Paton, R. S. | bioRxiv Science

bioRxiv2026

A faster incubation explains Usutu leading West Nile in temperate Europe

Usutu virus (USUV) is a mosquito-borne flavivirus that has recently expanded northwards in Europe and become endemic in the UK. USUV emergence often precedes the closely related West Nile virus (WNV), potentially reflecting differences in epidemiological parameters. One key parameter is the extrinsic incubation period (EIP), the time taken for a mosquito to become infectious after a blood meal. Here we present the first quantitative estimate of the temperature dependent EIP for USUV in the vector Culex pipiens molestus. We were able to quantify the shortening of the USUV EIP from 68.06 days (95% CrI: 38.62 to 141.04) at 17 {degrees}C to 12.35 days (95% CrI: 8.10 to 17.09) at 25{degrees}C. This was achieved by re-analysing laboratory data with a bespoke Bayesian model that accounted for important features of the experimental design. Under UK summer temperatures, the median EIP of USUV is 37.75% (95% CrI: 3.38 to 55.68) shorter than that of WNV, and the potential transmission season of USUV is both longer and geographically more extensive. Under RCP8.5 climate projections, WNV transmission suitability could match or exceed current USUV levels between 2055 and 2065, highlighting the future threat to the UK from emerging mosquito borne pathogens. Our findings support USUV as a precursor for WNV in Europe and provide a robust characterisation of a key epidemiological parameter of USUV, enabling accurate modelling of its transmission dynamics.

ecology↗

bioRxiv2019

The ecological and epidemiological consequences of reproductive interference between the vectors Aedes aegypti and Aedes albopictus

Vector ecology is integral to understanding the transmission of vector-borne diseases, with processes such as reproduction and competition pivotal in determining vector presence and abundance. The arbovirus vectors Aedes aegypti and Aedes albopictus compete as larvae, but this mechanism is insufficient to explain patterns of coexistence and exclusion. Inviable interspecies matings - known as reproductive interference - is another candidate mechanism. Here, we analyse mathematical models of mosquito population dynamics and epidemiology which include two Aedes-specific features of reproductive interference. First, as these mosquitoes use hosts to find mates, reproductive interference will only occur if the same host is visited. Host choice will, in turn, be determined by functional responses to host availability. Second, females can become sterilised after mis-mating with heterospecifics. We find that a species with an affinity for a shared host will suffer more from reproductive interference than a less selective competitor. Costs from reproductive interference can be \"traded-off\" against costs from larval competition, leading to competitive outcomes difficult to predict from empirical evidence. Sterilisations of a self-limiting species can counter-intuitively lead to higher densities than a competitor suffering less sterilisation. We identify that functional responses and reproductive interference mediate a concomitant relationship between vector ecological dynamics and epidemiology. Competitors with opposite functional responses can maintain disease where human hosts are rare, due to vector coexistence facilitated by a reduced cost from reproductive interference. Our work elucidates the relative roles of the competitive mechanisms governing Aedes populations and the associated epidemiological consequences.

ecology↗