Spread of Striga asiatica through suitable climatic conditions: Risk assessment in new areas producing Zea mays in South America

Striga asiatica (dicot), an obligate hemiparasitic of monocots, is a potential threat to South America. Determining the ecological factors that explain the occurrence and predicting suitable areas for S. asiatica are fundamental for designing prevention strategies. We developed a Spatio-temporal dynamics model and evaluated Brazil's Weekly Growth Index (GIW) for S. asiatica. We analyzed four Brazilian regions (Central-West, South, Southeast, and Northeast) to verify the local seasonal variation of the species in climatic data. Our results indicated areas with favorable climatic suitability for the species in part of South America. Seasonal assessment models showed that high rainfall and the dry and cold periods common in tropical regions affect the GIW for S. asiatica. When we associate periods with maximum rainfall of 53 mm per week and temperature above 20 degrees C, the GIW approaches the optimal index for the regions evaluated, indicating the influence of soil moisture and air temperature. Our risk assessment indicated that the Southeast and Northeast are at the most significant risk of S. asiatica invasion. Projections for climate change between 2040-2059 showed expansions in areas suitable for S. asiatica compared to the current climate of South America.