UC Davis

The world's foremost arboviral vector, Aedes aegypti, has recently been established in California, with detections in 28 of 58 counties as of 2023(Aedes Aegypti and Aedes Albopictus Mosquitoes, n.d.). This dissertation explores population dynamics within the state, and the biology of insecticide resistance mechanisms using populations derived from Greater Los Angeles, Fresno, and Tulare counties.In Chapter 1, we utilize genomic data to investigate the population dynamics of Ae. aegypti in California. We report evidence of multiple introductions into the state, with distinct genetic clusters identified. We investigate a specific hypothesis: that a population of Ae. aegypti detected in Exeter, CA, in 2014 was successfully eradicated, and the region was then reinvaded in 2017. We find evidence to support this hypothesis and posit that the region was reinvaded by a population from Southern California. This chapter also explores varying levels of resistance to pyrethroid insecticides, facilitated by mutations in the Voltage-Gated Sodium Channel (VGSC), a primary mechanism of resistance. Chapter 2 delves into a phenotypic comparison between the Rockefeller laboratory strain and wild California Ae. aegypti populations. By integrating lifespan, transcriptomic, and metabolomic data, we uncovered significant differences in metabolic pathways, particularly those related to oxidoreductase activity. Notably, we observed baseline differences in oxidative stress response, energy metabolism, and lipid profiles between the populations. Our findings suggest that larval nutrition and metabolic resistance to pyrethroids significantly impact mosquito physiology and longevity. Finally, Chapter 3 investigates metabolic shifts in response to pyrethroid (Deltamethrin) exposure in two Ae. aegypti populations with distinct genetic backgrounds collected from Los Angeles and the Central Valley. By examining metabolic changes in two near-wild populations, we identified significant alterations in amino acid, lipid, and nucleotide metabolism following exposure. This study highlights the rapidity and variability of metabolic responses to insecticides, underlining potential targets for novel synergists in mosquito control. Overall, this dissertation uses a diversity of tools to investigate the spread, genetic diversity, and insecticide resistance mechanisms in Ae. aegypti, with a focus on California's evolving situation. The findings advance our understanding of Ae. aegypti resistance biology, vector management, and suggest avenues for more targeted and effective mosquito control measures

 REFERENCES 1. Aedes aegypti and Aedes albopictus mosquitoes. (n.d.). Cdph.ca.gov. Retrieved November 2023, from https://www.cdph.ca.gov/Programs/CID/DCDC/pages/Aedes-aegypti-and-Aedes-albopictus-mosquitoes.aspx