A beetle appears to have the greatest potential in the biological protection against ragweed, scientific evidence has shown. The ragweed leaf beetle has already appeared in Hungary, but only in small quantities. The Plant Protection Institute of the ELKH Centre for Agricultural Research (ATK NÖVI) has signed an agreement with the National Food Chain Safety Office (NÉBIH) to survey the occurrence of the insect in Hungary and to plan further studies to learn about its behaviour domestically. The experts at ATK NÖVI are using the citizen science method, i.e. involving the general public – amateur entomologists, farmers and hikers – to investigate where and in what quantities the ragweed leaf beetle is present in Hungary.
The most important allergenic plant in the country is ragweed, and its control is a social issue. It is therefore important that researchers develop biological control methods that can reduce pollen production. This is where the ragweed leaf beetle (Ophraella communa), which is not native to our country, can help. "It originates from North America, where the host plant comes from," explains Jenő Kontschán, Director of the ATK NÖVI.
The beetle has already appeared in Italy, Croatia and Serbia, and last year some part-time entomologists found it in the Soroksár area of Budapest. According to Jenő Kontschán, its appearance was to be expected, as its occurrence in Croatia and Serbia is 100 kilometres from the Hungarian border, and it is common for animals to appear in new habitats through natural dispersal.
The ragweed leaf beetle – primarily its larvae – chews on ragweed, causing easily recognizable damage to the leaves of the plant. Studies in Italy have shown that where there is a stable population, the pollen production of ragweed decreases by about 30 percent.
"However, it is not as simple as that," added Jenő Kontschán, "as the only known occurrence of the beetle in Hungary is in Soroksár, which is relatively far from the other distribution areas." It is not possible to say whether this is the result of a one-off introduction or whether the species may already be more widespread in the country.
The researchers at ATK NÖVI are therefore asking for the help of the general public – entomologists, farmers and hikers – to assess the spread of the ragweed leaf beetle in Hungary last fall and to better define its occurrence.
The beetle is easily recognizable. It is around half a centimetre long, yellowish-brown in colour, and with black longitudinal bands on its wing case. It is primarily found on ragweed and can be observed with the naked eye.
Experts are asking anyone who recognizes the beetle to send details of its exact occurrence, the date and location of its sighting, and, if possible, a good-quality photograph to email@example.com.
The researchers are also interested in how the insect can occur on food crops other than ragweed. Another interesting question is whether, if it survives in Hungary, it can reduce the amount of ragweed pollen with the same effectiveness as in international examples. Jenő Kontschán added that if the beetle colonizes the country, it will cause some level of pollen reduction, but it will not solve all problems, so the calls to cut back ragweed should continue to be fully respected – whether the beetle is with us or not.