Comparative molecular analyses of invasive fall armyworm in Togo reveal strong similarities to populations from the eastern United States and the Greater Antilles

Abstract

The fall armyworm (Spodoptera frugiperda, J.E. Smith) is a noctuid moth that is a major and ubiquitous agricultural pest in the Western Hemisphere. Infestations have recently been identified in several locations in Africa, indicating its establishment in the Eastern Hemisphere where it poses an immediate and significant economic threat. Genetic methods were used to characterize noctuid specimens infesting multiple cornfields in the African nation of Togo that were tentatively identified as fall armyworm by morphological criteria. Species identification was confirmed by DNA barcoding and the specimens were found to be primarily of the subgroup that preferentially infests corn and sorghum in the Western Hemisphere. The mitochondrial haplotype configuration was most similar to that found in the Caribbean region and the eastern coast of the United States, identifying these populations as the likely originating source of the Togo infestations. A genetic marker linked with resistance to the Cry1Fa toxin from Bacillus thuringiensis (Bt) expressed in transgenic corn and common in Puerto Rico fall armyworm populations was not found in the Togo collections. These observations demonstrate the usefulness of genetic surveys to characterize fall armyworm populations from Africa.

Comparison of pheromone trap design and lures for Spodoptera frugiperda in Togo and genetic characterization of moths caught

“…In comparison, the diagnostic rice strain Tpi marker, TpiR, was rarely found in all collections (frequency <0.06), consistent with earlier findings based on a survey of larval collections (Nagoshi et al, 2017b). However, fewer moths from bucket traps were COI-RS than COI-CS (v 2 = 9.4, P = 0.0028).…”

“…Larvae 74 (Nagoshi et al, , 2015, Texas, USA (TX) (Nagoshi et al, 2011), Florida, USA (FL) (Nagoshi et al, 2011), Puerto Rico (PR) (Nagoshi et al, 2015), Togo 2016 (larvae) (Nagoshi et al, 2017b), and Togo 2017 (traps) from this paper.…”

High-depth resequencing reveals hybrid population and insecticide resistance characteristics of fall armyworm (Spodoptera frugiperda) invading China

“…Recent studies have indicated that the molecular identification of the two strains of fall armyworm is dependent on which markers are used [35][36][37] . The early molecular markers based on mitochondrial Cytochrome Oxidase Subunit I (COI) and Z-chromosome-linked Triosephosphate isomerase (Tpi) genes failed to accurately assign strain identification [38][39][40][41] . The dominant population of fall armyworm invading Africa and Asia were speculated to be hybrid populations of the female R-strain and male C-strain, based on these two molecular markers 42 .…”

Multiple incursion pathways forHelicoverpa armigerain Brazil show its genetic diversity spreading in a connected world

“…The rapid spread and establishment of H. armigera across much of the South American continent has generated a very large population with significant impacts on agricultural production. In contrast to usual invasions such as the African incursion of the New World fall armyworm S. frugiperda [16,34,[39][40][41][42], the invasive H. armigera population in the New World appears to be very diverse. Furthermore, the spatial distribution of this diversity strongly suggests that the population has spread from two different regions of introduction.…”