Biology subjects

Medlock, J. M.

Publications and source records attributed to Medlock, J. M..

5 recordsLinked to original sources

bioRxiv2026

Ecology of mosquitoes in Scottish wetlands and confirmation of Culex molestus and hybrids in Scotland

BackgroundThe recent spread of mosquito-borne pathogens and their vectors within Europe highlights the impact of climate change on vector-borne disease (VBD) distributions. Mosquito surveillance has been implemented in many European countries to monitor expansion of vector populations and VBDs, but ability to predict disease risk is constrained by geographic data gaps, particularly in northern areas. In the United Kingdom, wetland mosquito surveillance has been conducted extensively in England, with a knowledge deficit for Scotland. Here, we addressed this gap through a nationwide survey of mosquitoes at Scottish wetlands, with aims of 1) confirming the geographic distribution and environmental drivers of mosquito occurrence and abundance, and 2) identifying the presence of vector species of epidemiological concern, including the Culex pipiens molestus biotype, an important vector of emerging VBDs in mainland Europe. MethodsMonthly mosquito sampling was conducted between June and October 2023 at 22 sites across Scotland comprising six wetland types: coastal saltmarsh, wet grassland, wet woodland, reedbeds, ponds and blanket bog. Adult and larval populations were sampled using Biogents BG-Pro traps and larval dipping respectively. Microclimatic and hydrological variables were recorded at collection sites and used in generalised linear mixed models to identify predictors of mosquito presence and abundance. Results1951 adults (17 species/ groups) and 860 larvae (six species/ groups) were collected from wetlands over 183 and 164 sampling events respectively. Mosquitoes were widely distributed across the Scottish mainland including up to the northern coast, being found at all but one site. Several potential vector species including Culex pipiens s.l. and Anopheles claviger were common. Amongst the adult Culex pipiens s.l. specimens, approximately 8% were Culex pipiens biotype molestus or hybrid forms. Total mosquito abundance and that of key vector species were positively associated with temperature and rainfall. ConclusionsWe report the widespread distribution of mosquitoes in wetlands throughout Scotland, including potential vector species previously unconfirmed in Scotland. Predicted associations between mosquito abundance, rainfall and temperature indicate that climate change could favour mosquito populations in Scotland. Our results provide the first comprehensive description of mosquito ecology in Scotland, as required to update assessment of VBD risk under climate change.

ecology↗

bioRxiv2025

Mosquito Viromes in England and Wales Reveal Hidden Arbovirus Signals and Limited Ecological Structuring

Outbreaks of mosquito-borne viruses are increasing in temperate regions, with West Nile and Usutu viruses now established in wide regions across Europe, and both detected in the UK. Current surveillance strategies focus on targeted approaches which are well suited for monitoring established threats but limited in their ability to detect recently described or neglected viruses. High throughput sequencing (HTS) provides an unbiased alternative, allowing simultaneous identification of well-recognised and overlooked arboviruses, alongside insect-specific viruses (ISVs) that may modulate vector competence of the insects transmitting these pathogens. This study presents the first comprehensive virome survey of Culex mosquitoes in the UK, analysing populations collected from 93 sites across England and Wales through HTS and a systematic virus discovery pipeline. Across these sites, 41 distinct viral taxa were identified, including 11 novel species. Most viruses were rare or confined to a few sites, with only three detected in more than one third of sites, suggesting the absence of a broad conserved virome across populations. Within this diversity, three arbovirus-related lineages were detected: Hedwig virus (Peribunyaviridae), Umatilla virus (Sedoreoviridae), and Atherstone virus (Peribunyaviridae), the former two representing the first detections in the UK. These putative arboviruses were embedded in viral communities that showed minimal structuring by coarse land type but a modest decline in richness with latitude across rural sites, consistent with diversity gradients observed in other microbial systems. Together, these findings provide the first national-scale baseline of Culex mosquito-associated viral diversity in the UK, and demonstrate the value of metagenomic approaches in arbovirus preparedness.

microbiology↗

bioRxiv2025

The First Chromosome-Scale Genome Assembly for Dermacentor reticulatus: A Key Vector of Tick-Borne Pathogens of Public and Veterinary Health Importance in Europe

