The geographical distribution of mosquito-borne disease is highly correlated with temperature. However, the relationship between temperature and mosquito traits are non-linear and often poorly parameterized, making landscape-level prediction difficult. Additionally, spatial predictions typically rely on remotely sensed or weather station temperature data, which are recorded at a coarser scale than that experienced by mosquitoes. Urban landscapes, in particular, consist of a wide range of microclimates that are typically more heterogeneous than natural landscapes. This study aimed to explore how urban landscapes influence mosquito-borne disease dynamics, through their effects on mosquito life history and arbovirus infection within the mosquito
. We conducted a semi-field experiment using the invasive mosquito Aedes albopictus and dengue virus as a model system. Experiments were performed twice, in the summer and fall of 2016. Each experiment included the rearing of larval mosquitoes at rural, suburban, and urban sites across the study site, using these microclimates as a field-based “incubator”, and recording relevant microclimate data at each. These land use types were chosen based on the percentage of impervious surface in the surrounding area, a known cause of the urban heat island effect, and to contain the full range of microclimates across the urban landscape. Emerged mosquitoes were collected daily and pooled by age before being offered a dengue infected blood meal. We tested mosquitoes for dengue infection, dissemination, and infectiousness 21 days post infection.
Results/Conclusions: Mean temperatures were 7.4 ∓ 0.12 degrees C cooler in the fall, causing a 63.2% decrease in larval survival relative to the summer. Urban sites had lower survival in the summer and higher survival in the fall, compared to other land use types, most likely due to extremely high temperature maxima of urban sites in the summer. Mosquito infection and dissemination rates were also higher in the fall trial relative to the summer trial, however the proportion of infections resulting in infectious mosquitoes did not differ across season. Similarly, urban sites had lower infection and dissemination rates than the other land use types, but this failed to produce a net difference in the density of infectious mosquitoes. In general, increased temperatures led to increased mosquito survival and decreased infection rates, indicating potentially opposing impacts on overall disease dynamics. We then incorporate these differential, non-linear results of microclimate on mosquito and infection dynamics into a model of vectorial capacity, to estimate disease dynamics across the landscape.