- Author: Kathy Keatley Garvey
"The world's primary arboviral vector, Aedes aegypti, was reintroduced into California in 2013," Kelly says in her abstract. "Its re-establishment throughout the state appears to be due, in part, to the failure of pyrethroid insecticides applied for adult mosquito control. My dissertation work examines 1) population dynamics within the state 2) how mosquito metabolism is impacted by pyrethroid exposure and 3) how a pyrethroid susceptible reference strain of Aedes aegypti differs physiologically from a wild California Ae. aegypti population. This research describes a successful story of ˆexclusion and generated novel hypotheses about the physiological underpinnings of the fitness costs and tradeoffs observed in insects withthepyrethroid resistance phenotype. Additionally, I explore novel targets for insecticide synergism."
Kelly is president of the Entomology Graduate Student Association (EGSA), and served two terms as president of the UC Davis Equity in STEM and Entrepreneurship (ESTEME).
Active in the Entomological Society of America, Kelly was a member of the UC Davis team that won the national Entomology Games championship in 2022. The UC Davis team included three other doctoral candidates from the Department of Entomology and Nematology: Zachary Griebenow of the Phil Ward lab, captain; Jill Oberski of the Ward laboratory; and Madison “Madi” Hendrick of the Ian Grettenberger lab.The event is a lively question-and-answer, college bowl-style competition on entomological facts played between university-sponsored student teams. The question categories include biological control, behavior and ecology, economic and applied entomology, medical, urban and veterinary entomology, morphology and physiology, biochemistry and toxicology, systematics and evolution integrated pest management and insect/plant interactions.
Other academic highlights:
- Kelly was selected the recipient of the 2022 Student Leadership Award from the Pacific Branch of ESA, which encompasses 11 Western states, parts of Canada and Mexico and several U.S. territories. (See news story)
- She won a first-place award at the 2021 Entomological Society of America (ESA) meeting with her poster, “Metabolic Snapshot: Using Metabolomics to Compare Near-Wild and Colonized Aedes aegypti.”
Taylor, who joined the Attardo lab in 2018, holds a bachelor of science degree in biology, with a minor in chemistry, from Santa Clara University, where she served as president of the campuswide Biology Club and led STEM projects, encouraging and guiding underrepresented students to seek careers in science, technology, engineering and mathematics (STEM).
Her future plans? "I'm pursuing vector ecologist positions within California vector control programs!"
(Editor's Note: For the Zoom password, contact associate professor Geoffrey Attardo at gmattardo@ucdavis.edu or Taylor Kelly at etkelly@ucdavis.edu.)
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- Author: Kathy Keatley Garvey
Her seminar takes place at 3:30 in 366 Briggs Hall, and also will be on Zoom.
Mack studies Aedes aegypti with a focus on analysis of transcriptomic datasets and 3D imaging datasets. "Throughout my time in graduate school, my projects have considered pyrethroid resistance in Aedes aegypti ;examining the genetic response to this insecticide. As I finish up my dissertation, I hope to pursue a career in industry using the skills I've developed to continue to analyze large datasets!"
Insecticide resistance is a global issue, Mack says in her exit seminar abstract. Ae. aegypti, known as "the yellow fever mosquito," can transmit dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito was first colonized California in 2013 and arrived resistant to pyrethroids. "The pyrethroid target site genotype differs geographically in California and partially infers resistance phenotype, indicating that other mechanisms are at play as well."
"Since their detection in 2013, Aedes aegypti has become a widespread urban pest in California," the co-authors wrote in the abstract. "The availability of cryptic larval breeding sites in residential areas and resistance to insecticides pose significant challenges to control efforts. Resistance to pyrethroids is largely attributed to mutations in the voltage gated sodium channels (VGSC), the pyrethroid site of action. However, past studies have indicated that VGSC mutations may not be entirely predictive of the observed resistance phenotype."
"To investigate the frequencies of VGSC mutations and the relationship with pyrethroid insecticide resistance in California, we sampled Ae. aegypti from four locations in the Central Valley, and the Greater Los Angeles area. Mosquitoes from each location were subjected to an individual pyrethrum bottle bioassay to determine knockdown times. A subset of assayed mosquitoes from each location was then analyzed to determine the composition of 5 single nucleotide polymorphism (SNP) loci within the VGSC gene."
