The tiger mosquito has already established itself in almost 800 Catalan municipalities.

BarcelonaIn the summer of 2004, two decades ago, one of the major media stories was the presence of a mosquito with black stripes that was larger than the native mosquito and caused more painful bites. Originating from Southeast Asia, Sant Cugat del Vallès was the first place in Catalonia where it was detected, almost twenty years after it entered Europe camouflaged in trucks transporting tires. Little by little, the insect has now become a integrate into everyday life every time the thermometer gets hot, to the point that it feels like the tiger mosquito (Aedes albopictus) has become the lord and master of the entire country. A study published this Thursday by a Catalan team in the journal Insects, The study, which includes the first map of invasive mosquitoes, indicates that this species has colonized some 780 of the 947 existing Catalan municipalities. The study is based on the analysis of data collected by both technicians and citizens who have reported the presence of the mosquito through the application. Mosquito Alert, a citizen science project that brings together around forty scientific entities, including the CSIC, the UPF, and the Blanes Center for Advanced Studies (CEAB).

From Sant Cugat, the tiger mosquito spread rapidly throughout the Barcelona metropolitan area and is now found practically throughout Catalonia, especially in coastal and pre-coastal municipalities: from the Ebro to the northern Costa Brava. It therefore affects large urban concentrations, that is, where the bulk of the population lives. At the national level, two-thirds of the inhabitants live in an area colonized by the insect.

According to the study data, the latest towns where the insect's presence has been detected are, for example, Almacelles, Alòs de Balaguer, Lles de Cerdanya, Les Llosses, Puigcerdà, and Ripoll. The list is shorter when you want to know whereAedes albopictus It hasn't been seen. These are towns like Lladorre, Ivars de Noguera, Maldà, and Oliola, to name a few. In the Valencian Community and the Balearic Islands, the situation is even more worrying than in Catalonia, because the mosquito has taken hold across the entire island and now controls almost all of Valencian.

The research, led by entomologist Roger Eritja of CEAB-CSIC and Frederic Bartumeus of Mosquito Alert, did not limit itself to analyzing the behavior of the tiger mosquito, but also extended the radar to other invasive species that have already been detected in Spain. This includes, for example, the so-called Japanese mosquito (Aedes japonicus), first found in 2018 and concentrated in the northern Atlantic regions, attracted by milder temperatures; andAedes aegypti, which is capable of transmitting yellow fever or dengue fever and is limited to the Canary Islands, although it should be remembered that it was present in the Mediterranean until the middle of the last century. In total, these mosquitoes are known to be present in 22% of the Spanish municipalities.

Eritja explains that the spread of these insects depends on "basically human factors," such as trade and freight transport routes, and a suitable climate. In this regard, she indicates that colonization of the Mediterranean coast has been "relatively rapid," but that it is slowing down inland. However, this trend does not mean the battle has been won: in Italy, where the tiger mosquito was detected in 1990, "it is currently established throughout the entire territory," the expert points out.

Citizen contribution

The municipal map was obtained thanks to the collaboration of scientists conducting field sampling and more than 100,000 detections by 33,000 citizens who reported them through Mosquito Alert. The combination balances the strengths and weaknesses of both methods: "Field entomologists provide incontrovertible physical evidence, but it is slow to obtain, very local, and entails high costs," explains Eritje, who emphasizes that "citizens, with their mobile phones, can detect mosquitoes anywhere and can transmit photographs."

This immediacy can alert authorities and facilitate rapid intervention. While invasive mosquitoes cannot be permanently eradicated, if they are detected when they have just arrived in an area "they can be eliminated locally." But Eritje warns that exterminating them is not easy: they will surely reappear.because globally they do not regress".