Genetic hybridization between C and R strains of Spodoptera frugiperda (Lepidoptera, Noctuidae) in Burkina Faso

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is a devastating pest that causes significant crop losses and threatens food security throughout sub-Saharan Africa. In Burkina Faso, FAW is present since 2017, but its diversity is poorly understood, which complicates control efforts. Morphological identification of the larvae collected in the field was followed by molecular characterization using the genetic markers cytochrome oxidase I (COI) and nuclear triose phosphate isomerase (Tpi). The larvae were collected from maize and sorghum fields in two of the country's agroecological zones. The analyses confirmed the coexistence of the two strains but identified a critical divergence. While the mitochondrial COI marker identified distinct maternal lineages corn strain (C) and rice strain (R), the nuclear Tpi gene revealed a high prevalence of heterozygotes. This provides evidence of frequent hybridization between populations in the field. Additionally, genetic analysis of populations based on both markers revealed high haplotype diversity and no evidence of significant genetic structure between agroecological zones. This indicates a panmictic population with high gene flow. These findings provide the first evidence of FAW CxR hybrids in Burkina Faso. This emphasises the significance of genetic diversity in the pest's capacity to adapt and underscores the necessity of management strategies that consider population genetics.