Climate Change and Mosquitoes in Australia

A changing climate means mosquito populations will be impacted, with changes in distribution and behaviour potentially occurring quicker than expected. 

Mosquito numbers are greatly influenced by local weather conditions and climate change is clearly going to impact these conditions. As a result, mosquito numbers, distribution, behaviour, species present and disease levels are all likely to change in Australia, perhaps quite quickly.

Whilst climate change will result in differential changes in weather – some areas will get drier, some will get wetter – the temperatures will generally get warmer. With warmer temperatures the mosquito life cycle (and that of the diseases they carry) will also speed up. For example, Aedes aegypti (pictured above) completes its life cycle in around 40 days at 16°C but in only ten days at 36°C. Fecundity and survival rates also change with temperature, dropping off at the extremes.1 Not only will warmer temperatures mean faster life cycles and higher mosquito numbers, but the mosquito season is likely to last longer.

The change in distribution of mosquitoes will also change as they move into areas that were previously sub-optimal, and they can establish quite quickly. A study back in 2019 noted that in the preceding five years, Aedes aegypti had spread northward in the US at a rate of about 250 km per year and in Europe Aedes albopictus had spread at a rate of approximately 150 km a year,2 probably due to a combination of climate change and human-mediated spread.

With mosquitoes increasing their range and numbers, the threat of disease will increase. Indeed by 2050 it is estimated that A. aegypti and A. albopictus, which are vectors for many of the serious mosquito-borne diseases, are like to pose a threat to 49% of the world’s population. Here in Australia, Aedes aegypti, the key vector for Dengue fever, is primarily confined to tropical north Queensland. However, even with moderate climate change, the mosquito will spread and extend the Dengue risk zone down to Brisbane.

The main mosquito-borne diseases in Australia are currently Ross River virus, Murray Valley encephalitis and Kunjin virus (a local variant of the West Nile virus). These are not common viruses but surges in cases occur following periods of extended rain and the subsequent increase in mosquito numbers. Such diseases are likely to become more prevalent with a changing climate. It is also likely to make diseases currently not present in Australia or those which have only occasional outbreaks, such as Dengue, to become established.

With human-mediated spread of mosquitoes an additional concern in Australia, biosecurity at our ports and airports is critical. A recent government report highlighted that more than half of all exotic mosquitoes detected in the national vector monitoring program in 2022 were at Sydney Kingsford Smith Airport (14 out of 24 nationally). In 2021 there were just three detections in Sydney (out of 18 nationally). One of the interceptions was of Aedes aegypti, which can spread yellow fever and Dengue fever.

Across Australia, surveillance points exist around the first point of entry at airports and seaports, as well as in other designated areas, and incoming cargo is subject to inspection.

“Exotic mosquitoes tend to arrive in Australia via baggage and cargo containers carried in the holds of aircraft travelling primarily from Southeast Asian airports. They are also found as larvae in pooling water within imported goods, especially imported tyres and break-bulk equipment,” commented Dr Chris Locke, Deputy Secretary, Biosecurity and Compliance Group.

On detection of an exotic mosquito, containers are fogged with insecticide and a residual surface treatment is carried out. Treatments are then followed by extensive surveillance through trapping.

Pest managers can certainly help spot the presence of exotic mosquitoes by brushing up on their mosquito identification skills. However, the reality is that the spread of mosquitoes is inevitable, so pest managers should be prepared for an increasing demand for mosquito management services over the coming decade.


1 Marinho, R.A (2016). Effects of temperature on the life cycle, expansion, and dispersion of Aedes aegypti (Diptera: Culicidae) in three cities in Paraiba, Brazil. Journal of Vector Ecology. 41 (1): 1-10.

2 Kraemer, M.U.G et al. (2019). Past and future spread of the arbovirus vectors Aedes aegypti and Aedes albopictus. Nature Microbiology: 4: pages 854–863 Further reading: ‘Fighting the exotic mosquito menace’. Department of Agriculture, Fisheries and Forestry. June 2, 2023.