- Author: Kathy Keatley Garvey
Professor Scott, who now resides in Luck, Wis., is internationally known for his work on the ecology and epidemiology of dengue, a mosquito-borne viral infection transmitted mainly by Aedes aegypti.
Only 1 percent of researchers make the global list of Highly Recited Researchers, as announced by Clarivate. The Web of Science Group, the information and technology provider for the global scientific research community, annually honors the 1 percent of scientists whose publications are the most cited in scientific papers.
One in 1000. "Of the world's scientists and social scientists, Highly Cited Researchers truly are one in 1,000," according to the Web of Science website.
Scott is one of 14 researchers from UC Davis--and one of some 6660 worldwide--to achieve the 2021 honor.
Scott's 19 publications listed in the report have been cited a total of 402 times. His most cited publication: “The Current and Future Global Distribution and Population at Risk of Dengue,” published in Nature Microbiology in 2019.
“Being a Highly Cited Researcher means a lot to me because it's an objective measure of the extent to which the scientific community finds helpful the work that my colleagues and I did,” said Scott, who joined the UC Davis Department of Entomology (now the Department of Entomology and Nematology) in 1996. “ I was privileged to work with exceptionally smart, hard-working, and insightful people. We had a lot of fun, but we also took our science seriously. We challenged each other in constructive and collegial ways. We are proud of the results of our efforts.”
“Because I enjoy it, I am continuing to explore science and public health,” Scott said. “Presently, I am involved in a variety of activities that range from writing manuscripts to kicking off new studies to serving on scientific and public health policy projects and committees. “
Healthy Cites, Healthy People. Scott co-chairs a Lancet Commission that focuses on how prevention of viruses transmitted by Aedes mosquitoes fits into the growing Healthy Cities, Healthy People movement. Lancet Commissions are tasked with identifying the most pressing issues in science, medicine, and global health, with the aim of providing recommendations that change health policy or improve practice. “In this case, we are making the case for Cities without Aedes,” Scott said. "We aim to reduce the burden and threat from Aedes transmitted viruses through improved construction and management of modern urban environments that build Aedes mosquitoes out of cities and towns.”
Scott is a collaborator in a clinical trial designed to demonstrate and quantify the protective efficacy of a spatial repellent to reduce human mosquito transmitted virus infection in Sri Lanka. “This new project,” he said, “builds on a randomized controlled clinical trial that my colleagues I recently completed in Iquitos, Peru, which revealed a significant protective efficacy of a spatial repellent against human infection. Publication of those results a currently under review.”
Scott's other activities include being a scientific advisor for a clinical trial in Brazil that is testing the public health benefit of Wolbachia for prevention of viruses transmitted by Aedes mosquitoes. “The study will assess the efficacy of releasing Wolbachia-infected Aedes aegypti into the environment in reducing human virus infection compared to standard vector control measures alone,” he said.
Scott serves on three World Health Organization committees, “which I find particularly rewarding because of their potential to improve public health policy and thus global health.”
Among his other activities:
- Chair of a group that is writing a chapter on Dengue Vector Control Guidelines that will be included in the updated version of WHO guidelines for dengue diagnosis, treatment, prevention, and control.
- Co-chair of the Wolbachia Evidence Review Group. “Mosquitoes infected with the endosymbionic bacteria Wolbachia are designed to have reduced capacity to become infected with and transmit a variety of viruses, which is expected to reduce human disease,” Scott explains. “Results from our deliberations will help the World Health Organization to develop guidelines for member States on the application of this exciting new intervention strategy.”
- Member of the World Health Organization Technical Advisory Group on the Global Integrated Arboviruses Initiative. The Arbovirus Initiative focuses on strengthening the coordination, communication, capacity building,research, preparedness, and response needed to mitigate the growing risk of epidemics due to arthropod transmitted viral diseases. Scott describes it as “a collaborative effort between the World Health Emergency Program, the Department of Control of Neglected Tropical Diseases, and the Immunization, Vaccines, and Biological Department at WHO. Members of the Technical Advisory Group have a broad range of expertise (clinical management, diagnostics, epidemiology, vector control, virology, vaccines, and travel medicine) and serve in an advisory capacity to WHO with a focus on essential and strategic guidance on management of disease. Our current focus is finalizing the Global Integrated Arboviruses Initiative, which will be presented to the World Health Assembly for review and approval.”
