Although it’s been nearly five years since it arrived in Portugal (in the Algarve and Penafiel), experts have yet to fully decipher the impact of the Asian tiger mosquito (Aedes albopictus), which can spread diseases such as dengue, zika and chikungunya.
“The species was found in Portugal in 2017 for the first time in the Algarve (Loulé) and Penafiel, however, it is not known if it happened at the same time,” José Manuel Grosso-Silva, curator of Entomology at the Museum of Natural History and Science of the University of Porto, told Lusa news agency.
How it reached the Algarve is unknown, but it is believed to have arrived in Penafiel through a tyre retreading dealer. The mosquito eggs were likely in water accumulating inside the tyres, which the expert describes as one of the main ways this species of mosquito spreads.
“The mosquitoes have aquatic eggs, the females lay their eggs in water, and the eggs develop in the water. The tyres, stored in piles, accumulate water inside and provide a place that, on the one hand, has water and bacteria, and therefore food for the mosquito larvae, and on the other has no predators,” said Grosso-Silva.
The specialist adds that there is still “no information of great dissemination of the species from the point” where it was identified in Penafiel. This is neither a “good nor a bad sign”, he says, as “not enough time has passed”.
However, he believes that the species is likely spreading as it has been in Spain because there are no predators – no fish or amphibians – in the areas they were found in the Algarve and Spain.
Said the expert, this is why they spread in the North “much more easily – due to greater availability of water, and even due to climate issues”.
It is also too soon to give a definitive answer regarding the impact these mosquitoes have on ecosystems, although it is “most likely they will cause disturbances to fauna as they don’t feed only on human blood”.
“The females bite different warm-blooded vertebrates, so it is likely they also feed on several species,” he said.
The Asian tiger mosquito arrived in Europe in Albania in 1979 and has since been detected in several European countries, such as Italy, France and Spain.
While it can transmit diseases and parasites, this only happens under some conditions.
“They (mosquitoes) are here, but the diseases they transmit are not here. They need to find an infected person at the right time to bite and become carriers. The parasite must evolve inside the mosquitoes’ bodies, and they must bite the next person in order to transmit it. It’s not a guarantee that a mosquito that bites an infected person will then transmit it,” he explained.