Fine-scale variation in microclimate across an urban landscape shapes variation in mosquito population dynamics and the potential of Aedes albopictus to transmit arboviral disease

Abstract

Most statistical and mechanistic models used to predict mosquito-borne disease transmission incorporate climate drivers of disease transmission by utilizing environmental data collected at geographic scales that are potentially coarser than what mosquito populations may actually experience. Temperature and relative humidity can vary greatly between indoor and outdoor environments, and can be influenced strongly by variation in landscape features. In the Aedes albopictus system, we conducted a proof-of-concept study in the vicinity of the University of Georgia to explore the effects of fine-scale microclimate variation on mosquito life history and vectorial capacity (VC). We placed Ae. albopictus larvae in artificial pots distributed across three replicate sites within three different land uses–urban, suburban, and rural, which were characterized by high, intermediate, and low proportions of impervious surfaces. Data loggers were placed into each larval environment and in nearby vegetation to record daily variation in water and ambient temperature and relative humidity. The number of adults emerging from each pot and their body size and sex were recorded daily. We found mosquito microclimate to significantly vary across the season as well as with land use. Urban sites were in general warmer and less humid than suburban and rural sites, translating into decreased larval survival, smaller body sizes, and lower per capita growth rates of mosquitoes on urban sites. Dengue transmission potential was predicted to be higher in the summer than the fall. Additionally, the effects of land use on dengue transmission potential varied by season. Warm summers resulted in a higher predicted VC on the cooler, rural sites, while warmer, urban sites had a higher predicted VC during the cooler fall season.

Meteorological Parameters and Mosquito Abundance in Pashan Area of Pune, India during South West Monsoon and Post-Monsoon Seasons in 2016

“…Carrington et al, in a study conducted in northwest Thailand have found that large diurnal temperature range (DTR) adversely affects mosquito biology by extending immature development phase, lowered larval survival and reduced female reproductive capacity (Carrington et al, 2013a). Our findings of mosquito abundance and DTR reinforce these findings along with those from a diversity of laboratory studies demonstrating the effects of DTR (Lambrechts et al, 2011;Carrington et al, 2013b;Carrington et al, 2013c;Liu-Helmersson et al, 2014;Murdock et al, 2017) on a variety of mosquito life history traits like survival, fecundity, larval development, biting rates, vector competence, and viral transmissions.…”

Thermal biology of mosquito‐borne disease

“…(8) Microclimates and habitats vary in temperature. While studies often focus on constant or mean temperatures, in the field vectors can preferentially occupy habitats with favourable microclimates (Paaijmans et al 2010b;Paaijmans & Thomas 2011b;Murdock et al 2017). How much do microhabitat availability and preferences moderate the effects of average temperatures on transmission?…”

“…Collect mosquitoes in their preferred resting and breeding habitats in the field. Experimentally measure traits in different microclimates in the field (Murdock et al 2017). Adapt mechanistic models to incorporate temperatures from relevant microclimates, rather than averages over larger spatial scales.…”

El Niño drought and tropical forest conversion synergistically determine mosquito development rate

“…It is possible that other microclimate factors may influence mosquito larval development. For example, relative humidity is expected to be greater in logged forest than in oil palm (Hardwick et al 2015), which could decrease the surface tension of water in the experimental pots (Pérez-Díaz et al 2012) and thereby impact mosquito pupation success (Murdock et al 2017). An alternative explanation for the absence of a land-use effect on development during the ENSO drought is that the elevated temperatures in the oil palm plantation were high enough to cause stress and reduce the fitness of developing mosquitoes (Feder and Hofmann 1999).…”