Understanding mosquito vectors and methods for their control

Mosquitoes spread diseases that shorten and worsen the lives of many people, chiefly children in poor countries, around the world. Since Ronald Ross' discovery at the end of the nineteenth century that mosquitoes transmit malaria, field entomologists have collected a great deal of information about mosquito ecology. Despite this tremendous effort, there still remain significant gaps in our knowledge of mosquito ecology, in part, reflecting the significant variation in mosquito ecology across species and geographies. The main aim of this thesis is an attempt to synthesise the substantial information that field entomologists have collected on mosquito lifespan. In Chapters 2 and 3, I conduct meta-analyses of the two predominant approaches used to estimate mosquito lifespan: mark-release-recapture experiments and female mosquito dissection-based studies, respectively. These analyses produce estimates of mosquito lifespan by species and genus, and more broadly, allow for an appraisal of these two experimental approaches. In Chapter 4, I describe a recently developed approach, known as near-infrared spectroscopy, which enables estimation of the age of individual mosquitoes, and then perform an in silico analysis to explore the use of this technology for estimating the average lifespan of wild populations of mosquitoes.
The emergence of mosquito resistance to the main insecticides used in vector control, along with the concerning recent discovery that the malaria parasites in Asia are becoming resistant to arteminisin - an important drug used to treat malaria - highlight the need for novel approaches to control disease transmission. Some recently-proposed approaches involve genetic modification of the mosquito vectors, for example, to render them incapable of acting as hosts for disease or to reduce their fecundity. In Chapter 5, I model the impact of a release of mosquitoes carrying a genetic construct known as a homing endonuclease, which has been constructed to bias the sex of mosquito offspring towards males, in computational environments that capture some facets of the real life landscapes where mosquito borne disease is rife.
About a century ago, the famous Italian Malariologist Giovanni Grassi declared that malaria was a "giant with clay feet"; reflecting the optimism, in some academic circles at the time, that eradication of this terrible disease would soon occur. Unfortunately, a century of often unsuccessful attempts to control and eradicate malaria, and other mosquito borne diseases, would follow Grassi's statement, meaning that this fight is likely to continue throughout the twenty-first century. We now know much more about mosquitoes and mosquito borne disease than we did a generation ago, but there is still crucial information that we do not. In this thesis, I argue that in order to make significant inroads to disease eradication, further research on mosquito ecology is crucial. Only when we better understand our unwitting mosquito foe, can we design and implement effective disease control measures that are so desperately needed in those most desperate parts of the world.

Keywords: Mosquito
Malaria
Mosquito lifespan
Vector biology
Mark-release-recapture
Epidemiology
Near infrared spectroscopy
Genetically modified mosquito
Advisor: Godfray, C
North, A