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

Abstract

The Old World cotton bollworm Helicoverpa armigera was first detected in Brazil with subsequent reports from Paraguay, Argentina, Bolivia, and Uruguay. This pattern suggests that the H. armigera spread across the South American continent following incursions into northern/central Brazil, however, this hypothesis has not been tested. Here we compare northern and central Brazilian H. armigera mtDNA COI haplotypes with those from southern Brazil, Uruguay, Argentina, and Paraguay. We infer spatial genetic and gene flow patterns of this dispersive pest in the agricultural landscape of South America. We show that the spatial distribution of H. armigera mtDNA haplotypes and its inferred gene flow patterns in the southwestern region of South America exhibited signatures inconsistent with a single incursion hypothesis. Simulations on spatial distribution patterns show that the detection of rare and/or the absence of dominant mtDNA haplotypes in southern H. armigera populations are inconsistent with genetic signatures observed in northern and central Brazil. Incursions of H.armigera into the New World are therefore likely to have involved independent events in northern/central Brazil, and southern Brazil/Uruguay-Argentina-Paraguay. This study demonstrates the significant biosecurity challenges facing the South American continent, and highlights alternate pathways for introductions of alien species into the New World.

Whole‐genome sequencing to detect mutations associated with resistance to insecticides and Bt proteins in Spodoptera frugiperda

“…Partial mitochondrial DNA genes together with partial Tpi gene characterization of FAW populations from the New World and various sub‐Saharan African countries have suggested limited introduction of FAW into Africa and point toward Florida and the Greater Antilles as a source population (Nagoshi et al ., 2018, 2019). For the related noctuid H. armigera , the use of multiple partial genes as markers and/or single gene incorporating simulation have enabled inference of potential incursion pathways (e.g., trade‐related, Tay et al ., 2017; and introduction frequencies, Arnemann et al ., 2019). Nevertheless, there is increasing use of WGS approaches, as exemplified by this study, for understanding invasive populations’ resistance profiles and to identify novel resistance alleles.…”

Adaptive Introgression across Semipermeable Species Boundaries between Local Helicoverpa zea and Invasive Helicoverpa armigera Moths

“…2018 ; Mallet 2018 ; Tay and Gordon 2019 ) and there is evidence for initial independent incursions, centered on numerous geographic locations ( Tay et al. 2017 ; Arnemann et al. 2019 ).…”

“…Multiple and likely ongoing introductions of H. armigera from the Old World mean that the genetic diversity of the New World populations is very high and possibly comparable to that in the species’ ancestral range ( Tay et al. 2017 ; Arnemann et al. 2019 ; Gonçalves et al.…”

One maternal lineage leads the expansion of Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae) in the New and Old Worlds

“…The mtDNA is inherited most often only from the mother and does not undergo recombination 41 , enabling to assess the number of genetically unique founder females [42][43][44][45] . Studies of invasive species used similar methodologies, for example of T. peregrinus 16 , wood-boring beetles 46 , Melanagromyza sojae (Zehntner, 1900) (Diptera: Agromyzidae) 47 and Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae) 48 .…”