Scott, who holds bachelor and master's degrees from Bowling Green (Ohio) State University, received his doctorate in ecology in 1981 from Pennsylvania State University and did postdoctoral research in epidemiology at Yale University School of Medicine's Arbovirus Research Unit, part of the Department of Epidemiology and Public Health. He served on the faculty of the Department of Entomology, University of Maryland, from 1983 to 1996 before joining the UC Davis entomology faculty as a professor of entomology and director of the Vector-Borne Disease Laboratory. He was acting director of the UC Davis Center for Vector-Borne Research from 1996 to 1999, and director of the UC Davis Arbovirus Research Unit (2001-2003). He was selected vice chair of the Department of Entomology in 2006, serving until 2008.
Highly honored by his peers, Scott won the coveted Harry Hoogstraal Medal from the American Society of Tropical Medicine and Hygiene in 2018. His other honors include fellow of three organizations: American Society of Tropical Medicine and Hygiene (2014), Entomological Society of America (2010), and the American Association for the Advancement of Science (2008). He was named a UC Davis distinguished professor in 2014. In 2015, he won the Charles W. Woodworth Award, the highest honor awarded by the Pacific Branch of the Entomological Society of America.
Who's Who. The methodology that determines the “who's who” of influential researchers draws on the data and analysis performed by bibliometric experts and data scientists at the Institute for Scientific Information at Clarivate. It also uses the tallies to identify the countries and research institutions where these citation elite are based.
The complete list of UC Davis-affiliated scientists listed in the 2021 Highly Cited Researchers
- Andreas Bäumler, Medical Microbiology and Immunology, School of Medicine
- Eduardo Blumwald, Plant Sciences, College of Agricultural and Environmental Sciences
- Siobhan Brady, Plant and Animal Science, College of Agricultural and Environmental Sciences
- Mariana Byndloss, formerly with Medical Microbiology and Immunology, School of Medicine
- Magdalene Cerda, formerly with Emergency Medicine, UC Davis Health System
- Alan Crozier, Nutrition, College of Agricultural and Environmental Sciences
- Kathryn Dewey Nutrition, College of Agricultural and Environmental Sciences
- Jonathan Eisen, Evolution and Ecology, Medical Microbiology and Immunology, Genome Center, Center for Population Biology
- Oliver Fiehn, Genome Center
- Carlito Lebrilla, Chemistry, College of Letters and Science
- David A. Mills, Food Science and Technology, College of Agricultural and Environmental Sciences
- Sally Rogers, Psychiatry and Psychology, UC Davis Health System
- Thomas W. Scott,Entomology and Nematology, College of Agricultural and Environmental Sciences
- Andrew Sih, Environmental Science and Policy, College of Agricultural and Environmental Sciences
- Author: Kathy Keatley Garvey
Fischer, a member of the Mosquito Research Group, Department of Ecology, Genetics and Evolution, will speak on "The Recent Expansion of Aedes aegypti Distribution: Are the Populations Adapting to Colder Climate Regions?" at 4:10 p.m., Pacific Time. The Zoom link is https://ucdavis.zoom.us/j/99515291076.
She will be introduced by UC Davis doctoral student Erin Taylor Kelly of the laboratory of medical entomologist-geneticist Geoffrey Attardo.
"The mosquito Aedes aegypti, vector of dengue and other arboviruses, has recently expanded its distribution towards colder climate regions," Fischer says in her abstract. "This might be favored by an adaptation of the populations to local conditions. We explore the larval tolerance to low temperatures and the photo period-induced embryonic diapause as possible mechanisms occurring in temperate Argentina."
"My main research interest is on mosquito ecology, and my current project aims to analyze the effects of environmental conditions (photo period, temperature, humidity) and resources (larval food) on the fitness of Aedes aegypti," she writes on ResearchGate. "I am also interested in human caused environmental change and its consequences on vector borne diseases."
Fischer recently co-authored a research paper on Behavior of Aedes albifasciatus (Diptera: Culicidae) larvae from eggs with different dormancy times and its relationship with parasitism by Strelkovimermis spiculatus (Nematoda: Mermithidae).
Kelly, seminar host, researches the A. aegypti in the Attardo lab. She won a first-place award at the Entomological Society of America meeting last November with her poster, “Metabolic Snapshot: Using Metabolomics to Compare Near-Wild and Colonized Aedes aegypti.” She competed in the Physiology, Biochemistry and Ecology Section. (See https://bit.ly/3HJR0IF).
