Theses and Dissertations

Date of Award

8-1-2026

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Christopher Vitek

Second Advisor

Frank Dirrigl

Third Advisor

Ezzat El-Sherif

Abstract

Insecticide resistance has been documented across multiple insecticide classes in mosquito species worldwide. Aedes aegypti, commonly known as the yellow fever mosquito, is the primary vector for several arboviral pathogens such as Zika virus, dengue virus, and chikungunya virus. Although this species has been shown to exhibit insecticide resistance, precise mechanism driving insecticide resistance in south Texas is not yet characterized. Metabolic resistance is driven primarily by the overexpression of detoxification enzymes, including cytochrome P450 monooxygenases, glutathione S-transferases, and carboxylesterases. Two primary forms of expressed resistance have been documented on Ae aegypti, constitutive expression and induction. Constitutive expression occurs when the mosquito, through genetic amplifications, already maintains a high base level of these detoxification enzymes independent of any external stimuli. Induction occurs when physiological responses trigger these enzymes to overexpress, for example, through blood feeding. This study aimed to compare the influence of blood feeding on permethrin susceptibility and the expression of cytochrome P450 detoxification genes CYP9J28 and CYP9J32 on adult female Ae aegypti. Mosquitoes were tested using the Center for Disease Control and Prevention bioassay across three different time points post blood feeding: 3, 24, and 72 hours. Survival Analysis showed a significance between time post blood meal and treatment (p < 0.0001) with blood fed females (BF) showing significantly greater survival than non-blood fed females (NBF) at 72 hours post blood meal, confirming that blood feeding enhances insecticide tolerance. Gene expression was assessed using RT-qPCR.

Comments

Copyright 2026 Fernanda Martinez. All Rights Reserved. https://proquest.com/docview/3409003477

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