A Spanish laboratory is breeding and sterilising thousands of tiger mosquitoes to fight dengue fever and other diseases as climate change encourages the invasive species to spread across Europe. Using an electron accelerator, the regional government-funded Biological Pest Control Centre in Valencia sterilises and releases about 45,000 male mosquitoes every week so they can pair with females - whose bite transmits diseases among humans - and eventually reduce the overall mosquito population.
"It's a species that is becoming more common with climate change ... There is a favourable environment for its development for longer periods of time throughout the year and its populations are increasing all the time," said Vicente Dalmau of Valencia region's health, agriculture and fisheries department. The specimens for reproduction come from the region, and scientists then use a machine to separate female pupae from the males, before using radiation to sterilise the males.
Sterilisation techniques have been used in other parts of the world but the lab, using its experience with fruit flies, is pioneering their use on tiger mosquitoes in Europe at a time of growing concern over a rise in mosquito-born diseases such as dengue, zika and chikungunya. Data from the European Centre for Disease Prevention and Control shows an increase in cases imported from regions where dengue is endemic, as well as an increasing number of local outbreaks of West Nile virus and dengue in Europe.
The striped tiger mosquito, or Aedes albopictus, is spreading north, east, and west in Europe, and now has self-sustaining populations in 13 countries, including Spain. The World Health Organization said last year that dengue rates were rising globally, with reported cases since 2000 up eightfold to 4.2 million in 2022, as a warmer climate is thought to help the mosquitoes multiply faster.
The tiger mosquitoes appear to be spreading across the Balearics. Mallorca has already taken action in Palma but now in Menorca Ciutadella Town Hall has warned of the presence of the tiger mosquito in the municipality, and has informed the population of the main actions to be taken in terms of prevention. In a press release, the council has reminded the public that to avoid them spreading it is advisable to clean, empty, dry and renew the water in all containers in the vicinity, including pet drinking fountains or swimming pools, because the insect of Asian origin breeds in the aquatic environment, especially between the months of April and October.
Also, if a mosquito is identified, it is important to bear in mind that there is likely to be a breeding site in close proximity, as its flight range is only about 150 metres. On the other hand, for those facilities that cannot be emptied, such as fountains or swimming pools, periodic chlorination or treatment with larvicides is recommended, while in natural areas there are already predators such as sapsuckers and ‘granotes’.