Fischer's talk meshes with the work of the Geoffrey Attardo laboratory. In one of his research projects, Attardo investigates the threat of these invasive mosquitoes, which have gained a foothold and spread throughout the state, putting California at risk for Aedes-vectored diseases such as dengue, chikungunya, Zika and yellow fever. Attardo studies the prevalence and physiology of insecticide resistance in Californian populations and evaluates the use of genetic markers to predict insecticide resistance and to track movement of genetically independent populations of aegypti throughout the state. Attardo and his lab are also currently developing novel biochemically oriented methods of insecticide resistance quantification to identify compounds that mosquito abatement districts can use for monitoring, and to define the biochemical pathways required to maintain this problematic adaptation.
The department's weekly seminars, held at 4:10 p.m. on Wednesdays, are coordinated by nematologist Shahid Siddique, who may be emailed at ssiddique@ucdavis.edu with any technical questions.
- Author: Kathy Keatley Garvey
Both in-person and virtual seminars will be broadcast via Zoom at https://ucdavis.zoom.us/j/
The schedule:
Jan. 5, 2022
Randa Jabbour, associate professor, agroecology, University of Wyoming
Virtual seminar
Title: "Interdisciplinary Collaborations in Pest Management Research--My Alfalfa Weevil Stories"
Host: Ian Grettenberger, assistant professor, UC Davis Department of Entomology and Nematology
Jan. 12, 2022
Sylvia Fischer, Mosquito Study Group, Department of Ecology, Genetics and Evolution, Universidad de Buenos Aires
Virtual seminar
Title: "Recent Expansion of Aedes aegypti Distribution: Are the Populations Adapting to Colder Climate Regions?"
Host: Erin "Taylor Kelly, doctoral student in the Geoffrey Attardo lab, UC Davis Department of Entomology and Nematology
Jan. 19, 2022
Megan Meuti, assistant professor, Department of Entomology, The Ohio State University
Virtual seminar
Title: "How Do Mosquitoes Correctly Interpret Environmental Signals into Complex Seasonal Responses?"
Host: Geoffrey Attardo, assistant professor, UC Davis Department of Entomology and Nematology
Tobin Hammer, postdoctoral researcher, University of Texas, Austin (he will start as an assistant professor in UC Irvine's Ecology and Evolutionary Biology Department in January 2022)
In-person seminar
Title: "Diversity and Dynamism in Social Bee Microbiomes"
Host: Rachel Vannette, associate professor, UC Davis Department of Entomology and Nematology
Feb. 2, 2022
Simon Niels Groen, assistant professor, Department of Nematology, UC Riverside
In-person seminar
Title: "Plant Toxins and the Evolution of Host-Parasite Interactions"
Host: Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology
Feb. 9, 2022
Vince D'Amico, research entomologist, Communities and Landscapes of the Urban Northwest, U.S. Department of Agriculture
In-person seminar
Title: "Monitoring and Ecological Research in the Forests of the BosWash Megalopolis"
Host: Geoffrey Attardo, assistant professor, UC Davis Department of Entomology and Nematology
Feb. 16, 2022
Michelle Heck, adjunct associate professor and research molecular biologist, Boyce Thompson Institute, Ithaca, N.Y.
Virtual seminar
Title: Topic to be announced (Her program uses a combination of molecular, genetic, and proteomics approaches to understand how insects transmit plant pathogens and how pathogens manipulate host plants to ensure replication and transmission. A second area of research is the development of new pest management tools to enhance cultural control and to provide new management strategies for insect vector-borne diseases in plants)
Host: Tiffany Lowe-Power, assistant professor, UC Davis Department of Plant Pathology
Feb. 23, 2022
Adam Steinbrenner, assistant professor, Department of Biology, University of Washington
In-person seminar
Title: "Plant Immune Recognition of Insect Herbivores"
Host: Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology
March 2, 2022
Erica Henry, postdoctoral scholar, conservation biology, North Carolina State University
In-person seminar
Title: "Insect Conservation in an Uncertain Future"
Host: Emily Meineke, assistant professor, UC Davis Department of Entomology and Nematology
March 9, 2022
Melissa Mitchum, professor, plant nematology, University of Georgia
Virtual seminar
Title: "The Tricks Phytonematodes Use to Modulate Plant Development"
Host: Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology
For any Zoom technical issues, Siddique may be reached at ssiddique@ucdavis.edu.
- Author: Kathy Keatley Garvey
The work, published in the current edition of Parasites & Vectors, a BioMed Central open-access medical journal, focuses on “determining how informative well-established genetic markers of resistance to pyrethroids are in predicting the resistance phenotype of individual mosquitoes of Aedes aegypti within a population,” said lead author Geoffrey Attardo, medical entomologist-geneticist in the UC Davis Department of Entomology and Nematology.
“Specifically, we generated mosquito colonies from invasive A. aegypti populations from four locations in the Central Valley (Dinuba, Clovis, Sanger and Kingsburg) and from collections in the Greater Los Angeles Area,” he said. “Mosquitoes from these populations have all demonstrated resistance to pyrethroid-type insecticides and we think this may be part of the reason why these mosquitoes have been so successful in spreading throughout California.”
A. aegypti transmits such viruses as dengue, Zika, chikungunya, and yellow fever. Despite California's aggressive surveillance and treatment efforts, this species presents a “significant challenge to local control agencies,” the nine-member team wrote in their research paper, “Frequency of Sodium Channel Genotypes and Association with Pyrethrum Knockdown Time in Populations of Californian Aedes aegypti.“
The paper is online and publicly accessible at https://bit.ly/3vmUxXR.
“What was interesting was that while all the mosquitoes from California show resistance to pyrethroids, there is a lot of variability from one individual to the next in terms of the level of resistance, even when they are carrying genetically identical resistance mutations,” Attardo said. “In particular, there seem to be two levels of resistance in these populations. The two levels seem to represent a resistant group and a super resistant group. However, the proportions of resistant/super-resistant differ in the sampled mosquitoes from population to population.”
Of particular interest was that mosquitoes carrying the resistance mutations at all five genetic locations were very resistant, he said. “However, there was also a large amount of unexplained variability in terms of the knockdown phenotypes demonstrated by mosquitoes of the same age and rearing conditions. We compared the knockdown times of mosquitoes positive for all five resistance mutations from different populations and found that these mutations account for only a proportion of the observed level of resistance. We believe that the unexplained variability is likely being mediated by the presence or absence of an undefined resistance mechanism.”
In launching the project, the researchers designed an assay “to test for the presence of mutations in the gene coding for the pyrethroid target protein, the voltage gated sodium channel (the para gene),” Attardo explained. “Detection of these mutations is used to monitor the level or resistance in populations. However, the actual link between the effect the genotype has on the phenotype of individual mosquitoes has not been looked at in detail. “
The scientists identified mutations from genetic sequences of Californian mosquitoes provided by co-author Yoosook Lee, a former UC Davis mosquito researcher now at the University of Florida-Florida Medical Entomology Laboratory, Vero Beach.
The authors also include research entomologist Anthony Cornel and staff research associate Katherine Brisco of the Mosquito Control Research Laboratory, Kearney Agriculture and Extension Center and UC Davis Department of Entomology and Nematology; and Lindsey Mack, Erin Taylor Kelly, Katherine Brisco, Kaiyuan Victoria Shen, Aamina Zahid, and Tess van Schoor, all with the UC Davis Department of Entomology and Nematology.
First, they tested the individual resistance phenotype of mosquitoes by placing them into bottles coated with the pyrethroid insecticide permethrin, and observed them to determine how long it takes for them to respond to the insecticide. Said Attardo: “This is a modified version of the assay used by the Center for Disease Control and Prevention to evaluate phenotypic resistance in groups of mosquitoes.”
Then they isolated the DNA from and performed a high-throughput genetic analysis on each individual to determine the composition of the five mutations in each individual. Next they looked at the resulting data to see how well knockdown time correlates with individual genotypes of mosquitoes.
Although A. aegypti was first detected in California in 2013, researchers believe that its arrival involved multiple introductions. Populations in Southern California are thought to have crossed the border from Mexico, while Central Valley populations may have been introduced, in part, from the southeastern United States.
“Upon detection in 2013, the Consolidated Mosquito Abatement District implemented an integrated vector control management strategy which involved extensive public education, thorough property inspections, sanitation, insecticide treatment at larval sources and residual barrier spraying with pyrethroids,” the authors wrote. Despite their efforts, the species successfully overwintered and continued to spread, implicating that it arrived in California with genetic mutations “conferring resistance to the type I pyrethroid insecticides applied for vector control in California.”
The project drew financial support from the Pacific Southwest Regional Center of Excellence for Vector-Borne Diseases, funded by the U.S. Centers for Disease Control and Prevention.
