Many biological processes and behaviors in mosquitoes display rhythmic patterns, allowing for fine tuning to cyclic environmental conditions. In mosquitoes, vector-host interactions are primarily mediated by olfactory signals. Previous studies have established that, in the malaria vector Anopheles gambiae, rhythmic expression of odorant binding proteins and takeout proteins in the antenna resulted in a corresponding rhythm in olfactory sensitivity to relevant host odors. However, it remained unclear how rhythms observed in olfactory sensitivity affect or explain rhythms in behavioral output, which ultimately impacts disease transmission. In order to address this knowledge gap, we quantified and compared patterns in locomotor activity, olfactory sensitivity, and olfactory behaviors in adult female Aedes aegypti mosquitoes. Here, we demonstrate an odorant-specific modulation of olfactory sensitivity in Ae. aegypti, decoupled from rhythms in olfactory behavior. Additionally, behavioral assays performed herein represent the first evidence of a time-dependence of the olfactory activation of behavior in Ae. aegypti mosquitoes. Results suggest that olfactory behavior of Aedes mosquitoes is modulated at both the peripheral (antenna) and central levels. As such, this work serves as a foundation for future studies aimed at further understanding the neural and molecular mechanisms underlying behavioral plasticity.

Sleep is a phenomenon conserved across the animal kingdom, where studies on Drosophila melanogaster have revealed that sleep phenotypes and molecular underpinnings are similar to those in mammals. However, little is known about sleep in blood-feeding arthropods, which have a critical role in public health as disease vectors. Specifically, sleep studies in mosquitoes are lacking despite considerable focus on how circadian processes, which have a central role in regulating sleep/wake cycles, impact activity, feeding, and immunity. Here, we review observations that suggest sleep-like states likely occur in mosquitoes and discuss the potential role of sleep in relation to mosquito biology and their ability to function as disease vectors.

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Aedes aegypti mosquitoes are the primary vector of disease‐causing viruses such as yellow fever, Zika, dengue fever, and chikungunya. With increasing insecticide resistance, novel control approaches informed by an improved understanding of mosquito biology are urgently needed to reduce vector‐borne disease transmission. Our research aims to further understand the molecular and physiological mechanisms that underlie mosquito‐host interactions. Female mosquitoes feed on warm‐blooded vertebrate hosts to obtain blood nutrients required for egg development, but are subjected to extreme thermal stress when feeding and, upon digestion of the blood, must cope with high levels of oxidative stress. Increased knowledge of the biological mechanisms mosquitoes use to cope with these stressors may have important epidemiological consequences for humans. Using next‐generation sequencing methods, we have characterized rhythmic daily variations in the global transcriptome of female Ae. aegypti heads, which encompass the visual and olfactory sensory appendages mosquitoes rely on to sense host‐seeking cues, the mouthparts, and tissues immediately exposed to blood stressors when feeding. Here we describe daily rhythms in mosquito host‐seeking and blood‐feeding stress tolerance. We also investigated daily rhythms in the metabolism of blood digestion, as these mechanisms represent targets of opportunity for mosquito control. Using state‐of‐the‐art respirometry methods to quantify rhythms in the metabolism of blood digestion in female Ae. aegypti mosquitoes, we were able to observe individual ventilatory patterns and compare the metabolic rates at rest and during digestion. These are the first measurements reported on carbon dioxide release from individual Ae. aegypti female mosquitoes and, thus, these results provide new insights regarding mosquito respiratory and metabolic physiology. Analysis of the metabolic rate following the ingestion of various diets additionally allows us to evaluate the effects of diet composition, oxidative stress exposure, and blood protein digestion on mosquito metabolism. Since this work can be used to identify novel vector control approaches targeting mosquito blood meal processing, our results will inform future efforts to decrease mosquito‐borne disease. Support or Funding Information USDA National Institute of Food and Agriculture, Hatch project 1017860. The Company of Biologists Journal of Experimental Biology Travelling Fellowship.

Aedes aegypti mosquitoes can be found globally in tropical and subtropical urban areas and spread Zika, Dengue fever, yellow fever, and Chikungunya viruses. Current vector control methods are limited and nonspecific. The female Ae. aegypti mosquito uses blood meal proteins to obtain nutrients required for oogenesis; inhibition of the midgut trypsin-like serine proteases responsible for blood meal digestion may provide a novel method of vector control. Ae. aegypti blood meal digestion is complex and the role of uncharacterized serine proteases in blood digestion is unclear; specifically, a group of trypsin-like serine proteases (AaSPII-V) is expressed at constant levels before and following Ae. aegypti blood meal acquisition. This research focuses on the in vitro biochemical study of two specific Ae. aegypti trypsin-like serine proteases (AaSPII and AaSPIV) in order to gain further understanding of their role in blood meal digestion. The approach involved the successful cloning and bacterial expression of these soluble, recombinant proteases. Results from attempts to purify these proteases were unsuccessful but indicative of potential autocatalytic and autodigestive behavior. Future studies will focus on obtaining purified recombinant proteases for further study. The study of AaSPII and AaSPIV, as well as other midgut Ae. aegypti proteases, will aid in understanding the overall role proteases play in blood meal digestion and may eventually allow for the development of mosquito-specific enzyme inhibitors. v ACKNOWLEDGMENTS First and foremost, I would like to thank Prof. Alberto A. Rascón Jr., my research advisor, for the opportunity to perform this research in his laboratory and for the expert mentorship and guidance I received throughout my research endeavors. While working with Prof. Rascón, I gained invaluable experience and learned both technical and practical skills to help me succeed in the future as a research scientist. I would also like to extend my gratitude to the members of my graduate committee, Prof. Laura Miller Conrad and Prof. Marc d'Alarcao, for their support and assistance in developing this thesis. I also thank my friends and colleagues at San Jose State University and in the Rascón Lab for the scientific discourse, encouragement, and laughter we've shared. For their constant love and support, I want to thank my family and friends. My mother and father, Valerie and Gregg Eilerts, have provided a lifetime of support and encouragement and prepared me for a successful future. I thank my brother, Tom Eilerts, for always making me laugh and for his endearing attempts to help me overcome research struggles via jelly donut metaphors. I thank my sister, Renee Eilerts, for always welcoming me in her home and making sure I remembered to occasionally have fun outside of the lab (Go Sharks!). I thank my best friend, Chelsea Carman, for listening and supporting me through both my undergraduate and graduate education. Lastly, I want to extend my deepest gratitude to my partner, Morgan Hoffman, for his unwaver...