Development and preparation of Aedes aegypti strains for the puropse of genetic population control

Abstract

Aedes aegypti is the primary vector of dengue fever, a disease with an estimated incidence of 390 million cases per year. Vector control methods, which are used to control the spread of this disease, are proving to be unsatisfactory at preventing the spread and increasing incidence of the disease. A novel species-specific vector control tool is currently being trialled as an alternative method to limit transmission. This method, termed self-limiting uses tetracycline repressible dominant gene constructs to elicit population suppression when transgenic mosquitoes are released into the field. This thesis examines self-limiting strain development and characterisation as well as developing a better understanding of the fitness costs and effects on released males. The lead Ae. aegypti strain, OX513A is characterised in preparation for global use while a novel male-selecting strain is taken through its initial selection criteria to determine its suitability to become a product. These two self-limiting strains are assessed to determine their fitness, as well as developing our understating of what the influential components of rearing are on released males fitness. The tetracycline analogue used to rear the transgenic strains is shown to have a significant effect on transgene suppression and population selection. Male body size is shown to significantly affect the mating competiveness of released males depending on the body size of the female being competed for. Finally novel field relevant fitness assays are developed to assess insect quality more rapidly, with a view to being used at the point of male release. In conclusion this thesis develops the understanding of self-limiting strains both in terms of phenotype and insect fitness. It highlights changes that should be made to the strain maintenance and mass production process to prevent laboratory population selection, as well as increasing the fitness and quality of the insects as they are released into the field.