The conclusion:
"Resistance associated VGSC SNPs are prevalent, particularly in the Central Valley. Interestingly, among mosquitoes carrying all 4 resistance associated SNPs, we observe significant heterogeneity in bottle bioassay profiles suggesting that other mechanisms are important to the individual resistance of Ae. aegypti in California."
Mack, who holds a bachelor of science degree (2018) in biology from Creighton University, Omaha, Neb., enrolled in the UC Davis graduate school program in 2018.
Active in the Entomological Society of America, Mack scored second place in student competition at the 2022 joint meeting of the Entomological Societies of America, Canada, and British Columbia, held last November in Vancouver, British Columbia. She entered her presentation, "Three Dimensional Analysis of Vitellogenesis in Aedes aegypi Using Synchrotron X-Ray MicroCT,” in the category, "Graduate School Physiology, Biochemistry and Toxicology: Physiology.
Her abstract: "Traditional methods of viewing the internal anatomy of insects require some degree of tissue manipulation and/or destruction. Using synchrotron-based x-ray phase contrast microCT (pcMicroCT) avoids this issue and has the capability to produce high contrast, three dimensional images. Our lab is using this technique to study the morphological changes occurring in the mosquito Aedes aegypti during its reproductive cycle. Ae. aegypti is the primary global arbovirus vector, present on all continents except Antarctica. Their ability to spread these viruses is tightly linked with their ability to reproduce, as the production of eggs in this species is initiated by blood feeding. Amazingly, this species produces a full cohort of eggs (typically 50-100) in just 3 days' time following a blood meal. This rapid development represents dramatic shifts in physiological processes that result in massive volumetric changes to internal anatomy over time. To explore these changes thoroughly, a time course of microCT scans were completed over the vitellogenic period. This dataset provides a virtual representation of the volumetric, conformational, and positional changes occurring in tissues important for reproduction across the vitellogenic period. This dataset provides the field of vector biology with a detailed three-dimensional internal atlas of the processes of vitellogenesis in Ae. aegypti."
"As for career plans, I am applying to computational biology positions in industry," Mack said. "I'm not filing my dissertation until July so I am still working on this."
- Author: Kathy Keatley Garvey
Winokur delivered her presentation on “Thermal Preferences of Aedes aegypti Mosquitoes.”
Her abstract: “Mosquito-borne pathogen transmission models used to inform control decisions are only applicable if we incorporate the temperatures mosquitoes experience. However, mosquito thermal preferences are not well resolved. We studied Aedes aegypti thermal preferences and found that female Ae. aegypti generally avoided temperatures >30°C on a gradient in the lab, and chose relatively cooler microhabitats in the field as ambient temperature increased. Incorporating these preferences could improve the accuracy of transmission models for Ae. aegypti-borne viruses.”
The Hollandsworth Prize memorializes Gerald Hollandsworth, a past president of the West Central Mosquito and Vector Control Association.
A UC Davis alumna, Winokur received her doctorate in entomology, with a designated emphasis in the biology of vector-borne diseases, in November 2022, studying with Professor Barker of the Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine.
She delivered her exit seminar, as part of the UC Davis Department of Entomology and Nematology weekly seminars, in October on "Temperature Drives Transmission of Mosquito-borne Pathogens: Improving Entomological Estimates for Aedes aegypti-borne Virus Transmission Risk."
"The mosquito Aedes aegypti is the primary vector of a range of viruses that cause a major burden on human health worldwide, including dengue, Zika, chikungunya, and yellow fever viruses," Winokur related in her abstract. "As the Zika epidemic emerged in 2016, estimates for Zika risk were based on proxy evidence from closely related dengue virus. To improve risk estimates, we studied how temperature affects Zika virus extrinsic incubation period. We sought to further improve risk estimates by studying thermal preferences of Ae. aegypti mosquitoes in the laboratory and in the field. Current mosquito-borne pathogen risk models primarily use temperatures from weather stations or thermal imagery as a proxy for the temperatures mosquitoes experience, however such approaches do not account for local environments or microclimates available to adult mosquitoes. Taken together, the results of these studies can be used to improve prediction of mosquito-borne pathogen risk and inform mosquito control decisions." (See information on the mosquito on the California Department of Public Health website)
As a postdoc in the Barker lab, Winokur is working with VectorSurv (https://vectorsurv.org/), and has a fellowship from Pacific Southwest Center of Excellence in Vector-Borne Diseases (https://pacvec.us/), working on "Enriching Practical Learning Resources for Entomological, Medical, and One-Health Curricula."
