College of Natural & Agricultural Sciences


William Walton

William E. Walton

Professor of Entomology and Department Vice Chair

BS Zoology 1978

University of Rhode Island

MS Zoology/Aquatic Ecology 1982

University of Maryland

PhD Zoology/Aquatic Ecology 1986

University of Maryland

Research Areas

IPM of vector and pest arthropods particularly mosquitoes. Biogeography of freshwater flora and fauna. Trophic interactions of freshwater food webs.

Contact Information
Entomology Museum 206
(951) 827-3919

Research Specialization - A major emphasis of research in my laboratory is to integrate studies of mosquito biology and ecology with the design of control methodologies for pestiferous and pathogen-transmitting mosquitoes in wetlands. Natural and constructed wetlands can be important developmental sites of mosquitoes. Multipurpose wetlands are being constructed to recycle precious water resources in arid southern California, to create habitat for wildlife, and to provide recreational activities for the ever increasing human population in the region. As design, construction, and operational criteria for man-made wetlands are established and evaluated, the development of effective mosquito abatement programs that protect the encroaching human population from disease and from nuisance biting of mosquitoes is necessary. A major emphasis of work in my laboratory is the design and implementation of novel and practical management strategies for wetland mosquitoes. In addition to applied research on mosquito control, basic research on the population dynamics of larval mosquito populations, the interaction of mosquitoes with natural enemies, and the influence of vegetation on the temporal and spatial distribution of mosquito larvae in wetlands is ongoing. Much of our work focuses on the predominant vector of viruses causing human encephalitis and western equine encephalomyelitis in California, Culex tarsalis, and on the tule mosquito, Culex erythrothorax. Understanding the relative importance of factors regulating mosquito larval populations is critical for our continuing efforts to evaluate the effectiveness of large-scale mosquito abatement programs utilizing biological control agents, such as larvivorous fishes, and integrated control programs using bacterial larvicides and larvivorous taxa. Other ongoing studies in my laboratory include investigation of the behavior of larval and adult mosquitoes, the efficacy of larvivorous fishes against mosquitoes, the interactions among stream insects, the biogeography of freshwater flora and fauna and trophic interactions of freshwater food webs, and the evolution of resistance in mosquitoes to bacterial insecticides.

Awards Received

2012-13: National Academies Education Fellow in the Life Sciences, National Academy of Sciences

2012-13: President, Society for Vector Ecology

2010: EGSA Faculty Mentor Award

2010: Who's Who in Science and Engineering


Walton, W.E.  2012. Design and management of free water surface constructed wetlands to minimize mosquito production. Special Issue on “Wetlands and Human Health”. Wetlands Ecology and Management. 20(3):173-195..

Wirth, M. C., W. E. Walton, and B. A. Federici. 2012. Inheritance, stability, and dominance of Cry resistance in Culex quinquefasciatus (Diptera: Culicidae) selected with the three Cry toxins of Bacillus thuringiensis subsp. israelensis. Journal of Medical Entomology 49: 886-894.

Walton, W. E., D. A. Popko, A. R. Van Dam, A. Merrill, J. Lythgoe, and B. Hess. 2012. Width of planting beds for emergent vegetation influences mosquito production from a constructed wetland in California (USA). Ecological Engineering 42: 150-159.

Pachón, R.T., and W. E. Walton. 2011. Seasonal occurrence of black flies (Diptera: Simuliidae) in a desert stream receiving trout farm effluent. Journal of Vector Ecology 36:187-196.

Walton, W.E., J. A. Henke, and A. M. Why. 2011. Gambusia affinis (Baird and Girard) andGambusia holbrooki Girard (Mosquitofish). Chap. 22. Pp. 261-273. In: R. Francis (ed.), A Handbook of Global Freshwater Invasive Species. Earthscan. London, U.K.

Berg, J. A., M. G. Felton, J. L. Gecy, A. D. Laderman, C. R. Mayhew, J. L. Mengler, W. H. Meredith,  N. R. Read, J. R. Rey, C. Roberts, G. E. Sakolsky-Hoopes, W. E. Walton, R. J. Wolfe.  2010.  Mosquito Control and Wetlands. Wetland Science and Practice 27(2): 24-34.

 Wirth, M. C., W. E. Walton and B. A. Federici. 2010. Evolution of resistance to the Bacillus sphaericus Bin toxin is phenotypically masked by combination with the mosquitocidal proteins of Bacillus thuringiensis subspecies israelensis. Environmental Microbiology 12: 1154-1160.

 Walton, W. E., A. R. Van Dam and D. A. Popko. 2009. Ovipositional responses of two Culex (Diptera: Culicidae) species to larvivorous fish. Journal of Medical Entomology 48: 1338-1343.

