International Ragweed Society

Prof. Victoria Rodinkova, IRS President

Among plants that release allergenic pollen, ragweed has rapidly claimed the lead position in Ukraine in recent years. So rapidly that now virtually everyone knows this word. The plant has spread to all regions of the country, and in the south and east, its flowering period feels like a natural disaster. So why does ragweed cause allergies so actively? And, most importantly, why is this plant so invincible?

To answer these questions, we need to understand what ragweed is and how it distributed all over the World.

Origin and Distribution

The American continent is ragweed’s native habitat. It entered Europe starting in the nineteenth century and especially during World War I, probably by accident through imported seeds and contaminated horse feed, and has spread rapidly since the 1950s. In Europe, common ragweed (Ambrosia artemisiifolia) is primarily widespread, which happens to be the most allergenic among all ragweed species. There are about 30 species in total.

Currently, the species is widespread in southern parts of Eastern and Central Europe, with invasion hotspots in the Pannonian plains of Hungary, Croatia, Slovakia, Romania and Austria. Ragweed is found in Serbia, Italy, Ukraine and Russia. After the 1980s, Ambrosia spread increased rapidly and became a serious threat to human health in the infested countries. Hungary, Northern Italy, and the Rhône Valley in France are considered the most infested European regions, and intense research activities have been dedicated to this topic. The main factors favoring Ambrosia spread are considered to be inappropriate changes in agricultural practices, urbanization, and the international trade of seeds and grains.

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Below is a recording of the latest issue of “Let’s talk about ambrosia” about the presence of Ophraella communa in France.

The IRS Committee is pleased to invite everyone interested in Ambrosia research and management to join our upcoming “Let’s Talk About Ambrosia” online conference! The session will be presented by Zoé Rousset, a PhD researcher at INRAe, who will discuss the spread of Ophraella communa in France since its detection in October 2023. This insect, a natural predator of common ragweed (Ambrosia artemisiifolia), is currently under monitoring to better understand its expansion and potential impact.

The event will feature a 15-minute presentation followed by a 15-minute Q&A session and is scheduled for February 19 at 9:00 AM CET.
For those who are unable to attend, the conference will be recorded and made available afterward.

Join the conference via Microsoft Teams using the following link:

Teams link

Please feel free to share this invitation with your colleagues and networks.
We look forward to your participation!

February 3, 2025 – The International Ragweed Society (IRS) committee met online to discuss recent developments, ongoing projects, and future plans for 2025. The meeting, attended by all Committee members, focused on the outcomes of the
2024 World Aerobiology Conference, upcoming leadership elections, and the latest research on Ambrosia pollen.

Looking Back: 2024 in Review
IRS President, Prof. László Makra, noted that the World Aerobiology Conference 2024 in Vilnius, Lithuania, saw strong participation, although some IRS members were unable to attend. A major highlight was the ragweed-focused scientific session, featuring cutting-edge research on Ambrosia pollen monitoring and transports, meteorological modeling, invasion dynamics and real-time detection technologies, showcasing research from Lithuania, Italy, Turkey, France, and Poland. Among the notable studies presented were:

• Ragweed Pollen and Atmospheric Circulation in Lithuania
• Aerotape: Real-Time Optical Detection of Ragweed Pollen
• Hotspots of Ragweed Pollen in Türkiye and Meteorological Impacts

IRS also provided scholarships to three new members, reinforcing its commitment to supporting emerging researchers in the field. The organization maintains a strong financial position, with membership fees remaining stable for 2025.

Plans for 2025: Strengthening Research and Leadership
With the committee’s mandate officially ending in 2024, current IRS President László Makra has agreed to continue his role through 2026. However, a formal election process will be announced at the next General Assembly, potentially scheduled after the upcoming “Let’s Talk About Ambrosia” lecture.
Also, Tristan Grausi joining the committee to replace Marilou Mottet.
A key priority for IRS in 2025 will be the proposed special journal issue on Ambrosia-related studies, which has received strong support from committee members. The society also plans to expand its online lecture series, with the next talk focusing on Ophraella-Ambrosia interactions, led by the research team of Nicolas Desneux.

Expanding the Scientific Frontier
IRS committee members demonstrated remarkable research productivity in 2024, with 25 scientific publications on ragweed and its pollen. Leading contributors included Yan Sun & Heinz Müller-Schärer (8 papers) and Victoria Rodinkova (6 papers). These publications cover a broad spectrum of topics, from pollen exposure modeling to Bayesian analysis of sensitization patterns.

New Research and Global Collaboration
Discussions also highlighted ongoing and planned ragweed-related research projects. These research projects span global pollen monitoring, machine learning applications, plant-soil evolutionary feedbacks, and human health impacts.

• Yan Sun & Heinz Müller-Schärer are leading multiple projects, including studies on plant-soil interactions and genetic drivers of male/female flower production.
• László Makra is working on machine learning models to predict pollen exposure under future climate scenarios.
• Victoria Rodinkova is spearheading new research on sensitization to Ambrosia pollen in Ukraine.

Additionally, IRS members expressed interest in developing a large-scale European research initiative, possibly under the COST framework.

Enhancing Public Awareness
Recognizing the need for effective science communication, the committee proposed creating informational materials on ragweed invasion and its impacts. These resources, created for both scientists and the general public, could be integrated into press releases and awareness campaigns, including Ragweed Day initiatives.

Looking Ahead
The next IRS committee meeting is expected in April or May 2025, providing an opportunity to finalize research plans and solidify organizational goals for the year ahead. As IRS continues its mission, 2025 promises to be a year of scientific collaboration, strategic expansion, and impactful outreach in the fight against ragweed-related health challenges. The IRS continues to play a crucial role in coordinating international research efforts on ragweed, a plant species of significant environmental and public health concern.