The spread in Europe of the North American ragweed weed has resulted in an estimated 13.5 million cases of allergies. Such conclusions were reached by scientists, whose research was published in the scientific journal Nature Communications.
“Our research shows that we significantly underestimate the damage that ragweed causes to human health and the economy of Europe. On the other hand, these same observations indicate that this problem can be addressed with the help of leaf beetles of the species Ophraella communa, which eat this plant "- said one of the authors of the study, an ecologist from the intergovernmental organization CABI (The Center for Agriculture and Bioscience International) Urs Schaffner.
The so-called invasive species became one of the main problems for the ecological situation of the Earth a few decades ago. This is how biologists call animals that have found themselves in new territories thanks to the "help" of man.
In particular, the penetration of Brazilian fire ants into the United States in the middle of the last century led to the fact that several species of snails disappeared from the face of the Earth, and the number of other species of invertebrates and even mammals decreased significantly. In turn, the African fungus of the Batrachochytrium dendrobatidis species, which penetrated Europe, America and Asia, has destroyed 90 species and millions of amphibians over the past two decades.
A striking example of invasive plant species, as noted by Schaffner and his colleagues, is the so-called wormwood ragweed (Ambrosia artemisiifolia), a herb from the Aster family. Her homeland is in North America. Over the past two decades, ambrosia has spread throughout the states of the former USSR, including Russia and Ukraine, in the countries of South Asia, as well as in three dozen countries in Europe.
Plant roots of allergies
According to American doctors, this plant is the cause of approximately 25% of allergy cases in the United States. In this regard, its appearance in the countries of the Old World caused great concern among doctors. Unlike the USA and Canada, where ragweed is constantly attacked by beetles of the species Ophraella communa and many other insects, in Europe this plant has no natural enemies. Due to this, ragweed produces significantly more pollen and blooms more often.
Seven years ago, Ophraella communa beetles were accidentally brought to Italy and a number of other southern European countries, where they took root and began to eat ragweed. Environmentalists tried to assess the positive and negative consequences of this event, as well as to understand how much the spread of this plant affected the frequency of allergies.
To do this, they studied how the amount of Ambrosia artemisiifolia pollen has changed in different regions over the past seven years, depending on whether leaf beetles live there. Scientists have compared this data with the number of diagnosed cases of allergies. It turned out that the level of danger of ambrosia for the health of Europeans was greatly underestimated.
In particular, in 2013, more than 13.5 million Europeans suffered from the allergy caused by Ambrosia artemisiifolia pollen. The economic damage from the spread of ragweed, according to estimates by Schaffner and his colleagues, was approximately € 7.4 billion, which is about eight times more than previous estimates. The southern regions of France and northern Italy, as well as Bulgaria and a number of other countries in southeastern Europe, were particularly affected by this.
On the other hand, as subsequent observations and experiments of ecologists have shown, the spread of beetles in some regions of Europe has significantly improved the situation in them. Within three years after their appearance, the amount of ragweed pollen particles in the air decreased by about 82%, and in some parts of Italy it completely disappeared.
According to Schaffner and his team, this suggests that Ophraella communa can be used to control the further spread of ragweed. Their widespread distribution, as shown by scientists' calculations, can reduce the number of allergy cases by 16% (2.3 million cases). This will significantly reduce the burden on the health care system in the EU and other countries in the region.