Postdoctorals
Education
Ph.D. 2007 University of California, Riverside. Entomology. Advisor: Dr. John Trumble. Title: Assessing impacts of anthropogenic pollutants on selected aquatic and terrestrial insects.
B.S. 2003. University of California, Berkeley.Molecular Environmental Biology, emphasis in Insect Biology
Research Focus
Applied insect ecology, insect-plant interactions, impacts of anthropogenic disturbance.
My current project focuses on the nutritional ecology and foraging behavior of the caterpillar Manduca sexta. In the laboratory, it has been shown that M. sexta (Lepidoptera: Sphingidae), when offered a choice of two artificial diets, will eat selectively from each of the two diets to reach a nutrient target, a particular ratio of protein and carbohydrate. I am investigating M. sexta foraging behavior to determine if, when foraging in a more natural setting, these insects selectively seek out and consume different plant parts to regulate protein and carbohydrate intake. Theoretically, such behavior would increase fitness by allowing the insect to reach an optimum nutrient target by eating young, protein-rich leaves as well as with older, carbohydrate-biased foliage.
Past projects have examined the effects of anthropogenic pollutants on insect ecosystems, using model organisms from aquatic and terrestrial food webs. My research went beyond mortality to look at less-understood effects of pollution, including sub-lethal effects like slowed development, changes in behavior, altered sex ratios, and decreased fertility or fecundity; as well as effects on interspecific interactions, including predation, parasitism, and competition. My findings underscore the very important point that not all taxa in a system will be equally affected by contamination: toxicity is dependent on the particular species and contaminant involved, as well as a combination of environmental factors.
Selected Publications
Sorensen, M.A., J.A. Bethke, and R.A. Redak. Potential Trirhabda geminata Horn (Coleoptera: Chrysomelidae) host plants: impacts on survival, development and feeding. Submitted to Environmental Entomology.Sorensen, M.A., D.R. Parker, and J.T. Trumble. 2009. Pollutant acquisition by the invasive weed saltcedar (Tamarix ramosissima) and transfer to the biological control agent Diorhabda elongata (Coleoptera: Chrysomelidae). Environmental Pollution 157:384-391.
Sorensen, M.A., C.M. Chase-Dunn, and J.T. Trumble. 2009. Chronic exposure to elevated levels of manganese and nickel is tolerated by a cosmopolitan detritivore, Megaselia scalaris (Loew) (Diptera: Phoridae). Insect Science 16:73-79.
Trumble, J.T., and M.A. Sorensen. 2008. Selenium and the elemental defense hypothesis. New Phytologist 177:569-572.
Sorensen, M.A., W.E. Walton and J.T. Trumble. 2007. Impact of the inorganic pollutants perchlorate and hexavalent chromium on the efficacy of Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis against Culex quinquefasciatus (Diptera:Culicidae). Journal of Medical Entomology 44: 811-816.
Jensen, P.D., M.A. Sorensen, W.E. Walton and J.T. Trumble. 2007. Lethal and sublethal responses of an aquatic insect Culex quinquefasciatus (Diptera: Culicidae) challenged with individual and joint exposure to dissolved sodium selenate and methylmercury chloride. Environmental Toxicology 22: 287-294.
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(3): 759-764. Book Chapters
Sorensen, M.A. and J.T. Trumble. 2004. Bioavailability and bioremediation of perchlorate salts. Pp 349-363. In: Bodari, Editor, Recent Research Developments in Environmental Biology. Trivandrum, India.