Abstract
This study evaluates the threat to French agriculture of Meloidogyne graminicola, a rice root-knot nematode recently found in Lombardy, Italy. With a significant crop damage potential, M. graminicola raises concerns about its spread into France's key farming regions, especially the only rice-growing region in mainland France, the Camargue, and where rice and wheat rotations are common. Controlled bioassays compared the aggressiveness of four M. graminicola isolates from Italy, Vietnam, Cambodia and Borneo. These isolates were tested on selected rice cultivars and wheat species to evaluate infection potential. Results showed that the Italian isolate was less aggressive than the Asian isolates—particularly those from Cambodia and Borneo—with lower reproduction index and fewer galls on rice. Still, the Italian isolate successfully infected all the tested rice cultivars and both soft and durum wheat, which could enable its spread across France from the Camargue region. This study is the first to compare the aggressiveness of the Italian M. graminicola isolate with other aggressive isolates from other regions, providing crucial insights into the nematode's potential to spread to new European environments. The results highlight the need for surveillance, improved biosecurity and application of alternative nematode management strategies, such as diverse crop rotations or using resistant rice cultivars to counter this threat.