- Author: Kathy Keatley Garvey
The seminar also will be on Zoom. A pre-seminar coffee will take place from 3:30 to 4:10 p.m. in 158 Briggs.
"Ants of the genus Dorymyrmex, the 'pyramid ants,' exhibit an intriguing distribution that is most concentrated not near the equator, but instead in dry temperate regions of the Americas, such as deserts, shrublands, and beaches, and including Davis, California," Oberski writes in her abstract. "Although these ants are common, widespread, and ecologically significant, their diversity and evolutionary history are still poorly understood. My dissertation research introduces Dorymyrmex to modern phylogenomics and concerted biogeographic study by integrating classic and cutting-edge approaches: I performed targeted genomics with UCEs, inferred Bayesian phylogenies and fossil-calibrated divergence dates, and also employed traditional methods like morphometrics and visual species description."
"My work (1) characterizes the major lineages of Dorymyrmex, which are morphologically diverse in the Neotropics but actively peciating (and superficially similar) in North America; (2) illustrates an intercontinental range expansion that occurred millions of years ago; and (3) characterizes the Nearctic fauna, nearly doubling the number of Dorymyrmex species in North America. Ultimately, this research contributes to our knowledge of both local biodiversity and global dispersal patterns, and reveals Dorymyrmex is a unique system for studying rapid evolutionary radiations."
"I've been fascinated by insects as long as I can remember," Jill said. "As a kid, I learned the names of the major taxonomic orders and created a small pinned collection, but I didn't realize it could be anything more than a hobby, so I shifted my sights toward becoming a medical doctor. But when I went to college, I met a professor who actually does study biodiversity and discover new arthropod species for a living. So after getting my start in research at Macalester College, and a year as an intern at University of Wisconsin-Madison, I started searching for suitable research programs across the country where I could train as a grad student doing those same things—biodiversity, evolution, and biogeography of insects or arachnids."
"I was open to almost any insect/arachnid study system because generally, the more I learn about a group, the cooler I find it, and that turned out to be very true for ants. They're amazing little underappreciated creatures with societies all their own, and I'm so happy to be a myrmecologist."
Oberski is a past president of the UC Davis Entomology Graduate Student Association, and served in leadership roles in the Girls' Outdoor Adventure in Leadership and Science (GOALS).
Oberski received a five-year Dean's Distinguished Graduate Fellowship award in 2017. In May of 2022, she was selected for a Professors for the Future Fellowship (PFTF) award, described by PFTF as "a year-long competitive fellowship program designed to recognize and develop the leadership skills of outstanding graduate students and postdoctoral scholars who have demonstrated their commitment to professionalism, integrity, and academic service. The program is designed to prepare UC Davis doctoral students and postdoctoral scholars for an increasingly competitive marketplace and a rapidly changing university environment." For her project, she recorded a series of interviews about mental and chronic illnesses and how they impact academic professional development.
Oberski, who plays tenor saxophone at community events, performed in an entomology band at the 2018 UC Davis Picnic Day as Jill “Jillus Saximus” Oberski. She dressed as a “generalized heteropteran,” which she described as “most likely a member of the family Acanthosomatidae (shield bug) or Pentatomidae (stink bug). My family and friends have called me Jillybug, so I came to be the band's representative of Hemiptera.” (See news story on Entomology website, and feature in Entomology Today, published by ESA)
Future plans? After receiving her doctorate on June 15 in a UC Davis ceremony, Oberski will be moving to Washington, D.C. this summer for a brief stint as a visiting researcher at the Smithsonian Museum of Natural History. Then, in January 2024, she will start a three-year independent postdoctoral research position in Frankfurt, Germany.
The Oberski seminar is the last of the spring seminars, all coordinated by urban landscape entomologist Emily Meineke, assistant professor. For technical issues regarding Zoom connections, she may be reached at ekmeineke@ucdavis.edu.
