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Title: Chordotonal organ mechanosensory pathways as potential targets for the control of mosquito borne diseases
Author: Topping, M. P.
ISNI:       0000 0004 7964 7949
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2017
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Mosquito-borne infectious diseases are the cause of millions of deaths every year, with disease transmission inseparably linked with mosquito physiology and biology. Mechanosensory signalling plays an essential role in multiple parts of the mosquito life cycle, making it a potential target for insecticides. In spite of this, and the existence of several 'mechanotoxins', these pathways have so far not been exploited. My thesis examined the various aspects of mechanosensation-dependent insect behaviour, as well as the effect the chordotonal organ-specific compound pymetrozine had on these behaviours. Behavioural studies using Drosophila melanogaster, including competition assays and flight tests, were completed to investigate the impact of pymetrozine exposure. Exposure produced significant decreases in flight ability and male reproductive fitness. Drosophila melanogaster lines previously reported to have insecticidal resistance were exposed to pymetrozine to check for potential cross-resistance, with no pymetrozine resistance being found in any case tested. Three mosquito species were then studied in depth - Aedes aegypti, Anopheles gambiae and Culex quinquefasciatus. Using an already existing Drosophila auditory model, electrophysiological experiments were conducted to compare between different species and sexes. A considerable level of sexual dimorphism was found throughout, especially in the auditory nonlinearities associated with transducer gating. Energy and displacement gains with regards to the mechanical auditory system were approximated and the nerve response to different stimuli was investigated. Male and female responses to compound injection were also calculated. Pymetrozine exposure was found to lead to complete loss of ChO mechanosensory function in these three species, as well as two additional insecticidal resistant Anopheles gambiae lines. Mathematical modelling of pymetrozine was discussed, particularly with regards to control programmes. 'Mechanotoxins' have so far been vastly underutilised as both insecticides and as a tool to explore auditory systems. These compounds hold great potential as methods of insect control.
Supervisor: Albert, J. T. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available