- Author: Kathy Keatley Garvey
The 11 scientists rank in the top 1 percent by citations, which represent how often their papers have been cited in other scientific papers.
Scott, who joined the UC Davis faculty in 1996, has published 288 papers to date. His total number of citations: more than 33,500. He is internationally known for his work on the ecology and epidemiology of dengue, a mosquito-borne viral infection transmitted mainly by Aedes aegypti.
“Although I retired from UC Davis in 2015, I have continued to carry out research just as I had previously,” Scott said. “In reality, I retired from UC Davis, but I did not retire from science.”
Scott focuses his research on epidemiology of mosquito-borne diseases, mosquito ecology, evolution of mosquito-pathogen interactions, and evaluation of novel products and strategies for disease control.
“I aim to generate the detailed, difficult to obtain data that are necessary for assessing current recommendations for disease prevention, rigorously testing fundamental assumptions in public health policy, and developing innovative, cost, and operationally effective strategic concepts for prevention of mosquito-borne disease.”
Scott has remained active on a variety of fronts. In 2015, he was in the early stages of two large grants (National Institutes of Health Program Project grant “Quantifying Heterogeneities in Dengue Virus Transmission Dynamics” and a sub-award from a Bill and Melinda Gates grant, “Spatial Repellent Products for Control of Vector-Borne Diseases”), which he continued to run and manage through the Department of Entomology and Nematology.
“So, I had plenty of support (more than $10 million) to continue my work,” he said. Both projects took place in Iquitos, Peru, and were jointly led with his long-term UC Davis collaborator, Amy C. Morrison, who is in the Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine.
The Gates grant was a clinical trial to determine whether and to what extent a chemical that repelled mosquitoes would reduce a person's risk of dengue or Zika virus infection. Scott served as the project leader for the Iquitos trial. “Earlier this year we determined that it had a big protective effect,” he related. “We are currently writing that manuscript.”
“Both of those grants ended earlier this year, but we still have a lot of work to do and will be busy for the next couple of years writing papers about those projects,” Scott said. He is currently working as a consultant in a follow-up study on spatial repellents for dengue prevention that will begin in Sri Lanka during 2021.
“Prior to and after retirement, I worked closely with the World Health Organization (WHO), where I served on numerous committees,” Scott related. He chaired the Vector Control Advisory Group, co-chaired the Global Vector Control Response, chaired the Emergency Response Consultation for Zika Virus, chaired the Technical Working Group for Dengue, served on the International Health Regulators Roster of Experts, and co-authored the updated version of WHO's dengue management and control guidelines. He recently applied for membership on the WHO Expert Advisory Group on Arboviruses.
“Working with WHO is important to me because at this stage of my career, being able to translate my science experience into improved quality of life, that is, improved public health policy, for other people, many of whom live in poverty, is the most meaningful thing I can do.”
Scott, who holds bachelor and master's degrees from Bowling Green (Ohio) State University, received his doctorate in ecology in 1981 from Pennsylvania State University and did postdoctoral research in epidemiology at Yale University School of Medicine's Arbovirus Research Unit, part of the Department of Epidemiology and Public Health. He served on the faculty of the Department of Entomology, University of Maryland, from 1983 to 1996 before joining the UC Davis entomology faculty as a professor of entomology and director of the Vector-Borne Disease Laboratory. He was acting director of the UC Davis Center for Vector-Borne Research from 1996 to 1999, and director of the UC Davis Arbovirus Research Unit (2001-2003). He was selected vice chair of the Department of Entomology in 2006, serving until 2008.
Highly honored by his peers, Scott won the coveted Harry Hoogstraal Medal from the American Society of Tropical Medicine and Hygiene in 2018. His other honors include fellow of three organizations: American Society of Tropical Medicine and Hygiene (2014), Entomological Society of America (2010), and the American Association for the Advancement of Science (2008). He was named a UC Davis distinguished professor in 2014. In 2015, he won the Charles W. Woodworth Award, the highest honor awarded by the Pacific Branch of the Entomological Society of America.
Other UC Davis scientists listed as Highly Cited Researchers include five others from the College of Agricultural and Environmental Sciences: Eduardo Blumwald and Jorge Dubcovsky, both from Plant Sciences; Alan Crozier, Nutrition; David A. Mills, Food Science and Technology; and Andrew Sih, Environmental Science and Policy.