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Sammanfattning

Host seeking in mosquitoes is primarily driven by olfaction, with host odours comprising blends of odorants. Closely related mosquito species display marked differences in the expression and function of genes hypothesized to be involved in regulating host seeking and discrimination. The two biotypes of Culex pipiens, hereafter called Pipiens and Molestus, demonstrate differential host preference, however little is known about the molecular mechanisms regulating this behaviour. This thesis provides novel insights into the genetic basis of host preference of the two biotypes by identifying and characterising the behaviour of laboratory and wild European populations, and by studying the differences in expression and function of antennal chemosensory genes correlated with the observed behaviour. Behavioural analysis of laboratory populations of Pipiens and Molestus, using a Y-tube olfactometer, demonstrate a difference in host preference between the biotypes. To identify chemosensory genes correlated with this differential host preference, antennal transcriptome analysis of behaviourally phenotyped mosquitoes was used to identify differences in expression of chemosensory genes, including odorant receptor genes (Paper I). Differences in host preference were also observed in wild populations of the biotypes and their hybrids, with the host preference of the mosquitoes varying across a latitudinal gradient in Europe, along with differences in their relative populations (Paper II). Finally, the identified odorant receptors, from Paper I, were functionally characterised via heterologous expression in HEK293 cells in a ligand-induced fluorescence assay. Only one odorant receptor responded, with four compounds present solely in human odours, eliciting a dose-dependent response. A comparative analysis of the 3D-predictive protein structures of the Or205 of both biotypes revealed differences in gene sequence and protein structure, which could explain the observed differences in receptor function (Paper III). Together, the studies in this thesis expand our understanding of the genetic mechanisms regulating host preference in the Cx. pipiens biotypes.

Nyckelord

Culex pipiens; Molestus; host preference; Y-tube olfactometer; antennal transcriptome; odorant receptor; field collections; functional characterisation; HEK293 cells; predictive protein modelling

Publicerad i

Acta Universitatis Agriculturae Sueciae
2026, nummer: 2026:17
Utgivare: Swedish University of Agricultural Sciences

SLU författare

UKÄ forskningsämne

Biokemi
Genetik och genomik

Publikationens identifierare

  • DOI: https://doi.org/10.54612/a.1jidm263qb
  • ISBN: 978-91-8124-214-0
  • eISBN: 978-91-8124-234-8

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/146012