Olivia received her bachelor's degree in May of 2015 from Cornell University where she was an interdisciplinary studies major (environmental effects on human health). She enrolled in the UC Davis graduate program in 2016.
At UC Davis, Winokur served as the 2019-2020 president of the Entomology Graduate Student Association and as a 2020-2022 committee member of the UC Davis Entomology Diversity, Equity, Inclusion, & Belonging. She co-founded the Girls' Outdoor Adventure in Leadership and Science (GOALS) in 2017 and continues to serve in leadership roles. GOALS is a free two-week summer science program for high school girls and gender expansive youth from backgrounds underrepresented in STEM fields. They learn science, outdoors skills, and leadership hands-on while backpacking in Sequoia National Park.
- Author: Kathy Keatley Garvey
The seminar, set for 4:10 p.m., Pacific Time, will be virtual only, announced seminar series coordinator Emily Meineke, an urban landscape entomologist and assistant professor.
The Zoom link: https://ucdavis.zoom.us/j/95882849672.
His abstract: "Because they vector pathogens to humans, mosquitoes impact millions of people every year. The global strategy for the management of mosquito-borne diseases involves controlling vector populations, to a large extent, through insecticide application. However, vector-borne diseases are now resurgent, largely because of rising insecticide resistance in vector populations and the drug resistance of pathogens. In this context, the Vinauger Lab studies the molecular, physiological, and neural basis of mosquito behavior. We rely on a collaborative, integrative, and
multidisciplinary approach, at the intersection between data science, neuro-ethology, molecular biology, and chemical ecology. Our long-term goal is to identify targets to disrupt mosquito-host interactions and reduce mosquito-borne disease transmission."
On his website, Vinauger elaborates: "The ability of mosquitoes to detect, process, and respond to olfactory information emitted by their hosts can affect disease transmission. The magnitude of their responses to host and plant odors varies drastically throughout the day, but, despite their clear epidemiological relevance, the neural and molecular mechanisms acting at the circuit levels to control mosquito behavior remain to be determined. In the lab, we employ an interdisciplinary approach combining behavioral assays, electrophysiological recordings, transcriptomic analysis, and CRISPR/Cas9 gene editing, to characterize rhythms in odorant detection, perception, and olfactory behavior, thereby identifying the genetic basis of the temporal plasticity in mosquito-host interactions."
Molecular geneticist and physiologist Joanna Chiu, professor and vice chair of the Department of Entomology and Nematology and a Chancellor's Fellow, will serve as the host. "I have very high regard for Dr. Vinauger's integrative and multidisciplinary research into the biochemical and neurophysiological basis of insect behavior," Professor Chiu said. "His research program is innovative and rigorous, leveraging techniques in quantitative behavioral analysis, bioengineering, neurobiology, and computational methods to address exciting and important questions in mosquito biology and behavior."
The Vinauger lab "studies the molecular, physiological, and neural basis of mosquito behavior," according to its website. "We are a group of experimental biologists, relying on a collaborative, integrative, and multidisciplinary approach, at the intersection between data science, neuro-ethology, molecular biology, and chemical ecology. Our long-term goal is to identify targets to disrupt mosquito-host interactions and reduce mosquito-borne disease transmission."
The Vinauger lab's latest publication, "Visual Threats Reduce Blood-Feeding and Trigger Escape Responses in Aedes aegypti Mosquitoes," appears in the Dec. 9, 2022 edition of Scientific Reports.
