Climate change accelerating the spread of disease-carrying mosquitoes

Climate change is altering the living conditions of many species, and the common disease-carrying mosquito Aedes aegypti is no exception. A new study modeling the impact of rising temperatures on suitable habitats for these insects has found such regions are expanding at a steady rate, with the scientists warning the mosquitoes could become common in southern Europe within 10 years.

Aedes aegypti is a carrier of a range of diseases including dengue, zika and yellow fever, and primarily inhabits tropical and sub-tropical climates. But with human-generated carbon dioxide emissions driving global temperatures upward, scientists at Imperial College London and Tel Aviv University set out to gauge how climate change might be helping them spread over a much larger footprint.

The researchers began by analyzing how temperature can affect the mosquito at the egg, larvae, pupae and adult stages. These observations were then compiled into a singular “phenology model” to calculate how effectively the mosquito could complete full lifecycles in a given set of weather conditions.

Historical data and projections on world temperature and rainfall from 1950 to 2050 was then fed into the model, to investigate how effectively Aedes aegypti would be able to grow and reproduce in different locations. These projections were based on two climate change scenarios, one where significant cuts to emissions were made, and one where no action was taken at all.

Already, between 1950 and 2000, the world has become more suitable for Aedes aegypti at a rate of 1.5 percent per decade, according to the scientists. Were we to implement the emissions cuts factored into their model, this could still increase to 3.2 percent a decade by 2050. And under the business as usual scenario, this could increase by as much as 4.4 percent a decade.

“This work helps reveal the potential long-term costs of failing to curb greenhouse gas emissions right now,” says Dr Kris Murray from Imperial College London. “Our results show that this species of mosquito has very likely already benefitted from recent climate change across much of the world. But this increase in suitability is now also starting to accelerate. We predict that significant emissions cuts can help slow it down.”

According to the team’s calculations, our current emissions path will see the invasion frontiers of the Aedes aegypti mosquito advance by six kilometers (3.7 mi) a year by 2050, which is 3.5 times faster than historical figures. In Europe, the team says this rate of advancement could see parts of Spain, Portugal, Greece and Turkey offer “sustained suitability” for the insect by 2030.

“By translating biological knowledge from the laboratory into maps of environmental suitability through time, we think our approach can provide locally specific and policy-relevant insights for mosquito and possibly disease management under a changing climate,” says lead author Dr Takuya Iwamura from Tel Aviv University.

The research was published in the journal Nature Communications.

Source: Imperial College London