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Keywords:

  • Aedes aegypti;
  • breeding container;
  • climate;
  • thermal response;
  • water storage

Abstract

In Australia, the dengue vector Aedes aegypti is presently restricted to Queensland but was historically more widespread. Future spread may be facilitated by changes in the availability of suitable ovipositing sites (artificial containers) in response to climate change. We undertook a replicated comparison of thermal and hydric conditions in a selection of water containers commonly used by Ae. aegypti under sun and shade conditions in a tropical (Cairns) and temperate (Melbourne) location. We assessed the implications of thermal and hydric regimes for development rates and thermal stress. Container type had no effect on potential development rate in Cairns but mosquitoes in tyres were predicted to have consistently slower development than those in other containers in Melbourne. Our dataset included the hottest day on record for Melbourne (46.4°C) yet few containers exhibited lethal water temperatures in this location. Similarly high water temperatures were reached in Cairns at more benign air temperatures due to high solar radiation loads. The tyres had unique thermal profiles that exhibited a plateau at shaded air temperature even when in full sun. Overall, our results suggest that chronic cold stress would prevent development in Melbourne during spring, drying of containers would be limiting in Melbourne in summer, and heat stress in unshaded small containers would be limiting in Cairns. Tyres could be an important and unappreciated buffered habitat in open areas in the tropics. These results are of value for directing water storage and waste policy to prevent the further spread of Ae. aegypti and dengue fever as well as other mosquitoes. The methodology can be applied to identify priority containers for surveillance in other parts of the world.