Quirks & Quarks

Ragweed allergy sufferers in Europe get relief thanks to invasive beetle

Invasive ragweed in Europe has been a plague but a recently arrived beetle that devours it is reducing misery for allergy sufferers

An old invader is being attacked by a new invader

Invasive leaf beetle destroys ragweed before the plant can produce pollen. (Heinz Muller-Scharer)

Invasive insects often do harm, but a leaf beetle that arrived recently from North America is providing relief for allergy sufferers in Europe — and saving millions of euros in health-care costs. 

The leaf beetle Ophraella communa attacks ragweed and significantly reduces the amount of allergy-inducing pollen released by these plants, according to biologist Urs Schaffner. He led a team that has published a study in the journal Nature Communications describing the phenomenon.

Ragweed pollen causes sneezing, itchy eyes, runny noses, and can aggravate conditions such as eczema and asthma. 

Prior to the accidental arrival of the leaf beetle in 2013, about 13.5 million Europeans suffered from ragweed-induced allergies, resulting in health-care costs of approximately 7.4 billion euros annually, according to researchers. (CABI)

Ragweed itself is an invasive species in Europe, originating in North America. In the last several decades, it has spread widely through the continent, moving northwards as the climate has warmed.  This has led to a huge increase in misery for allergy sufferers.

An estimated 13.5 million people suffered from ragweed-induced allergies in Europe up until  2012. This costs health-care systems billions of euros.   

However, after 2013 — when the beetle was first detected near Milan's international airport — researchers noticed a sudden decrease in the number of people suffering allergic reactions to ragweed pollen, particularly in Italy. 

Leaf beetle and larvae defoliate ragweed. (Heinz Muller-Scharer)

Schaffner, the head of ecosystems management at the Centre for Agriculture and Bioscience International in Switzerland, has participated in intentional introductions of insects to control pest plants. In this case the introduction of the leaf beetle seems to have been accidental. 

Accidental or not, it's been enormously successful. In the Milan area, most ragweed plants have been killed by the invasive leaf beetle before they were able to release pollen.

In other areas where the beetle has been detected, ragweed pollen has been reduced by up to 82 per cent. That represents an estimated reduction in the number of ragweed sufferers by about two million. 

There is no evidence at this point to suggest the beetle is a risk to crops and other plants.

 

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