This Bug Could Help Protect Millions Of People From Hay Fever


Tom Hale

Senior Journalist

clockApr 21 2020, 17:22 UTC

Ophraella communa on flower in Alessandria, Italy. Hectonichus/Wikimedia Commons CC BY-SA 4.0

If your love of the great outdoors is often blighted by itchy eyes and a runny nose, you might be interested to meet a hungry little bug known as the leaf beetle. Though smaller than an apple seed, new research has shown that introducing these beetles into the wild could be the key to easing hay fever symptoms for millions of people.

Hay fever is caused by your immune system’s overzealous reaction to the pollen of plants. Different people can experience allergic reactions to different types of pollen, including grass pollens (often between May and July), tree pollen (February to June), and weed pollen (June to September). 


Of pollens great and small, however, one of the worst offenders stems from a pesky plant known as the common ragweed (Ambrosia artemisiifolia), accounting for the main source of hay fever for at least 13.5 million people in Europe alone. Originally native to the Americas, the plant has recently colonized up to 30 countries across the world and its spread is only set to increase with rising temperatures caused by climate change. But a new study has offered a solution to ease this pollen-heavy weed.

Reporting in the journal Nature Communications, scientists propose the idea introducing the leaf beetle (Ophraella communa) into more parts of the wild can significantly reduce pollen by eating the common ragweed and acting as a biological control.

Common ragweed (Ambrosia artemisiifolia). CABI

To assess how much the leaf beetle can reduce pollen, the researchers modeled the seasonal total of ragweed pollen in Europe during 2004 and 2012, prior to the introduction of the leaf beetle, and paired it with detailed healthcare data from a region in southeastern France. This gave them a clear idea of how sensitive people in the European population are to ragweed pollen – and how many could benefit from the loss of the plant. They then looked at this data alongside information about how populations of the leaf beetle can affect the levels of this pollen across their range. 

Simply by introducing the leaf beetle to new parts of Europe, the researchers project over 2 million people could be relieved from their hayfever symptoms, in turn saving over €6.4 billion (around $6.9 billion) in healthcare costs each year.


"Our study provides evidence that the impacts of common ragweed on human health and the economy are so far highly underestimated, but that biological control by Ophraella communa might mitigate these impacts in parts of Europe,” Dr Urs Schaffner, lead author of the study from Centre for Agriculture and Bioscience International, said in a statement.

But is it naive to flood the ecosystem with a new bug to take out another invasive species? What if this beetle suddenly gained an appetite for other species of plants, or even agricultural crops? While this is always a risk, the researchers say this shouldn't be a problem with the leaf beetle. 

"We were not sure at first whether the leaf beetle was useful or harmful. Laboratory tests had shown that it was possible that it was harmful to sunflowers. However, field tests in China and Europe could not confirm this finding," said Professor Heinz Müller-Schärer, study author from the University of Fribourg.

  • tag
  • plant,

  • hay fever,

  • allergy,

  • invasive species,

  • biological control,

  • leaf beatle,

  • common ragweed