- Author: Kathy Keatley Garvey
Alarm bells went off. Scientists joined forces to target the mosquito and stop it from spreading throughout the state.
Enter the UC Davis laboratory of medical entomologist-geneticist Geoffrey Attardo, associate professor, UC Davis Department of Entomology and Nematology.
And now, enter the exit seminar of doctoral candidate Erin "Taylor" Kelly of the Attardo lab.
She'll present a seminar on "Investigating the Metabolic Underpinnings of Pyrethroid Resistance in California Aedes aegypti" at 3:30 p.m., Thursday, June 8 in 366 Briggs Hall and also on Zoom.
"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."
UC Davis medical entomologist Anthony Cornel, who leads the Mosquito Control Research Laboratory in Parlier, works with Taylor on insecticide resistance in mosquitoes. “Taylor's PhD project is challenging as she endeavors to tease apart the biochemical and genetic factors that cause resistance to some commonly used insecticides to control Aedes aegypti," wrote Cornel, a member of the UC Davis Department of Entomology and Nematology faculty. "Ae. aegypti is considered the second most dangerous insect worldwide because of its role in transmission of dengue, yellow fever, Zika and Chikungunya viruses which cause considerable morbidity and mortality. Hence, it is an important organism to study especially to eventually improve measures to control this mosquito."
Active in leadership activities and the Entomological Society of America, 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). She 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 highlights of her years pursuing a doctorate at UC Davis include:
- She 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.”
Kelly, 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.)
- Author: Kathy Keatley Garvey
Infected Ae. aegypti mosquitoes can transmit dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents.
Mack will present her exit seminar on "Genetic and Molecular Factors Influencing Pyrethroid Response in Aedes aegypti from California" at 3:30 p.m., Tuesday, June 6 in 366 Briggs Hall. It also will be on Zoom.
Mack studies Ae. 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 Ae. 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. 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."
Mack is the co-lead author (with doctoral candidate Erin Taylor Kelly of the Attardo lab) of Frequency of Sodium Channel Genotypes and Association with Pyrethrum Knockdown Time in Populations of Californian Aedes aegypti, published in March 2021 in the journal Parasites and Vectors. The eight co-authors, in additioin to Attardo, included Anthony Cornel, Mosquito Control Research Laboratory, Kearney Agricultural Center, and Department of Entomology and Nematology.
"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
Nematologist Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology, not only excels at research, teaching and public service but he serves as the coordinator of the department's weekly seminars for the 2021-22 academic year. And he's the host for many of the speakers as well.
Siddique, who holds a doctorate in agriculture and biotechnology from the University of Natural Resources and Life Sciences, Vienna, Austria, joined the UC Davis faculty in March 2019 (see news story), after serving as a research group leader for several years at the University of Bonn, Germany.
The fall quarter seminars just ended, and the winter quarter seminars will begin Jan. 5 and continue through March 9. They take place on Wednesdays at 4:10 p.m. in 122 Briggs Hall, located off Kleiber Hall Drive. The topics range from alfalfa weevil to the yellow-fever mosquito.
"Both in-person and virtual seminars will be broadcast via Zoom at https://ucdavis.zoom.us/j/
The schedule:
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
Jan. 26, 2022
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 species has spread to at least seven counties in California since June 2013, says UC Davis medical entomologist Anthony Cornel of the UC Kearney Agricultural Research and Extension Center, Parlier, and the UC Davis Department of Entomology.
“It's an issue of great concern, especially as current control methods do not appear to be working well," says Cornel, who collaborates on research projects in Clovis, Fresno County, with the Consolidated Mosquito Abatement District. The district, based in Fresno, covers 1,058 square miles, including part of Kings County.
“We can't predict how far this mosquito will go in California,” he says, but it has spread “south of Fresno to San Diego. The furtherest site north is Madera in the Central Valley, but it's also been found in the more coastal area of Menlo Park in San Mateo.”
As far north as Sacramento?
“I don't want to exclude the possibility that it may spread as far north as Sacramento,” said Cornel, who collects, rears and researches mosquitoes from all over the world, including the United States, Mali, Cameroon, Comoros, Tanzania, South Africa and Brazil. “We need to see if it overwinters as eggs or adults or both.”
Infected Aedes aegypti can transmit dengue, yellow fever, Zika and chikungunya viruses. The Zika virus was first identified in Uganda in 1947 in rhesus monkeys, according to the World Health Organization. It was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.
Although the mosquito species is in California, it's important to point out that there are no reported cases of locally transmitted Zika virus in the state or in contiguous United States, according to the Centers for Disease Control and Prevention. The cases have all involved travelers returning home from countries plagued with disease outbreaks.
Cornel and his colleagues published a 27-slide document, “Surveillance and Control of Aedes aegypti Mosquito in Clovis, Calif.,” on Feb. 8 in F1000 Research, http://f1000research.com/slides/5-149. They called attention to the widespread invasion and establishment of the species in California. The research, illustrated with maps, is the work of Cornel and Yoosook Lee of UC Davis; Stephen Dobson of the University of Kentucky; Corey Bansfield of MosqMate Inc. and Jodi Holeman, Mark Amireno, Charles Smith and Stephen Mulligan III of the Consolidated Mosquito Control District.
The California team collaborates with University of Kentucky scientists to develop novel control strategies. One trial involves coating male mosquitoes with insect growth regulators, which are passed on to the females. Males are also infested with a biopesticide or “a good bacteria-like organism,” Wolbachia. “The male transfers it to the female, which affects the ovaries and negatively affects immature development,” Cornel explains. “It's not new, but it's not been employed in large trials.”
The researchers target mosquito breeding sites, primarily yard drains. “Despite the drought and the elimination of visible bodies of water, such as bird baths, pet bowls and flower pots, there's a major issue: yard drains,” Cornel says. “Yard drains installed in new home developments empty into the gutter or street and are cryptic breeding sites for mosquitoes.” He speculates that these mosquitoes are breeding underground.
“These drains are not easily accessible and we can't see the mosquitoes,” Cornel points out. “We need to blow out the water and plug these yard drains to eliminate these breeding sites.” He suggests that cities everywhere address this public safety issue and “redesign the yard drains.”
It's crucial for the public to become involved, Cornel emphasizes. “We have to focus on public education. We have to get the message across to eliminate mosquito breeding sites. We can't go to every house. We must rely on the public to eliminate the breeding sites.”
It's possible—but he hopes not—that what is now a “mosquito nuisance” will result in a disease outbreak.