- 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
Postema studies the role of animal coloration in predator-prey interatctions with a special focus on color-changing species. She works with both live and artificial swallowtail caterpillars (family Papilionidae) in the field.
She is the lead author of a review article, "Color Under Pressure: How multiple Factors Shape Defensive Coloration," published in June 2022 in the journal, Behavioral Ecology.
The abstract: Behavioral ecologists have long studied the role of coloration as a defense against natural enemies. Recent reviews of defensive coloration have emphasized that these visual signals are rarely selected by single predatory receivers. Complex interactions between signaler, receiver, and environmental pressures produce a striking array of color strategies—many of which must serve multiple, sometimes conflicting, functions. In this review, we describe six common conflicts in selection pressures that produce multifunctional color patterns, and three key strategies of multifunctionality. Six general scenarios that produce conflicting selection pressures on defensive coloration are: (1) multiple antagonists, (2) conspecific communication, (3) hunting while being hunted, (4) variation in transmission environment, (5) ontogenetic changes, and (6) abiotic/physiological factors. Organisms resolve these apparent conflicts via (1) intermediate, (2) simultaneous, and/or (3) plastic color strategies. These strategies apply across the full spectrum of color defenses, from aposematism to crypsis, and reflect how complexity in sets of selection pressures can produce and maintain the diversity of animal color patterns we see in nature. Finally, we discuss how best to approach studies of multifunctionality in animal color, with specific examples of unresolved questions in the field."
On the Yang lab website, Postema says: "After growing up in Ann Arbor, MI, I relocated to Denison University in Granville, OH to pursue my undergraduate degree. Though I began my college career as a studio art major, I quickly found that biology was my calling. I studied a wide range of systems throughout college, from lemon sharks and rock iguanas to deciduous shrubs. I am now conducting research on insect color and behavior in the Animal Behavior program at UC Davis. When I'm not obsessing over bugs, I can usually be found spoiling my pet chickens, drawing sketches for The Ethogram, or writing poetry."
At UC Davis, Postema is a member of the Animal Behavior Graduate Group.
"Elizabeth will be starting a great postdoc position studying beetle coloration at the Field Museum in Chicago," Professor Yang announced.
- Author: Kathy Keatley Garvey
His presentation also will be virtual. The Zoom link:
https://ucdavis.zoom.us/j/95882849672.
Zach, a member of Professor Phil Ward's laboratory, says in his abstract: "Ants belonging to the subfamily Leptanillinae (Hymenoptera: Formicidae) are sister to nearly all other extant Formicidae. Miniscule and subterranean, little is known of them. Contrary to the collecting bias observed in most Formicidae, male leptanilline specimens are acquired more easily than workers or queens. The sexes are almost never collected together, and certain groups are known from males only—some of these being so bizarre as to not resemble ants at all. These restrictions obstruct our understanding of evolutionary relationships among the Leptanillinae."
"My thesis is aimed at leptanilline taxonomy that reflected phylogeny and integrated morphological data from both sexes. I here present the culmination of this work, reliant on phylogenomic inference from ultra-conserved elements (UCEs), supplemented by total-evidence inference from male morphological data and UCEs. I also here summarize my exploration of leptanilline male genital skeletomusculature, a surreal vista illuminated by micro-computed tomography, in collaboration with Ziv Lieberman and others."
Griebenow will be filing his dissertation before May 19. He joined the Ward lab in September 2017. He holds a bachelor of science degree (2017) in agriculture (entomology) from The Ohio State University. He graduated magna cum laude. He minored in music.
Griebenow was a member of the UC Davis Linnaean Games team (now renamed Entomology Games) that won two national championships (2018 and 2022) at the Entomological Society of America (ESA) meetings. He also was a member of Ohio State's Linnaean Games team that won second place in the 2017 national championship.
His publication list includes:
Griebenow, Z. H., Isaia, M., and Moradmand, M. (2022). Discovery of a troglomorphic ant (Hymenoptera: Formicidae: Leptanillinae: Yavnella laventa sp. nov.) in southwestern Iran, with the first description of the worker caste of Yavnella Kugler. Invertebrate Systematics, 36, 1118-1138.