The abstract:
"The diurnal mosquitoes Aedes aegypti are vectors of several arboviruses, including dengue, yellow fever, and Zika viruses. To find a host to feed on, they rely on the sophisticated integration of olfactory, visual, thermal, and gustatory cues emitted by the hosts. If detected by their target, this latter may display defensive behaviors that mosquitoes need to be able to detect and escape in order to survive. In humans, a typical response is a swat of the hand, which generates both mechanical and visual perturbations aimed at a mosquito. Here, we used programmable visual displays to generate expanding objects sharing characteristics with the visual component of an approaching hand and quantified the behavioral response of female mosquitoes. Results show that Ae. aegypti is capable of using visual information to decide whether to feed on an artificial host mimic. Stimulations delivered in a LED flight arena further reveal that landed Ae. aegypti females display a stereotypical escape strategy by taking off at an angle that is a function of the direction of stimulus introduction. Altogether, this study demonstrates that mosquitoes landed on a host mimic can use isolated visual cues to detect and avoid a potential threat."
Vinauger joined the Virginia Tech faculty in October 2017, after serving as a postdoctoral research associate at the University of Washington, Seattle. Educated in France, he received his bachelor of science degree in biology/biological sciences in 2006 from the University of Orléans; his master's degree in 2008 from the University of Tours, France; and his doctorate in 2011 from the University of Tours, Research Institute on Insect Biology.
The UC Davis Department of Entomology seminars are held on Wednesdays through March 15. (See schedule.) Eight of the 10 will be in-person in 122 Briggs Hall, and all will be virtual.
- Author: Kathy Keatley Garvey
The parallel, cluster-randomized, controlled trial revealed that a spatial repellent, currently under review by the World Health Organization (WHO), reduced human Aedes-borne virus infection by 34.1 percent.
“That is a significant statistical and public health reduction,” said Scott, an internationally recognized medical entomologist who retired from the UC Davis Department of Entomology and Nematology in 2015 but continues his scientific research on the ecology and epidemiology of dengue, a mosquito-borne viral infection transmitted mainly by A. aegypti. Dengue, one of the most rapidly increasing vector-borne infectious diseases, infects some 400 million people a year, with 4 billion people at risk annually.
The clinical study results mean that spatial repellents have “the potential to reduce a variety of vector-borne diseases, augment existing public health efforts, and can be an effective component in vector control intervention strategies,” Scott said.
The newly published research, “Efficacy of a Spatial Repellent for Control of Aedes-borne Virus Transmission: A Cluster-Randomized Trial in Iquitos, Peru,” appears in the Proceedings of the National Academy of Sciences (PNAS). The Bill and Melinda Gates Foundation funded the research in a grant to the University of Notre Dame (UND). Medical entomologist Nicole Achee, a research professor at UND, served as the project leader.
“To have shown a substantial public health impact at an endemic site, is rewarding,” said Scott, now a resident of Luck, Wis. “Our results provide valuable new data on mosquito control that will help to fill long-standing knowledge gaps and improve guidance for development of enhanced public health policy. Because literally billions of people around the globe are at risk of infection and disease from these viruses we are encouraged that results from our trial will contribute to improved health and well-being of so many people.”
Epidemiologist Amy Morrison, a 1996-2018 project scientist with the UC Davis Department of Entomology and Nematology and now with the UC Davis School of Veterinary Medicine's Department of Pathology, Microbiology and Immunology, served as the lead author of the PNAS paper. “This trial was the most logistically challenging field project I've ever participated in,” she said. “I led the field efforts in Iquitos, Peru where I have resided since 1998. Our research team continued to amaze me; they had to replace more than 20,000 products in more than 2,000 houses every 15 days and managed 80 percent coverage of participating houses. This type of vector control trial is very difficult to carry out so demonstrating protective efficacy is very gratifying.”
Achee said the Peru study outcomes “are a critical component to achieving our goals for supporting a WHO policy endorsement for spatial repellents. The reduction in Aedes-borne virus infection in at-risk participants seen in trial results have fundamentally contributed to the WHO encouraging further consideration for the use of this product class in public health worldwide. This is a historical milestone that was led by the UC Davis implementing team and I am thrilled to have been part of the collaborative effort."
Spatial repellents are “devices that contain volatile active ingredients that disperse in air,” the authors explained. “The active ingredients can repel mosquitoes from entering a treated space, inhibit attraction to human host cues, or disrupt mosquito biting and blood-feeding behavior and, thus, interfere with mosquito–human contact. Any of these outcomes reduce the probability of pathogen transmission.”
