Kelly S. Johnson
RESEARCH INTERESTS: Insect physiological ecology, chemical ecology of insect-plant interactions, nutritional physiology, environmental toxicology and responses of aquatic macroinvertebrates to acid mine drainage
Evolution of feeding specialization and digestive strategies: Insects that feed on plants must overcome an array of chemical defenses that plants use to protect their tissues from herbivory, pathogens, and other environmental stressors. My research focuses on the toxicological mode of action of plant defensive compounds, especially phenolics, and the physiological/biochemical mechanisms that herbivorous insects use to overcome these defenses, both in an ecological and evolutionary sense. Past projects have addressed metabolic costs of hostplant specialization in Saturniid silkmoths, the evolution of digestive strategies in beetles, and the sequestration of potentially toxic pyrrolizidine alkaloids for chemical defense in Arctiid moths.
Oxidative stress in plant-feeding insects: A current interest is how dietary antioxidants (phenolics, ascorbate, glutathione, tocopherol and carotenoids) offset oxidative stress in rapidly growing insects feeding on plant foliage laden with pro-oxidants (phenolics, phenolases, peroxidases). My model system consists of Manduca sexta, the tomato hornworm caterpillar, and tomato, a popular plant model for the study of plant chemical defenses. Leaf phytochemistry can be manipulated via pharmacological agents, environmental stress or genetic modification.
Effect of environmental pollutants on diversity and
function of stream macroinvertebrates Many
streams in southeastern
Johnson, K. S. Antioxidant properties of plant phenolics in Manduca sexta hemolymph and midgut fluid. (in revision for J. Agric. Food Chem.).
Dsa, J. V., Johnson, K.S., Lopez, D., Kanuckel, C. and Tumlinson J. Residual toxicity of acid mine drainage-contaminated sediment after transplantation to a clean stream: contribution of acidity versus metals (submitted to Environmental Pollution).
Oppert, B. and Johnson, K. S., co-editors. 2004. Preface, Special Issue on Nutritional Physiology of Herbivorous Insects, Archives of Insect Biochemistry and Physiology 55.
Johnson, K. S., J. Last and G. Herrick. 2002. High tolerance of alderfly larvae (Sialis spp: Megaloptera) to metals is not affected by water pH. Bull. of Environmental Contam. and Toxicol. 69:370-377.
K. S., M. Hill, J. Last and C. Kanuckel. 2002. Aquatic macroinvertebrate responses to acid
mine impact in southeastern
Kelley, K.C., K.S. Johnson and M. Murray. 2002. Temporal modulation of pyrrolizidine alkaloid intake and genetic variation in performance of Utetheisa ornatrix caterpillars. J. Chem. Ecol. 28:669-685.
Johnson, K. S. and G. W. Felton. 2001. Plant phenolics as dietary antioxidants for herbivorous insects: a test with genetically modified tobacco. J. Chem. Ecol. 27:2579-2597.
Johnson, K. S. and G. W. Felton. 2000. Digestive proteinase activity in corn earworm (Helicoverpa zea) after molting and in response to lowered redox potential. Arch. Insect Biochem and Physiol.44:151-161.
Johnson, K. S. and D. Rabosky. 2000. Phylogenetic distribution of cysteine proteinases in beetles: Evidence for an evolutionary shift to an alkaline digestive strategy in Cerambycidae. Comp. Biochem. and Physiol.B 126:609-619.
Johnson, K. S. and R. V. Barbehenn. 2000. Oxygen levels in the gut lumens of herbivorous insects. J. Insect Physiology 46:897-903
Johnson, K. S. and G. W. Felton. 1999. (guest editors) Nutritional Physiology of Herbivorous Insects: Special Issue. Arch. Insect Biochem and Physiol. 1-99.
Johnson, K. S. 1999. Comparative detoxification of plant (Magnolia virginiana: Magnoliaceae) allelochemicals by generalist and specialist Saturniid silkmoths. J. Chemical Ecology 25:253-269.
Johnson, K. S. and G. W. Felton. 1996. Physiological and dietary influences on midgut redox conditions in generalist lepidopteran caterpillars. J. Insect Physiology 42:191-198.
Johnson, K. S. and G. W. Felton. 1996. Potential influence of midgut pH and redox potential on protein utilization in insect herbivores. Archives of Insect Biochemistry and Physiology. 32:85-105.
Johnson, K. S., J. M. Scriber, and M. Nair. 1996. Phenylpropanoid phenolics as chemical determinants of host use in Saturniid silk moths (Callosamia spp.). J. Chemical Ecology 22(11):1965-1979.
Johnson, K. S., D. Snider and J. M. Scriber. 1996. Estimate of genetic differentiation among three species of Callosamia (Saturniidae) from allozyme electrophoresis. J. Lepidopterist's Society 50(3):217-225
Johnson, K. S., F. Eischen
Johnson, K. S., J.M. Scriber, J.K. Nitao, and D. Smitley. 1994. Toxicity and persistence of Bacillus thuringiensis Berliner var. kurstaki to three non-target Lepidoptera in field studies. Environ. Entomol. 24:288-297.
Johnson, K. S. and J. M. Scriber. 1994.
"Geographic variation in plant allelochemicals of significance to
herbivores" . Chapter for
Functional Dynamics of Insect-Plant Interactions, ed. T. N. Ananthakrishnan.
Oxford & IBH Publishing Co. Pvt. Ltd.,
Nitao, J. K., K. S. Johnson, J. M. Scriber and M. Nair. 1992. Magnolia virginiana neolignan compounds as chemical barriers to swallowtail butterfly host use. J. Chemical Ecology 18(9):1661-1671.
Scriber, J. M., J. Potter and K. S. Johnson. 1991. Lack of physiological improvement in performance of Callosamia promethea larvae on local host plant favorites. Oecologia 86:232-235.
Nitao, J. K., M. Nair, D. Thorogood, K. S. Johnson
and J. M. Scriber. 1991. Novel neolignans
from the leaves of Magnolia virginiana.