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The Asian tiger mosquito, Aedes albopictus, transmits several arboviruses of public health importance, including chikungunya and dengue. Since its introduction to the United States in 1985, the species has invaded more than 40 states, including temperate areas not previously at risk of Aedes-transmitted arboviruses. Mathematical models incorporate climatic variables in predictions of site-specific Ae. albopictus abundances to identify human populations at risk of disease. However, these models rely on coarse resolutions of environmental data that may not accurately represent the climatic profile experienced by mosquitoes in the field, particularly in climatically heterogeneous urban areas. In this study, we pair field surveys of larval and adult Ae. albopictus mosquitoes with site-specific microclimate data across a range of land use types to investigate the relationships between microclimate, density of larval habitat, and adult mosquito abundance and determine whether these relationships change across an urban gradient. We find no evidence for a difference in larval habitat density or adult abundance between rural, suburban, and urban land classes. Adult abundance increases with increasing larval habitat density, which itself is dependent on microclimate. Adult abundance is strongly explained by microclimate variables, demonstrating that theoretically derived, laboratory-parameterized relationships in ectotherm physiology apply to the field. Our results support the continued use of temperature-dependent models to predict Ae. albopictus abundance in urban areas.

No abstract

Invasive mosquitoes are expanding their ranges into new geographic areas and interacting with resident mosquito species. Understanding how novel interactions can affect mosquito population dynamics is necessary to predict transmission risk at invasion fronts. Mosquito life‐history traits are extremely sensitive to temperature, and this can lead to temperature‐dependent competition between competing invasive mosquito species. We explored temperature‐dependent competition between Aedes aegypti and Anopheles stephensi, two invasive mosquito species whose distributions overlap in India, the Middle East, and North Africa, where An. stephensi is currently expanding into the endemic range of Ae. aegypti. We followed mosquito cohorts raised at different intraspecific and interspecific densities across five temperatures (16–32°C) to measure traits relevant for population growth and to estimate species’ per capita growth rates. We then used these growth rates to derive each species’ competitive ability at each temperature. We find strong evidence for asymmetric competition at all temperatures, with Ae. aegypti emerging as the dominant competitor. This was primarily because of differences in larval survival and development times across all temperatures that resulted in a higher estimated intrinsic growth rate and competitive tolerance estimate for Ae. aegypti compared to An. stephensi. The spread of An. stephensi into the African continent could lead to urban transmission of malaria, an otherwise rural disease, increasing the human population at risk and complicating malaria elimination efforts. Competition has resulted in habitat segregation of other invasive mosquito species, and our results suggest that it may play a role in determining the distribution of An. stephensi across its invasive range.

word count (max 250): 216 17 Text word count: 3753 18 ABSTRACT 30The Asian tiger mosquito, Aedes albopictus, transmits several arboviruses of public 31 health importance, including chikungunya and Zika. Since its introduction to the United States in 32 1985, the species has invaded over forty states, including temperate areas not previously at risk 33 of Aedes-transmitted arboviruses. Mathematical models incorporate climatic variables in 34 predictions of site-specific Ae. albopictus abundances to identify human populations at risk of 35 disease. However, these models rely on coarse resolutions of environmental data that may not 36 accurately represent the climatic profile experienced by mosquitoes in the field, particularly in 37 climatically-heterogeneous urban areas. In this study, we pair field surveys of larval and adult 38Ae. albopictus mosquitoes with site-specific microclimate data across a range of land use types 39 to investigate the relationships between microclimate, density of larval habitat, and adult 40 mosquito abundance and determine whether these relationships change across an urban 41 gradient. We find no evidence for a difference in larval habitat density or adult abundance 42 between rural, suburban, and urban land classes. Adult abundance increases with increasing 43 larval habitat density, which itself is dependent on microclimate. Adult abundance is strongly 44 explained by microclimate variables, demonstrating that theoretically derived, lab-parameterized 45 relationships in ectotherm physiology apply to the field. Our results provide support for the 46 continued use of temperature-dependent models to predict Ae. albopictus abundance in urban 47 areas. 48 49 cooler climates than Ae. aegypti. Following initial establishment in Texas, Ae. albopictus has 56 invaded over 40 states, 7 and models predict its range will expand as the climate warms. 8,9 At 57 present, established populations of Ae. albopictus are found in the United States as far north as 58Connecticut and New York, 10,11 well outside the present range of Ae. aegypti. Ae. albopictus is 59 implicated in transmission cycles of dengue and chikungunya in the Mediterranean region of 60 Europe, 12,13 which suggests that temperate regions of the US may be similarly vulnerable. 61Given the potential role of Ae. albopictus in disease transmission, it is important to 62 understand what factors influence its abundance. Ae. albopictus is sensitive to variation in 63 temperature due to temperature-dependent life history traits such as development rates, 64 fecundity, and survival. [14][15][16] Climate or meteorological predictors are widely used in mechanistic 65 models and statistical models. [17][18][19][20][21][22] Models leverage these relationships to predict mosquito 66 presence, population growth rates, and abundances based on temperature metrics derived from 67 weather stations or remotely-sensed datasets. However, urban landscapes are composed of a 68 variety of land classes (e.g. residential, developed, vegetated), which vary in th...