Genetic Diversity of the Fall Armyworm Spodoptera frugiperda (J.E. Smith) in the Democratic Republic of the Congo

In 2016, the fall armyworm (FAW), Spodoptera frugiperda, invaded western Africa and rapidly spread in sub-Saharan Africa, causing significant losses in yields of corn, a major food crop in Africa. Although the Democratic Republic of the Congo (DRC) is a large corn-growing country, the impact of FAW has not been investigated. This study was designed to expand investigations on the genetic diversity of FAW populations in the DRC. We collected FAW individuals from eight provinces across the country, for analysis of genetic variation. Based on the partial sequences of both mitochondrial cytochrome oxidase subunit I (COI) and nuclear triosephosphate isomerase (Tpi) genes, we compared polymorphic features of the COI haplotype and Tpi single nucleotide polymorphisms. The results revealed that most (84%) of the analyzed individuals were heterogeneous hybrids Tpi-corn/COI-rice (Tpi-C/COI-R), whereas 16% were homogenous Tpi-corn/COI-corn (Tpi-C/COI-C). Further analysis of the fourth exon/intron sequences of the Tpi gene identified two subgroups, TpiCa1 and TpiCa2, constituting 80% and 20%, respectively, of the collected individuals. Analysis of genetic variation among native and invasive populations indicated significant genetic differences (10.94%) between the native American and DRC populations, whereas both the DRC and African populations were genetically closer to Asian than American populations. This study provides important information on FAW genetic diversity in the DRC, which can be used for effective management of FAW.