Lorraine Williamson
In a move that sounds counterintuitive but is backed by science, Spain is releasing 28 million mosquitoes in a bid to dramatically reduce the spread of one of the country’s most aggressive and disease-prone pests: the Aedes albopictus, more commonly known as the tiger mosquito.
Rather than turning to pesticides or mass spraying, authorities are taking a smarter, safer route. They are unleashing waves of sterile male mosquitoes to outwit the insect at its own game.
A pest on the rise
The tiger mosquito, easily recognisable by its black-and-white striped body and notorious for its daytime bites, is no ordinary nuisance. Native to Southeast Asia, the species has surged across the Mediterranean in recent decades. This has been fuelled by warmer temperatures and expanding urban habitats.
Its bite is not just irritating – it’s potentially dangerous. This invasive insect is known to transmit several viral diseases, including dengue, zika and chikungunya. As such, the species has become a growing public health concern along Spain’s coastline, where humid conditions make ideal breeding grounds.
A strategy rooted in science
The initiative began in Elche, in Spain’s Alicante province, and is being rolled out to other towns and cities including Castelló de la Plana, Valencia, Torrent, Sagunto and Paterna. By 2026, the programme aims to have released 28 million sterile male mosquitoes across more than 300 hectares of vulnerable land.
These lab-reared males are incapable of producing offspring. Although they actively seek out female mosquitoes to mate with, the resulting eggs are infertile. Over time, this disrupts the breeding cycle and slashes the overall population.
It’s a method known as the Sterile Insect Technique (SIT), a concept that dates back decades and was once used successfully to control agricultural pests like the Mediterranean fruit fly. Now, it’s being applied to public health with a new twist.
The Wolbachia twist
Researchers at the University of Valencia have introduced a game-changing element to the campaign: a microscopic bacterium called Wolbachia, which is added to the mosquito eggs during the rearing process. When males carrying the bacterium mate with wild females, the resulting embryos fail to develop.
This double-edged strategy – combining sterility and biological disruption – enhances the effectiveness of SIT and offers a sustainable, pesticide-free alternative to mosquito control.
Results already on the radar
Experts suggest the strategy could cut tiger mosquito populations by up to 80% in affected areas. Unlike chemical treatments that risk harming ecosystems or breeding resistance, this approach is highly targeted and safe for humans, pets, and the environment.
Spain’s move also mirrors broader global trends in environmentally conscious pest management. Similar initiatives have seen success in countries like Brazil, Singapore and Italy – all facing the challenge of mosquito-borne illness.
Why this matters now
The spread of tiger mosquitoes is accelerating. In Spain, they’re already a permanent fixture along the Mediterranean coast, and their range is expanding due to climate change. Rising temperatures, combined with stagnant water sources in cities and gardens, make perfect conditions for year-round breeding.
Without proactive intervention, the threat is not just itchy bites, but the risk of localised disease outbreaks. Spain’s bold action positions it at the forefront of scientific innovation – choosing precision and sustainability over pesticides and panic.
How to help – and what to avoid
While there’s no guaranteed way to stop tiger mosquitoes completely, a few simple actions can reduce their presence. Natural repellents like citronella, lavender, or eucalyptus oil may help, and wearing light-coloured clothing makes you less of a target. Most importantly, remove standing water from plant pots, buckets, or garden corners — even a bottle cap of water can become a breeding site. Conversely, warm, humid areas with shade and stagnant water are a magnet for these pests, encouraging their spread right into homes and gardens.
Fighting bites with brains
By releasing millions of sterile males into the wild, Spain isn’t making the mosquito problem worse – it’s outsmarting it. In the fight against invasive species and vector-borne diseases, clever science might just be the most powerful weapon of all.
Source: información.es