Rieske. 2012. Forest structure affects trophic linkages: how silvicultural disturbance impacts bats and their insect prey. Forest Ecology and Management 267: 262-270.
Mallis, R.E. and L.K. Rieske. 2011. Arboreal spiders of eastern hemlock. Environmental Entomology 40: 1378-1387.
Cooper, W.R. and L.K. Rieske. 2010. Gall Structure Affects Ecological Associations of Dryocosmus kuriphilus (Hymenoptera: Cynipidae). Environmental Entomology 39, 787-797.
Spaulding, H.L. and L.K. Rieske. 2010. The aftermath of an invasion: Structure and composition of Central Appalachian hemlock forests following establishment of the hemlock woolly adelgid, Adelges tsugae. Biological Invasions. DOI: 10.1007/s10530-010-9704-0.
Cooper, W.R. and L.K. Rieske. 2009. Woody stem galls interact with foliage to affect community associations. Environmental Entomology 38, 417-424.
Lensing, J.R., L.K. Rieske, C.W. Harper, J.T. Collins, and J.J. Obrycki. 2008. A tale of success: Preventing establishment of the gypsy moth in Kentucky. American Entomologist 54, 138-143.
Rieske, L.K. and D.N. Dillaway. 2008. Response of two oak species to extensive defoliation: Tree growth and vigor, phytochemistry, and herbivore suitability. Forest Ecology and Management 256, 121-128.
Joshua Clark, M.S., May 2010. Using remotely sensed data to map an exotic invader: the hemlock woolly adelgid and eastern hemlock in Kentucky. Co-directed with J. Obrycki and S. Fei (Dept. Forestry).
Heather Spaulding, M.S., December 2009. Modeling future forests in the wake of invasive species establishment.
Paul Ayayee, M.S., May 2009. Hemlock characteristics influence susceptibility to the invasive hemlock woolly adelgid. [Currently a PhD student in the Department of Entomology at Penn State]
W. Rodney Cooper, Ph.D., December 2007. “Chestnut defenses affect generalist and specialist herbivore responses and influence community dynamics.” [Currently a Research Scientist for USDA ARS Laboratory, Shaftner, CA]
Ryan McEwan, Post-doctoral Scholar 2006, PhD Ohio University (2006), worked a collaborative project between L. Rieske-Kinney and M. Arthur (Forestry) on the effects of Lonicera maackii invasion on ecosystem function. [Currently an Assistant Professor at the University of Dayton]
Tom W. Coleman, Ph.D., December 2006. “Natural and anthropogenic forest disturbances alter forest composition, structure, and succession, and influence arthropod communities.” [Currently a Scientist for the US Forest Service Forest Health Protection Unit, San Bernardino, CA]
Aerin Land, M.S., May 2006. “Prescribed fire influences shortleaf pine regeneration and herbivore pressure following southern pine beetle mortality.” [Employed with the US Department of Interior, Everglades National Park, Homestead, FL]
Beth Choate, M.S., May 2005. “Life history and dispersal patterns of Malacasoma americanum, the insect associated with mare reproductive loss syndrome.” [Currently enrolled in a PhD program in the Department of Entomology, University of Maine]
Shelly K. Kellogg, M.S., December 2004. “Blight resistance and gall wasp attack influence foliar properties and herbivore susceptibility in chestnut.” [Employed as Agricultural Inspector, US Department of Homeland Security, Charlotte, NC]
Leslie Foss, M.S., October 2002. “Response of the gypsy moth to species-specific and gall-induced differences in oaks.” [Currently employed with USDA APHIS]
Heather Housman, M.S., December 2001. Department of Forestry co-advisee. [Currently employed by the Kentucky State Nature Preserves Commission]
Aaron S. Adams, M.S., February 2000. “Interactions between prescribed fire and herbivory: Effects on oak regeneration.” [Currently a Research Scientist in the Department of Entomology, University of Wisconsin]
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