Individual Listing

BOYDEN LAB
University of California
Riverside, CA 92521

Walker, Gregory

Professor of Entomology

College of Natural and Agricultural Sciences

Entomology


Biography

Research specialization - Current research in our lab is in the general area of insect-plant interactions with a focus on piercing-sucking insects such as whiteflies, aphids and leafhoppers. Because piercing-sucking insects can pick and choose which plant tissues and cells that they feed on, the physiological interactions between piercing-sucking insects and the plants that they feed on are much more intricate than they are for chewing insects, making this a particularly interesting area of study. The overall goal of our research is to identify and understand mechanisms by which plants can be resistant to these insects. Studies in our lab vary from the very applied level, identifying resistant plant genotypes, to the basic level, determining mechanisms of resistance. Our research encompasses field and greenhouse studies screening for resistance, and detailed laboratory studies on feeding behavior, the physiological response of the plants to insect feeding, and the response of the insects to plant defenses. In a newly funded project, we also will be examining the plant molecular response to feeding by piercing-sucking insects. We also are involved in three-trophic-level studies to determine mechanisms of plant virus transmission by piercing-sucking insects. Most of the agriculturally important plant viruses are transmitted by piercing-sucking insects so, like our plant resistance studies, our plant-virus-insect studies also have practical ramifications.

Degrees

BA Zoology 1975

Miami University, Oxford, OH

MS Entomology 1979

Ohio State University

PhD Entomology 1982

Ohio State University

Research Area

Insect-plant interactions with piercing-sucking insects including feeding behavior, host-plant selection and discrimination, mechanisms of host-plant resistance, and mechanisms of transmission of plant pathogens

Publications

Recent Publications

Stafford, C. A. & G. P. Walker. 2009. Characterization and correlation of DC electrical penetration graph waveforms with feeding behavior of beet leafhopper, Circulifer tenellus. Entomologia Experimentalis et Applicata 130:113-129.

Stafford, C. A. & G. P. Walker, R. Creamer. 2009. Stylet penetration behavior resulting in inoculation of Beet severe curly top virus by beet leafhopper, Circulifer tenellus. Entomologia Experimentalis et Applicata 130:130-137.

Symmes, E. J., G. P. Walker & T. M. Perring. 2008. Stylet penetration behaviors of Myzus persicae related to transmission of Zucchini yellow mosaic virus. Entomologia Experimentalis et Applicata 129:258-267.

Kasetty, S., C. Stafford, G. P. Walker, X. Wang, & E. Keogh. 2008. Time series classification and anomaly detection on resource aware sensors. 20th IEEE International Conference on Tools with Artificial Intelligence 149-156.

Walker, G. P., C. A. Stafford, E. J. Symmes & R. Goh. 2008. Phenology and descriptions of two sympatric native whiteflies (Hemiptera: Aleyrodidae) with a high degree of niche overlap. Pan Pacific Entomologist 84:37-51.

Bayoun, I. M., G. P. Walker & S. V. Triapitsyn. 2008. Parasitization of beet leafhopper eggs, Circulifer tenellus, in California. Journal of Applied Entomology 132: 412-424.

Jiang, Y. X. & G. P. Walker. 2007. Identification of phloem sieve elements as the site of resistance to silverleaf whitefly in resistant alfalfa genotypes. Entomologia Experimentalis et Applicata 125: 307-320.

Walker, G. P. & E. T. Natwick. 2006. Resistance to silverleaf whitefly, Bemisia argentifolii (Hem., Aleyrodidae), in Gossypium thurberi, a wild cotton species. Journal of Applied Entomology 130: 429-436.

Walker, G. P., I. M. Bayoun, S. V. Triapitsyn & J. Y. Honda. 2005. Taxonomy of Aphelinoidea (Hymenoptera: Trichogrammatidae) species attacking eggs of the beet leafhopper, Circulifer tenellus (Hemiptera: Cicadellidae), in California. Zootaxa 1068: 1-25.

Jiang. Y. X., G. P. Walker. 2003. Electrical penetration graphs of the nymphal stage of Bemisia argentifolii. Entomologia Experimentalis et Applicata 109: 101-111. 

Jiang, Y. X., N. Zareh, G. P. Walker, L. R. Teuber. 2003. Characterization of alfalfa germplasm expressing resistance to silverleaf whitefly, Bemisia argentifolii. Journal of Applied Entomology 127: 447-457. 

Johnson, D. D., G. P. Walker, R. Creamer. 2002. Stylet penetration resulting in inoculation of a semipersistently transmitted closterovirus by the whitefly Bemisia argentifolii. Entomologia Experimentalis et Applicata 102: 115-123. 

Natwick, E. T., G.P. Walker. 2002. Silverleaf whitefly resistance in the cotton relative, Gossypium thurberi. 2002. Proceedings of the Beltwide Cotton Conference.

Walker, G. P. 2002. Overview of whitefly feeding behavior: What we know and what we need to know. In: Silverleaf Whitefly: National Research, Action, and Technology Transfer Plan: Fourth Annual Review of the Second 5-Year Plan and Final Report for 1992-2002. USDA/ARS. (T. J. Henneberry, R. M. Faust, W. A. Jones, & T. M. Perring, eds.). pp. 49-53.

Luft, P. A., T. D. Paine & G. P. Walker. 2001. Interactions of Colonisation Density and Leaf Environments on Survival of Trioza eugeniae Nymphs. Ecological Entomology 26: 263-270.

Jiang, Y. X. and G. P. Walker. 2001. Pathway phase waveform characteristics correlated with length and rate of stylet advancement and partial stylet withdrawal in AC electrical penetration graphs of adult whiteflies. Entomologia Experimentalis et Applicata 101: 233-246. 

Chu, C. C., T. P. Freeman, J. S. Buckner, T. J. Henneberry, D. R. Nelson, G. P. Walker & E. T. Natwick. 2000. Bemisia argentifolii (Homoptera: Aleyrodidae) Colonization on Upland Cottons and Relationships to Leaf Morphology and Leaf Age. Annals of the Entomological Society of America 93: 912-919.

Walker, G. P. & E. A. Backus [eds.]. 2000. Principles and Applications of Electronic Monitoring and Other Techniques in the Study of Homopteran Feeding Behavior. Thomas Say Publications in Entomology, Entomological Society of America. 

Al-Wahaibi, A. K. and G. P. Walker. 2000. Oviposition Behavior of Anagrus nigriventris, An Egg Parasitoid of Beet Leafhopper, Circulifer tenellus. BioControl 45: 139-153

Al-Wahaibi, A and G. P. Walker. 2000. Searching and oviposition behavior of a mymarid egg parasitoid, Anagrus nigriventris, on five host plant species of its leafhopper host, Circulifer tenellus. Entomologia Experimentalis at Applicata 96: 9-25.

Johnson, D. D. & G. P. Walker. 1999. Intracellular punctures by the adult whitefly Bemisia argentifolli on DC and AC electronic feeding monitors. Entomologia Experimentalis et Applicata 92-257-270.