BackgroundDermacentor reticulatus is a key tick species across Europe and an established vector of multiple pathogens that affect both human and animal health. Despite its significant role in disease transmission, genomic data for this species remain limited. Here, we present the first chromosome-scale genome assembly of D. reticulatus, constructed using Oxford Nanopore long-read sequencing data. MethodsHigh molecular weight DNA was extracted from a female Dermacentor reticulatus collected in Devon, UK, and sequenced using Oxford Nanopore long-read technology. Genome assemblies were generated using both guided and unguided approaches, followed by repeat masking, gene prediction, and functional annotation. Genome completeness was assessed using BUSCO, and comparative, phylogenetic, and functional analyses were performed against other Dermacentor and tick species. ResultsThis chromosome-scale genome assembly revealed a repeat-rich genome, with approximately 61.9% of the total sequence consisting of repetitive elements. Benchmarking universal single-copy ortholog (BUSCO) analysis demonstrated strong genome completeness, with guided assembly (chromosome) achieving a score of 97.1%, closely matching those of related Dermacentor species. For comparison, unguided assembly (scaffold) yielded a BUSCO score of 96.7%. Gene annotation following repeat masking resulted in BUSCO completeness scores of 95.1% (guided) and 95.0% (unguided). Functional characterisation included Pfam domain assignment and Gene Ontology analysis. Additionally, we assembled the mitochondrial genome (15,103 bp), comprising 38 genes, providing further insight into D. reticulatus phylogenetic placement. ConclusionsThis genomic resource establishes a foundation for functional genomics, evolutionary studies and supports future research in vector biology and the control of tick-borne diseases.

genomics↗

bioRxiv2025

Detection of West Nile Virus via Retrospective Mosquito Arbovirus Surveillance in the United Kingdom

In March 2025, as part of on-going enhanced surveillance for mosquito-borne Orthoflaviviruses, West Nile virus (WNV) RNA was detected in two pools of female Aedes vexans collected in July 2023 in Nottinghamshire, England. Viral RNA detection was achieved via reverse transcription-qPCR. Sequencing and subsequent phylogenetic analysis of a 402 bp fragment indicated that the detections clustered with WNV lineage 1a. The exact origin of this virus remains unclear, but this finding indicates a historic WNV presence in the United Kingdom (UK). Surveillance has not provided evidence of further viral transmission to date.

molecular biology↗

bioRxiv2024

Transovarial transmission in field caught mosquitoes identifies a mechanism for the establishment of Usutu virus in a temperate country

Usutu virus (USUV) is an emerging zoonotic flavivirus in Europe, and the first zoonotic mosquito-borne virus to be confirmed in animal hosts in the United Kingdom (UK). Phylogenetic analysis of USUV in the three years following its initial detection in 2020 indicated that the virus is overwintering in the UK. In 2023, USUV was identified outside Greater London for the first time. Therefore, USUV should now be considered endemic within southeast England. Surveillance of avian hosts and mosquito vectors has been insufficient to elucidate the mechanism by which USUV has persisted through temperate winters. It is likely that mosquitoes play a significant role in facilitating the establishment of USUV in temperate areas, as is the case for related mosquito-borne viruses. Here we undertake enhanced targeted vector surveillance at the index site to investigate the role of mosquitoes in facilitating USUV establishment in the UK. Between 2021 and 2024 inclusive, we detected USUV in host-seeking adult female Culex pipiens s.l. (n = 8/554 pools), a key vector of the virus in Europe. During 2023, enhanced surveillance detected transovarial transmission of USUV in wild Cx. pipiens s.l. (n = 1/202 pools), by screening adults following captive rearing of mosquito larvae collected from the field. This is, to our knowledge, the first description of vertical transmission of USUV in an arthropod vector. Consequently, transovarial transmission should be considered a viable mechanism for the persistence of USUV in temperate areas. Our results highlight the importance of undertaking detailed vector surveillance, across life stages, to inform the epidemiology of vector-borne viruses.

microbiology↗