The study aimed at analyzing Magnaporthe oryzae population structure in Benin Republic, using Near Isogenic Lines and differential rice varieties in order to characterize the virulence spectrum of blast populations, as well as identifying the best blast disease hotspot screening sites. Blast trapping nurseries using 30 Near Isogenic Lines and 2 other rice varieties were setup in 4 blast disease hotspots (Kokey, Kandi, Ouedeme and Bagou) in Benin. The experiment was setup in a Fisher block design with three replicates. Blast disease was evaluated weekly from 21 days after sowing. The blast pathogen pressure was generally higher in hotspots/sites in the Northern part of Benin. The races of M. oryzae in 3 sites (Kokey, Kandi and Bagou) were able to overcome 9 resistance genes (Pi1, Pi7, Pi5, Pikp, Pia, Pita2, Piks,Pi3 and Pik). However, in Ouedeme, the M. oryzae races were able to overcome 13 resistance genes (Pi1,Pi7, Pi5, Pikp, Pia, Pita2, Piks, Pi3, Pik, Pita, Piz, Pikh and Pikm). Ouedeme site was therefore identified as the best site for use to screen for durable resistance to blast disease in Benin Republic. This information is useful for development of durable resistant variety to blast disease in Benin.

Key words: Magnaporthe oryzae, pathogenicity, disease hotspots, resistance genes, durable resistance.