This PhD opportunity is being offered as part of the LSTM and Lancaster University Doctoral Training Partnership. Find out more about the studentships and how to apply.
| Abstract | In the last 30 years the Asian tiger mosquito Aedes albopictus has undergone rapid range expansion. Originally from South-East Asia, the current species distribution extends near- globally throughout the tropics and subtropics and even into temperate regions including Europe and the United States. With climate change and ever-increasing global trade further spread seems inevitable. However, other than the evolution of frost-tolerant eggs the biological factors underlying Ae. albopictus’ incredible success are not well understood. This is especially true in Africa where establishment appears to have occurred recently (doi: 10.1016/S2214-109X(23)00046-3). During brief East-West then South-North opportunistic transectional sampling for Ae. aegypti in Ghana (Weetman, Facchinelli, Afrane-group; September 2025) we detected Ae. albopictus at higher latitudes than previously recorded (which was in some coastal areas, particularly around ports) in the country, at least as far north as the major city of Kumasi (sample processing is ongoing). Unlike Mali, where invasion followed the course of the Niger River, this appears to have been a land-based northward spread. To our knowledge no systematic surveillance for albopictus has been conducted in West Africa leaving its distribution unclear. Indeed the east of Ghana where the Volta River provides major northerly water courses has never been surveyed, which if the Malian situation is replicated could form an independent route for northward spread. With the exception of a forest in southern Ghana where immatures were found in traditional breeding sites (tree hollows, cut bamboo, water-holding leaves) our survey detected immature and emergent adult Ae. albopictus in breeding sites typical of Ae. aegypti (tyres, waste containers, water storage barrels). This is notable because, based on lab and semi-field studies outside of Africa, Ae. albopictus is thought to be a superior competitor to Ae. aegypti in the larval stages, raising the possibility of competitive replacement through ecological niche expansion into more urban environments by Ae. albopictus. The consequences of such a replacement process for disease transmission are unclear. Aedes albopictus is a competent vector of the same arboviruses as Ae. aegypti, even more so for chikungunya which underwent a mutation increasing its transmissibility by Ae. albopictus. However, it has typically been regarded as the secondary vector of dengue albeit one that has caused multiple outbreaks in locations such as Indian Ocean islands where Ae. aegypti is not present. Moreover, modelling work suggests that life history differences between the species along with competitive superiority may overcome Ae. albopictus’ lesser competence for dengue and make the species near equal in dengue vectorial capacity (http://www.parasitesandvectors.com/content/7/1/338). If this is the case, then potentially greater ecological plasticity of Ae. albopictus, couple with a northward expansion toward Burkina Faso, the dengue hotspot of Africa (https://www.afro.who.int/countries/burkina-faso/publication/dengue-who-african-region-situation-report-02-14-january-2024#:~:text=Burkina%20Faso%20continues%20to%20be,African%20region%20is%20being%20developed.), could have serious consequences for dengue transmission. In this project we propose to conduct systematic spatially-explicit ecologically-informed surveillance (doi: 10.1101/2025.06.13.655782; doi: 10.1016/j.crpvbd.2024.100208) for Ae. albopictus throughout Ghana, building on our recent pilot study data. Data will be used to build distributional maps including both presence-absence and abundance hotspots and to build comparative ecological niche maps for each Aedes vector species. Additional linked-work will involve landscape genetics of Ae. albopictus (using reduced representation sequencing) to understand corridors for migration and changes in genetic diversity and potential adaptations linked to the species’ spread. Laboratory work will involve development of West African Aedes discriminatory diagnostics (preliminary work underway at LSTM), which will be important for high-throughput sample processing, especially from forests where multiple species can be found. Interspecific larval competition assays (Ae. albopictus vs Ae. aegypti) will be conducted using different types of rainwater-filled containers to investigate if one species can outcompete the other in different conditions of larval densities and food availability. A final component of the laboratory work will involve comparative testing of biting aggressiveness of each Aedes vector species, sampled from contrasting environments (natural vs urban) and using the same experimental set-up investigation of WHO-recommended personal protectants (mosquito repellents such as DEET, Picaridin, IR235; transfluthrin emanator products) to which resistance is suspected, but untested in West African Aedes. |
| Where does this project lie in the translational pathway? | T1 - Basic Research |
| Methodological Aspects | Methodological aspects will include training in R and QGIS, laboratory techniques including DNA extraction, PCR, qPCR, genomic data analysis, field surveillance training, insecticide resistance testing, behavioural studies, interspecific larval competition assays. There are many quantitative aspects to this project including training in advanced spatial modelling (Sedda); genomic analysis, and diagnostic development (Weetman); rigoruous behavioural study development and analysis (Facchinelli); field surveillance and associated data processing, insecticide resistance and diagnostic testing (Afrane). |
| Expected Outputs | Owing to the novelty and topicality of the topic we expect that this project will generate high impact publications as well as producing actionable data for Aedes control in Ghana, and potentially other climatically-similar countries in West Africa. The project would also be conceptually linked to a much larger multi-country project (Wellcome Discovery award application for summer 2026 round) on the causes of the spread of Ae. albopictus in Africa (involving all supervisors) |
| Training Opportunities | Please see 10 above |
| Skills Required | Skills/aptitudes for student: experience with field work, especially in West Africa would be a distinct advantage. Good command of written and spoken English. Highly numerate though other skills can be gained through the MRes year and during PhD |
| Subject Areas | Malaria and other VBDs; NTDs |
| Key Publications associated with this project |
doi: 10.1016/S2214-109X(23)00046-3 (Weetman) doi: 10.1101/2025.06.13.655782 (Sedda, Weetman) doi: 10.1371/journal.pntd.0010059 (Weetman) doi: 10.21203/rs.3.rs-7407322/v1 (Afrane) doi: 10.1093/pnasnexus/pgad226 (Facchinelli) |