More than half of the world population is at risk for infection with viruses transmitted by Aedes mosquitoes, including include dengue, Zika, chikungunya, and yellow fever, the scientists wrote.
Vector interventions are needed for Aedes-borne viral (ABV) disease prevention “but their application is hindered by the lack of evidence proving they prevent infection or disease," they wrote. "Results from our ABV study will help guide public health authorities responsible for operational management and worldwide ABV disease control and incentivize new strategies for disease prevention.”
“The primary mosquito vector, Aedes aegypti, thrives in modern tropical urban environments. Despite decades of effort to control Ae. aegypti populations and prevent disease, the geographic range of illness and the viruses this mosquito transmits continue to expand,” they related. “Rigorously proven vector control interventions that measure protective efficacy against Aedes-borne viruses are limited to Wolbachia in a single trial in Indonesia and do not include any chemical interventions. Spatial repellents, a new option for efficient vector control, are designed to decrease human exposure to Aedes-borne viruses by releasing active ingredients into the air that disrupt mosquito–human contact and, thus, reduce the risk of human infection.”
The Iquitos trial is one of two trials recommended by WHO for assessing public health value and developing global health policy for the intervention class of spatial repellents. “Fully integrating vector control into Aedes-borne viral disease prevention programs requires quantitative guidance based on quantitative measures of the impact from each intervention component,” the authors wrote. “Ministries of Health, local to national governments, and nongovernmental organizations can use the Peru trial results as an evidence base for informed application of spatial repellents. Considering the growing public health threat from Aedes-borne viral disease, difficulties of developing vaccines against multiple viruses, and past poorly informed vector control failures, enhanced Aedes-borne viral disease prevention will benefit greatly from interventions, like the Peru trial, with proven public health value.
Thomas Scott. Scott, a member of three WHO committees and one of the world's Highly Cited Researchers for the third consecutive year, co-chairs a Lancet Commission that focuses on how prevention of viruses transmitted by Aedes mosquitoes. 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. Highly honored by his peers, Scott won the coveted Harry Hoogstraal Medal from the American Society of Tropical Medicine and Hygiene in 2018. He is a fellow of the American Society of Tropical Medicine and Hygiene, Entomological Society of America, and the American Association for the Advancement of Science. He holds bachelor and master's degrees from Bowling Green (Ohio) State University and a doctorate in ecology in 1981 from Pennsylvania State University.
Amy Morrison. Morrison, who holds a doctorate in public health from Yale University, with a concentration in epidemiology of infectious diseases, and a master's degree in public health from UCLA, has served as the principal investigator, co-principal investigator and a collaborator on a number of federally funded grants. She specializes in the epidemiology of tropical vector-borne diseases, with an emphasis on (1) arthropod vector ecology and dengue virus transmission dynamics and (2) spatial and temporal analyses using Geographic Information Systems.
As a project scientist, Morrison supervises multiple studies on A. aegypti and dengue virus transmission dynamics, including longitudinal cohort studies evaluating A. aegypti control interventions, and the role of human movement in dengue transmission dynamics in Iquitos, funded by National Institutes of Health, Military Infectious Disease Research Program and Bill and Melinda Gates Foundation. She is an active member of the American Mosquito Control Association, American Association for the Advancement of Science, Entomological Society of America, American Society of Tropical Medicine and Hygiene, and the Society of Vector Ecologists.
Nicole Achee. Achee is a research associate professor in the Department of Biological Sciences, UND, and holds a joint associate professor appointment in the Eck Institute for Global Health, UND. She worked as a medical entomologist in the international settings of Belize, Indonesia, Mexico, Nepal, Peru, South Korea, Suriname, Tanzania and Thailand. Her curriculum vitae includes principal investigator for large scale clinical trials in Peru and Indonesia. Both studies aimed “to generate evidence of the protective efficacy of spatial repellents for prevention of malaria and dengue human infections for use toward full World Health Organization public health policy recommendations,” she says on her website. Achee holds a doctorate in medical entomology from the Uniformed Services University of the Health Science, Bethesda, Md.
In addition to the Bill and Melinda Gates Foundation, the Iquitos project drew support from the Defense Threat Reduction Agency, Military Infectious Disease Research Program and the U.S. National Institute of Allergy and Infectious Diseases.