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Title: Mosquito (Diptera: Culicidae) biting behaviour and malaria transmission : interactions between intrinsic host preferences and local host availability
Author: Orsborne, James
ISNI:       0000 0004 9359 4142
Awarding Body: London School of Hygiene & Tropical Medicine
Current Institution: London School of Hygiene and Tropical Medicine (University of London)
Date of Award: 2020
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Distribution of mosquito-borne diseases is governed by a complex mix of genetic, environmental and social factors which in turn affect pathogen, vector and host interactions. Different mosquito species show a variety of host biting behaviours with some showing an extreme preference for human blood hosts. However, even the most anthropophilic vectors will source a proportion of their blood meals from nonhuman hosts, suggesting this preference is not fixed. This thesis investigates mosquito biting behaviour and the interactions between intrinsic host preference and host availability. Firstly, through investigation of the literature, the HBI was found to be more associated with collection location (R2 = 0.29) than mosquito species (R2 = 0.11). The influence of host availability was then tested in the field using a transect-based collection methodology. Anopheles mosquitoes were collected across a range of human host availabilities and significant changes in HBI (OR = 1.50 (95% CIs:1.05 – 2.16)) and BBI (OR = 0.60 (95% CIs:0.49 – 0.73)) were observed over 250 metres. In addition, extrinsic factors (AIC:243) impacted human blood host choice more than intrinsic factors (AIC:359.8). The transect-based collection strategy coupled with a novel molecular measure of blood meal digestion also informed mosquito dispersal. An. coluzzii was shown to typically remain within 50m of their host up to seven hours after feeding but disperse up to 250m after sixty hours. This novel molecular method was further optimised for multiple mosquito species of medical importance and compared to the Sella score, a widely used visual measure of blood meal digestion. This thesis provides compelling evidence of how host availability directly influencing mosquito host preference and describes a novel measure of dispersal utilising bloodmeal digestion. Understanding factors influencing host choice opens the opportunity to synergise current control efforts with alternative methods that exploit this behaviour, ultimately increasing the impact of current and future interventions.
Supervisor: Yakob, L. ; Walker, T. Sponsor: Medical Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral