Mosquitoes that transmit diseases such as malaria, dengue or Zika virus have found a paradise in cities. Although their original habitat for laying eggs is the hollows of trees in rainforests, where there is stagnant water, these insects have adapted very well to urban environments.
For them, a pot represents an ideal nest. Two researchers, one from Miami and one from Pisa, have analyzed what makes these animals so habituated to cities in southern Europe and the United States.
Apparently, it is the perfect environment! There are hardly any predators that threaten their life. They have thousands of humans to suck blood and hundreds of places with flooded water, the perfect habitat for females to lay eggs.
There are not enough salamanders, lizards or bats in the cities to stop the conquest of mosquitoes. Think of how many possible predators they have to face in the Amazon compared to any big city.
Research specifically analyzes the expansion of two of the main species responsible for transmitting diseases: Culex coronator and Aedes albopictus. The latter is the tiger mosquito, which is part of the fauna in many forests.
This species breeds attached to the houses. An ashtray in a garden that has run out of the water three or four days after watering is enough for the larvae to grow.
In many cities in Europe, tiger mosquitoes arrived to stay, because of people’s bad practices when it comes to keeping containers with enough water that mosquitoes can use to breed and propagate.
Despite multiple warnings about the danger of leaving standing water several days in any container, the truth is that in practice it is very difficult to control. A maximum emergency situation would be necessary for authorities to enter private properties in search of possible nests.
Experts recall a 2016 plan for preparing and responding to vector-borne diseases, a document that is currently being updated.
The transfer of tourists from endemic countries adds to the fact that mosquitoes adapt to new environments. This has already caused dengue cases where they had never been seen before. These cases are small notices of what may come.
When an infestation has already taken place, it is practically impossible to eliminate the mosquito from an environment. That is why it is necessary to emphasize prevention and the authorities have to develop guides so that citizens understand the problem.
If your neighbor does not follow the rules, there is nothing to do. In Miami, there is a big problem with bromeliads –beautiful flowers that naturally store water. That water houses hundreds of larvae.
According to analyses, the tiger mosquito has already successfully invaded nine European countries. The first in which its presence was detected was Albania in 1979, then Italy in 1990, France in 1999, Greece and Switzerland in 2003 and Belgium and Spain in 2004.
The last places where specimens of this species were collected were Germany and the United Kingdom just four years ago.
In the United States, the presence of Tiger mosquitoes has been extended to 36 states since its existence was confirmed in 1985 in Texas. This rapid expansion confirms the great flexibility of adaptation of the specimens.
The Coronator species has been successfully installed in six states in the southeastern United States. Its presence was first detected in Louisiana in 2004. Only in one region of Miami, scientists collected more than 27,000 females of this species in urban areas in just over two years.
One of the main conclusions of this research is actually a warning: it is necessary to study in more depth the mechanisms that these mosquitoes use to adapt so well to urban life. Only then can this threat be addressed.
Scientists warn that there could be other potentially dangerous invasive species of which there is no record.
The recommendation made by experts is that the population of these vectors be kept under strict supervision to avoid a public health problem.
These mosquitoes can lay around 500 eggs in their entire lives. Nature is responsible for killing most. But in a city where there are no predators, almost all of them can survive.
In this scenario, the natural balance disappears, and the mosquito population can grow out of control if there are no specific plans.
With its ubiquity and the great human mobility that currently exists we will see more outbreaks of diseases that we did not expect worldwide.
The traditional vision has been to kill mosquitoes, but we have already seen that this is very difficult to do because of the rapid way in which they spread.
Estimates indicate that almost half of the world’s population is at risk of having an insect-borne disease.