Walton, W. E. 2009. Effectiveness of pyramidal emergence traps for estimating production of Culex mosquitoes (Diptera: Culicidae). Journal of the North American Benthological Society 28: 676-682.

Van Dam, A. R. and W. E. Walton. 2008. The effect of predatory-fish exudates on the ovipositional behaviour of three mosquito species: Culex quinquefasciatusAedes aegyptiand Culex tarsalis. Medical and Veterinary Entomology: 22:399-404. 

Peck, G. W. and W. E. Walton. 2008. Effect of mosquitofish (Gambusia affinis) and sestonic food abundance on the invertebrate community within a constructed treatment wetland. Freshwater Biology: 53: 2220-2233. 

Van Dam, A. R. and W. E. Walton. 2007. Comparison of mosquito control provided by the arroyo chub (Gila orcutti) and the mosquitofish (Gambusia affinis). Journal of the American Mosquito Control Association 23: 430-441. 

Wirth, M. C., Y. Yang, W. E. Walton, B. A. Federici, and C. Berry. 2007. Mtx toxins Synergize Bacillus sphaericus and Cry11Aa against susceptible and insecticide-resistant Culex quinquefasciatus. Applied and Environmental Microbiology: 73 (19): 6066-6071. 

Walton, W. E. 2007. Larvivorous fish including Gambusia. In: "Biorational Control of Mosquitoes." (T. Floore, ed.). American Mosquito Control Association, Mount Laurel, NJ. Journal of the American Mosquito Control Association 23(2) Suppl. 184-220. 

Walton, W. E., M. C. Wirth and P. W. Workman. 2007. Environmental factors influencing survival of threespine stickleback (Gasterosteus aculeatus) in a multipurpose constructed treatment wetland in southern California. Journal of Vector Ecology 32: 90-105. 

Popko, D. A., S.-K. Han, B. L. Lanoil, and W. E. Walton. 2006. A molecular ecological analysis of planktonic bacterial communities in constructed wetlands invaded by Culex(Diptera: Culicidae) mosquitoes. Journal of Medical Entomology 43: 1153-1163. 

Peck, G. W. and W. E. Walton. 2006. The effect of bacterial food quality and density on growth and whole body stoichiometry of Culex quinquefasciatus and Culex tarsalis(Diptera: Culicidae). Journal of Medical Entomology 43: 25-33. 

Sorensen, M. A., P. D. Jensen, W. E. Walton and J. T. Trumble. 2006. Acute and chronic activity of perchlorate and hexavalent chromium contamination on the survival and development of Culex quinquefasciatus Say (Diptera: Culicidae). Environmental Pollution 144: 759-764. 

Sanford, M.R., K. Chan and W.E. Walton. 2005. Effects of inorganic nitrogen enrichment on mosquitoes (Diptera: Culicidae) and the associated aquatic community in a constructed treatment wetland. Journal of Medical Entomology. 42: 766-776. 

Park, H.-W., D.K. Bideshi, M.C. Wirth, J.J. Johnson, W.E. Walton and B.A. Federici. 2005. Recombinant larvicidal bacteria with markedly improved efficacy against Culex vectors of West Nile virus. Amer. Journ. Trop. Med. and Hyg. 72: 732-738. 

Wirth, M.C., J.A. Jiannino, B.A. Federici and W.E. Walton. 2005. Evolution of resistance to Bacillus sphaericus or a mixture of B. sphaericus + Cyt1A from Bacillus thuringiensis in the mosquito Culex quinquefasciatus (Diptera: Culicidae). J. Invert. Path. 88: 154-162. 

Knight, R. L., W. E. Walton, G. F. O'Meara, W. K. Reisen, and R. Wass. 2003. Strategies for effective mosquito control in constructed treatment wetlands. Ecological Engineering 21: 211-232. 

Walton, W. E. 2003. Managing mosquitoes in surface-flow constructed treatment wetlands. University of California, Division of Agriculture and Natural Resources. Davis, CA. Publ. No. 8117. 11 pp.

Thullen, J. S., J. J. Sartoris and W. E. Walton. 2002. Effects of vegetation management in constructed wetland treatment cells on water quality and mosquito production. Ecological Engineering 18: 441-457. 

Walton, W. E. 2002. Multipurpose constructed treatment wetlands in the arid southwestern United States: Are the benefits worth the risks? pp. 115-123. In: J. Pries (ed.) Treatment Wetlands for Water Quality Improvement: Quebec 2000 Conference Proceedings. CH2M HILL Canada Limited, Pandora Press, Waterloo, ON. 

Keiper, J. B., W. E. Walton and B. A. Foote. 2002. Biology and ecology of higher Diptera from freshwater wetlands. Annual Review of Entomology. 47: 207-232.

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