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Molecular characterisation and evolution of the sensory system inmosquitoes

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posted on 2025-02-04, 11:05 authored by Julien Devilliers

Mosquitoes are well studied for their human health importance, but the molecular mechanisms driving their behaviours remain poorly understood. In this thesis, we investigated molecular mechanisms driving host-seeking behaviour, blood-feeding and swarming. Blood-feeding behaviour evolved independently multiple times in dipterans, where hematophagy has been selected in females extracting needed energy for oviposition from the blood. Here, using phylogenomic analyses, we identified a convergent expansion of gene families in mosquitoes and sandflies, linked to the emergence of blood feeding behaviour. These gene families included a class of octopamine receptors involved in feeding behaviour, suggesting a common adaptation of those receptor in blood-feeding behaviour. Highlighting the lack of non-vector genomics data in mosquitoes, we then provided new reference genomes for the pitcher-plant mosquito (Wyeomyia smithii) and the Southern African elephant mosquito (Toxorhynchites brevipalpis). To investigate the differential involvement of sensory cues and integration between nonbiting males and biting females, we then performed single-cell RNA-sequencing in the head of the malaria mosquito (Anopheles gambiae). We found differential genes expressed in photoreceptor cells of adult mosquitoes suggesting sexually dimorphic temporal resolution of the visual system, as well as different modulation of auditory neurons. When focusing on the full eye of mosquitoes and comparing gene expression between males and females of a non-biting species and two vector species, we identified differential gene expression of olfactory-related genes. These results suggest that the strong interaction between the senses in mosquitoes might be processed directly in the sensory organs or first neuropils before further integration in the brain. Finally, we investigated the molecular mechanisms initiating swarming behaviour in Aedes aegypti, showing a contrasting involvement of the circadian clock compared to previous results in An. gambiae.

History

Supervisor(s)

Roberto Feuda; Ezio Rosato; Kyriacou Charalambos; Benjamin Warren

Date of award

2025-01-07

Author affiliation

Department of Genetics, Genomics and Cancer Sciences

Awarding institution

University of Leicester

Qualification level

  • Doctoral

Qualification name

  • PhD

Language

en

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