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Beetle can limit hay fever

Leiden biologist Suzanne Lommen and an international team of scientists have investigated how a beetle can reduce hay fever in Europe. Locally, the beetle is even able to stop pollen production in a plant that causes allergic reactions. Publication in Nature Communications on April 21.

Common ragweed (Ambrosia artemisiifolia)

Invasive alien species

Itchy eyes, sneezing and shortness of breath: these are some of the symptoms of hay fever that affect millions of people in Europe. A plant that can evoke an allergic reaction and which is emerging in Europe is common ragweed (Ambrosia artemisiifolia). The invasive alien plant species from North America is now found in more than thirty European countries. An international team of researchers quantified the effects of A. artemisiifolia pollen on public health in Europe and investigated the extent to which the beetle Ophraella communa, a natural enemy of the plant, could reduce pollen production. Researcher Suzanne Lommen of the Institute of Biology Leiden contributed to the study.

Billions of healthcare costs

To find out the plant's effects on public health, the researchers combined data from European pollen monitoring stations with human population density, the sensitization rate among the human population for common ragweed, and the average cost of the medication and absence from work. They used data from 2004 to 2012, because at the time the beetle O. communa was not yet found in Europe. The results estimate the effects of the plant on public health without beetle intervention: 13.5 million Europeans who suffer from the pollen, and 7.4 billion euros for healthcare costs and work absence annually.

Suzanne Lommen in a field with common ragweed

Devastating effect

The researchers then looked at the impact that the beetle O. communa has on the pollen production of common ragweed. The beetle has a devastating effect on the plant. In the field, the beetle almost exclusively eats only common ragweed, and as a result, affected plants produce less pollen or none at all. With field studies in Italy, Lommen investigated the impact on pollen production when the beetle attacks the plants. She concluded that the beetle can reduce pollen production by an average of 82%, and sometimes even stop pollen production altogether. The research team has projected that further dispersal of the beetle across Europe could lead to a decrease of approximately 2.3 million hay fever patients in Europe. This would save 1.1 billion euros annually.


The beetle has not spread all across Europe, and cannot be introduced overnight, according to Lommen. ‘Common ragweed is already a problem in France, but the beetle is not yet there. The French are eager to introduce the beetle, but that is not allowed because it is an alien species. Now that the effect of the beetle has been thoroughly investigated, the French government has concluded that it is safe to bring the beetle to France. However, that is not so simple because of their legislation. Let’s hope the beetle will soon cross the Alps by itself!'

Header image: Ophraella communa. Image by Judy Gallagher (CC BY 2.0)

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