Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Matthew DeGennaro,

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Aaron Mattfeld

Second Advisor's Committee Title

committee member

Third Advisor's Name

Fernando G. Noriega

Third Advisor's Committee Title

committee member

Fourth Advisor's Name

Jamie Theobald

Fourth Advisor's Committee Title

committee member

Fifth Advisor's Name

Mauricio Rodriguez-Lanetty

Fifth Advisor's Committee Title

committee member


Genetics, IR8a, Aedes aegypti, Mosquito, Olfactory receptors, CRISPR, attractive behaviors, Tethered flight, Visual cues

Date of Defense



Mosquitoes detect their hosts and seek suitable resources crucial for survival by integrating chemosensory, thermal, and visual cues. The diversity of the cues involved in mosquito attractive behaviors has made the design of behavioral control strategies a challenge. The genetic basis of mosquito attractive behaviors can now be determined using genome editing. The contribution of the IR8a chemosensory pathway was uncovered by disrupting the IR8a co- receptor in Aedes aegypti using CRISPR/Cas9. Ir8a mutant female mosquitoes are not attracted to lactic acid, a behaviorally active component of human sweat, and lack odor-evoked responses to acidic volatiles. The loss of Ir8a reduces mosquito attraction to humans and their odor. IR8a pathway indirectly mediates attraction to water, a crucial resource for oviposition and survival. Using tethered flight experiment, mosquitoes show robust visual tracking of inanimate object perfumed with carbon dioxide (CO 2 ) than fruit flies. Interestingly, CO 2 -insensitive Gr3 mutant mosquitoes exhibit impaired visuomotor reflex. This dissertation represents the first comprehensive evidence that the Ae. aegypti IR8a pathway mediates attractive behavior to human hosts and water source. The CO 2 -sensing pathway synergizes with the visual system to guide attractive behavior in Ae. aegypti mosquitoes. Understanding the molecular targets and the sensory cues that drive attractive behavior will provide insights to generate new behavioral control reagents.



Previously Published In

Raji, JI., Melo, N., Castillo, J., Gonzalez, S., Saldana, V., Stensmyr, M., DeGennaro, M. 2019. Aedes Aegypti Mosquitoes Detect Acidic Volatiles Found in Human Odor Using the IR8a Pathway. Current Biology 29, 1-10. Available at SSRN 3280246

Raji, Joshua I; Gonzalez, Sheyla; and DeGennaro, Matthew. (2019). Aedes aegypti Ir8a mutant female mosquitoes show increased attraction to standing water. Communicative & Integrative Biology, 12(1).

Raji, J. I and DeGennaro, M., 2017. Genetic Analysis of Mosquito Detection of Humans. Current Opinion in Insect Science 20: 34-38.



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