The tiger is awakening. Not the feline, but the mosquito. It has already been reported in Southern Italy and experts expect to soon spot it further North, in Milan. In the spotlight since the Dengue alert was triggered, in the wake of the emergency situation they are experiencing in South America, Aedes albopicuts, the real scientific name of the tiger mosquito, is entering its season. And this is why “it is a priority to promptly reduce the number of mosquitoes that can be potential vectors of viruses in general”. Sara Epis, associate professor of parasitology at the University of Milan, paints a picture of the situation today. Mission: to 'map' the buzzing insect with the team of colleagues from the Entopar group, for a complete census of this invisible population that inhabits the Peninsula.
In the Lombard capital, he explains to Adnkronos Salute, “at the moment the tiger mosquito has not yet been reported. It is not present because the nights are still quite cold. Unlike in the South. Already, for example, in Rome this species is circulating, so much so that the Capital has started with the disinfestation and control campaigns in the city. Obviously it always depends a lot on the climatic conditions, but we expect that by the end of the month the tiger mosquitoes will begin to circulate in us too. And in fact at the end of April we will begin the our monitoring activity, which we had already started in the context of the Musa Project” – Multilayered Urban Sustainable Action, a maxi project financed with Pnrr funds which involves various universities and studies in multiple dimensions how to transform the metropolitan area of Milan to improve the well-being of people and sustainability.
The one who is already making itself felt is the Culex pipiens mosquito, our nocturnal mosquito, an important vector of the West Nile virus. “It is already circulating, we have already found some in the city of Milan, some adults present”, reports Epis. As for the tiger mosquito, feared more than ever in Italy this year, “it is a widespread species in the urban area – says the expert – This is a mosquito that adapts very well to different conditions and domestic environments, just a little is enough water so that it can lay its eggs. Therefore, saucers, buckets left on balconies or in gardens, or all those areas that have stagnant water in city parks are favorable environments for development. It is a mosquito that therefore does not requires particular situations” to 'thrive'.
Are some Milanese neighborhoods generally a favorite home for the tiger mosquito, and therefore more infested than others? “We are working in different sites and its distribution is rather homogeneous throughout the territory – observes the expert – Obviously last year during the summer in the areas where important disinfestation campaigns are carried out we captured a limited number. While instead we worked in particular in areas such as the botanical gardens, where they were reported, therefore in the center of the city anyway”. In short, any zip code in the metropolis can be suitable for them. The methods that are generally used to control mosquito populations and on which there is a lot of focus at the moment “are the use of insecticides and the use of larvicides, in particular those based on Bacillus thuringiensis, an eco-friendly and effective system that it can also be used at a domestic level to kill the larvae in a selective manner. This is what the national plan for prevention, surveillance and response to arboviruses provides.”
So far, the Epis analysis continues, “fortunately we have no reports of the Aedes aegypti mosquito, which is the true vector of Dengue and Zika. However – he points out – this is still present in some countries bordering the Mediterranean area It is permanently present in Portugal on the island of Madeira, in the Black Sea, in Cyprus”, he lists. “And for this reason it is particularly 'attentive'. Luckily it is a mosquito that does not survive the winters, that is, it does not resist low temperatures. So at least in all of Northern Italy it is difficult for it to stabilize.” Unless, as several experts warn, climate change wreaks havoc on the Italian weather in the future. Returning to the present of the fight against mosquitoes already 'at home', “the absolute priority is to guarantee complete protection of the areas, limiting development outbreaks through prevention interventions and treatments with larvicides. And – Epis reiterates – to invite citizens to contribute to these control strategies, because the Municipality can do its part, but if private gardens, balconies and vegetable gardens have stagnant water, it becomes very difficult to try to limit the number of these insects. “It is really essential to reduce the quantity of mosquitoes which can then be potential vectors of viruses in general.”
The news events speak clearly. “The alarm has already been raised almost everywhere, especially in relation to what is happening in South America, where the healthcare system is really under pressure”, confirms Epis. Dengue “will not have the same impact here – he reassures – because we do not have so many infected people and so many mosquitoes as in tropical areas, but attention is needed”. “Already, in my opinion – he comments – we are trying to do more than what was done in the past. We have specific interventions planned by the Ministry of Health, by the experimental zooprophylactic institutes. But it is never enough. The cases are there. And it is important that researchers and universities also contribute. And that citizens lend a hand.”
CLIMATE CHANGE EFFECT – Meanwhile, mosquitoes are changing 'home'. And climate change is also partly to blame. The issue of climate change is also called into question by many experts to delve deeper into the trend that is bringing diseases once defined as tropical to many other latitudes. “Climate change – explains Epis – impacts the physiology, behaviour, life cycle and therefore also on the geographical distribution of the different mosquito species. And this is certainly one of the factors that is greatly influencing the spread of native and alien species such as Aedes japonicus or Aedes koreicus”, i.e. the Japanese and Korean mosquitoes, “which have adapted very well to our climates”.
THE RARE SPECIES OF MILAN – In the shadow of the Madonnina a 'babel' of languages and buzzes. Milan, a cosmopolitan metropolis, could not fail to have its 'melting pot' of mosquitoes. Which species have chosen the Lombard capital as their home? “We have already started our activities again to try to understand if we reconfirm the 'recorded' species. Among those that we have identified in the urban areas of the city, the tiger mosquito obviously dominates” and there is also “Culex pipiens”, the common mosquito, very active at night and already 'at work'. But “talking about biodiversity in the city of Milan, the interesting thing is that last year, doing our monitoring work (which we will resume shortly), we saw that there are also quite rare species in our metropolis, which could still be considered competent vectors of viruses for humans”.
Epis draws the 'map' of city mosquitoes. The expert with the team of colleagues from the Entopar group (Agata Negri and Irene Arnoldi in particular), as part of the Pnrr Musa project, works on a complete census of the population of stinging insects. Activities that you have reserved some surprises, such as the sighting of rare species, on which a scientific publication is being prepared. “These are species that have certainly never been reported in Milan”, mentions the expert. Where do they come from? “They are already present in our territory – she specifies – but they are rare species that we did not expect to find in an urban environment such as that of a metropolis”. Practically mosquitoes on the move. “Obviously they need to be monitored, they are already stable populations but they occupy particular environments and therefore they are not expected to expand much”, says Epis.
While we await the awakening of Aedes albopictus (tiger mosquito) even in the coldest cities of the North, Culex is already circulating. “However, at the moment, those more resistant invasive species such as the Korean mosquito and the Japanese mosquito (Aedes koreicus and Aedes japonicus), which are the ones on which we pay particular attention, are not present in the city of Milan. Both are present in other cities of the Lombardy, particularly in Northern Italy. They survive very well in the coldest climatic conditions, and we have been observing and collecting them since March – reports Epis – They are more rural mosquitoes and to date they have not yet been found in the Milanese metropolis.
In terms of population size, giving a quantity of mosquitoes in Milan “is obviously difficult – smiles the researcher – The feeling is that there are numerically fewer of them than in the cities of the South, or in a city like Rome, but it is difficult to say. Compared to In the past there are certainly more, especially because we have these invasive alien species that have now become native, such as the tiger mosquito, which was not present until twenty years ago.”
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