Griebenow, Z. H. (2021). Synonymisation of the male-based ant genus Phaulomyrma (Hymenoptera, Formicidae) with Leptanilla based upon Bayesian total-evidence phylogenetic inference. Invertebrate Systematics, 35(6), 603-636.·
Griebenow, Z. H. (2020). Morphological and phylogenomic delimitation of tribes in the subfamily Leptanillinae (Hymenoptera: Formicidae), with a description of the male of Protanilla lini Terayama, 2009. Myrmecological News, 30, 229-250.
Department seminar coordinator is urban landscape entomologist Emily Meineke, assistant professor. For technical issues (Zoom), she may be reached at ekmeineke@ucdavis.edu. (See complete list of spring seminars.)
- Author: Kathy Keatley Garvey
https://ucdavis.zoom.us/j/95882849672.
His title: "Using Genomic Data to Understand and Prevent the Spread of Tuta absoluta." He will be introduced by Chiu, professor and vice chair, UC Davis Department of Entomology and Nematology. A pre-seminar coffee will take place from 3:30 to 4:10 in Briggs 158.
T. absoluta, a species of moth in the family Gelechilidae, is a pest of tomato crops in its larval stage. It is also known as a tomato leafminer.
"Tuta absoluta is a serious agricultural pest of tomato plants," Lewald says in his abstract. "While initially discovered in Peru, it has rapidly invaded tomato fields around the world over the past century, causing widespread damage to the industry. The recent affordability of whole genome sequencing of insects opens the door to a wide number of applications to understand and control this pest."
"Using long read sequencing, we produced and annotated a highly contiguous T. absoluta genome assembly. Sequencing of individuals collected across many locations in Latin America allowed us to investigate population structure and diversity levels, as well as identify divergence times and possible migration events occurring between regions. Understanding these historical events can be key to predicting and preventing future invasion events. We also used comparative genomics between morphologically similar gelechiid species to develop efficient molecular diagnostics, allowing field researchers and stakeholders to identify Tuta absoluta rapidly to support quarantine and treatment efforts."
Lewald's research interests include studying population genetics and developing molecular diagnostics of pest insects. He received his bachelor's degree in molecular and cell biology from UC Berkeley in 2016. After studying circadian rhythms in sorghum with UC Berkeley professor Frank Harmon, he became interested in animal clock systems and joined the Chiu Lab in 2018.
He has published his work in several journals:
- Lewald, K. M., A. Abrieux, D. A. Wilson, Y. Lee, W. R. Conner et al., 2021 Population genomics of Drosophila suzukii reveal longitudinal population structure and signals of migrations in and out of the continental United States. G3 Genes|Genomes|Genetics jkab343.
- Lewald, K. M., and J. C. Chiu, 2020 Harnessing Transcriptomics to Study Insect Biology, in Transcriptomics in Entomological Research, CABI, Oxfordshire, UK.
- Tabuloc, C. A., K. M. Lewald, W. R. Conner, Y. Lee, E. K. Lee et al., 2019 Sequencing of Tuta absoluta genome to develop SNP genotyping assays for species identification. Journal of Pest Science.
- Gao, J., J. Sasse, K. M. Lewald, K. Zhalnina, L. T. Cornmesser et al., 2018 Ecosystem Fabrication (EcoFAB) Protocols for The Construction of Laboratory Ecosystems Designed to Study Plant-microbe Interactions. JoVE 57170.
The UC Davis Department of Entomology and Nematology's winter seminars are held on Wednesdays at 4:10 p.m. in 122 Briggs Hall. All are virtual. A pre-seminar coffee is held from 3:30 to 4:10 p.m. in 158 Briggs. Urban landscape entomologist Emily Meineke, assistant professor, coordinates the seminars. (See schedule.) She may be reached at ekmeineke@ucdavis.edu for technical issues.
