Hordes of buzzing but sterile mosquitoes are being let loose in Zagreb as Croatia attempts to prevent possible climate change-related diseases.
The release is part of a project focused on eradicating invasive Asian Tiger mosquitoes known for spreading sicknesses like Dengue Fever, Chikungunya and Zika.
The species has appeared to thrive in the country and across the region in recent years partly due to climate change, with the warmer weather providing fertile ground for the mosquito.
Zagreb resident Kruno Lokotar has mixed feelings about the project and says: "It's too early to say whether this one will yield results, but I'm glad that we are not just sticking with spraying."
Sterilising males
Croatia's plan is to neutralise further breeding of the mosquitoes by releasing sterilised males into the wild to mate with females.
"If we release a sufficient number of sterile males during a certain period in an area, the mosquito population in that area will decrease," Ana Klobucar, a medical entomologist of the Zagreb-based teaching institute of public health who is overseeing the project, told the AFP news agency.
The Zagreb project kickstarted in June, when 100,000 mosquitoes were released in a high-risk area with thick foliage where mosquitoes often congregate.
The country plans to release a total of 1.2 million specially treated insects over a three-month period, entomologist Nediljko Landeka of the regional public health institute said.
The plan is rooted in the Sterile Insect Technique (SIT), which has been used for decades across the world to combat various harmful insects. The method is however still being tested for its effectiveness against mosquitoes in urban areas.
Croatia started using it for mosquitoes last year in northern Istria peninsula.
During the Istria trial, up to 14% of mosquito eggs in the area were found to be sterile and jumped to nearly 60% this year, Landeka added.
Climate change impact
The insects, which have been rendered sterile after exposure to gamma rays, are sourced from a laboratory in Italy, and shipped 500 kilometres to Croatia in special boxes.
Once received, Klobucar and her assistants carefully remove plastic bowls with the insects from cardboard tubes before they are later dispersed in local gardens in the target area.
Croatia's programme coincides with increasingly dire warning from experts that global warming could make swaths of Europe more vulnerable to infectious diseases spread by mosquito bites.
The presence of the Asian Tiger mosquito in Croatia was first recorded in 2004 after arriving in Europe in the late 1970s, with experts suggesting they made the journey in used tyres that arrived in Albania from China.
Official figures indicate that the breed has now spread to more than a dozen European countries, with the Mediterranean region having been hit the hardest.
As the mercury rises across the globe, the Asian Tiger mosquito is moving further north including in areas that were considered too cold for the species to thrive, including in Switzerland and Germany.
"We are afraid that together with the species, viruses could also easily adapt in the future to new environments," Greek entomologist Antonios Michaelakis warned.
Michaelakis, a researcher at the Benaki Phytopathological Institute in Athens, has also been instrumental in sharing his experiences from a programme in Greece with his Croatian counterparts.
In Greece the project succeeded in slashing the population of Asian Tiger mosquitoes by 90 percent in 2019, he said.
