Development of strains and procedures for genetic control of Aedes aegypti (Diptera: Culicidae)

Thesis

The mosquito Aedes aegypti is responsible for 50 million dengue fever infections in humans each year. A novel control strategy, named RIDL (Release of Insects carrying a Dominant Lethal) relies on releasing large numbers of genetically sterile male insects in order to control pest populations. This thesis describes the development of new tools to improve the efficiency of RIDL against Ae. aegypti and assessment of candidate strains for field release. Chapter 3 describes a new selection system for Ae. aegypti based on ethanol susceptibility conferred by the alcohol dehydrogenase gene (Adh) from Drosophila melanogaster. I observed that the susceptibility of Ae. aegypti larvae to ethanol can be triggered by expression of Adh in larvae. Chapters 4 and 5 focus on RIDL strains with a genetic sexing mechanism, for easy and stringent selection for males before mass-releases, eliminating disease- transmitting females. In Chapter 4, I describe the creation of a late-acting sexing strain of Ae. aegypti based on the Ae. aegypti doublesex (Aedsx) alternative splicing system. In Chapter 5, I describe an attempt to create an early-acting sexing system. Killing the females of the release generation early would free space and resources for the production of males. This was done by combining the Adh gene and the Aedsx alternative splicing system described in Chapters 3 and 4. Chapter 6 reports the results of a comparison, in terms of quality and productivity, between an existing Ae. aegypti RIDL strain and a wild-type control. Results showed equivalent female quality and productivity between the two strains, while RIDL males were less fertile in comparison with wild-type males. RIDL eggs also seemed more susceptible to long- term storage. The results of this work show promise for development of novel RIDL strains that may be used in the field to control disease-transmitting mosquitoes.

Authors: Collado, A

• Publication date: 2013
• DOI: 10.5287/ora-2azem9zz0
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: sterile insect technique; Aedes aegypti; genetic sexing system; transgenics; fertility; fecundity
• Subjects: Genetics (life sciences); Biology; Transgenics