Spatial Genetic Variation among Spodoptera frugiperda (Lepidoptera: Noctuidae) Sampled from the United States, Puerto Rico, Panama, and Argentina

Abstract

ARSTRACT Spatial genetic variability of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), was studied by collecting samples from 31 locations in the United States, Argentina, Panama, and Puerto Rico, and then using amplified fragment length polymorphism to detect genetic variation. Analysis of molecular variance showed significant genetic variation in fall armyworm among all (28%) sample locations and individuals within (71%) sample locations; genetic variation of fall armyworm was minimal between sample locations grouped into regions. The pairwise fixation index (FST) comparisons showed significant genetic differentiation (0.288) among the 31 locations. However, dendrograms of results from cluster analysis did not provide support of a high level of genetic structuring among regions. The isolation by distance analysis for all sample locations showed the absence of significant correlation between genetic dissimilarity and geographic distance except for fall armyworm samples collected within Argentina. Moreover, the estimate of modest gene flow (Nm >1) may prevent gene fixation within regions. These results indicate that fall armyworm shows little genetic differentiation and high genetic diversity over its range, important information for the development of management strategies and monitoring the development of resistance to management techniques.

Population structure of Spodoptera frugiperda maize and rice host forms in South America: are they host strains?

“…The highest amount of diversity was found among individuals and the correlation analysis confirmed no genetic isolation by geographic distance between S. frugiperda populations, which is in agreement with Martinelli et al (2007), Clark et al (2007), and Belay et al (2012). This poses the question of what maintains this genetic differentiation: geographical distance, host fidelity, or strain identity, and how they are related.…”

“…In South American populations there seem to be some differences, as we recently found no consistent pattern of host association between the two forms and their respective host plants when using two restriction site polymorphisms in COI (Ju arez et al, 2012). Most of the work published using molecular markers has been used to identify both forms and assess their host specificity, but provide little information about the genetic diversity and population structure of S. frugiperda, with a few exceptions (McMichael & Prowell, 1999;Busato et al, 2004;Clark et al, 2007;Belay et al, 2012). In using this combination, about 16% of field-collected samples from Louisiana, Florida (both USA), Puerto Rico, Guadeloupe, and French Guiana (Prowell et al, 2004) were found to be potential hybrids due to discordance for at least one marker (mtDNA, esterase, and AFLP), with both types of hybrids (RC and CR; first letter always referring to the female) equally frequent, mostly in maize habitats.…”

“…These markers include differences in mtDNA sequences identified in the cytochrome oxidase I (COI), and NADH dehydrogenase genes (Pashley, 1989;Lu & Adang, 1996;Levy et al, 2002;Nagoshi et al, 2006a), as well as nuclear DNA differences, including restriction length fragment polymorphisms (RFLPs) (Lu et al, 1992), amplified fragment length polymorphisms (AFLPs) (McMichael & Prowell, 1999;Busato et al, 2004;Clark et al, 2007;Martinelli et al, 2007;Belay et al, 2012), polymorphisms in tandem-repeat sequences (FRs) (Lu et al, 1994;Nagoshi & Meagher, 2003a,b), and 10 polymorphisms in the sex-linked triose phosphate isomerase gene (Tpi) (Nagoshi, 2010). These markers include differences in mtDNA sequences identified in the cytochrome oxidase I (COI), and NADH dehydrogenase genes (Pashley, 1989;Lu & Adang, 1996;Levy et al, 2002;Nagoshi et al, 2006a), as well as nuclear DNA differences, including restriction length fragment polymorphisms (RFLPs) (Lu et al, 1992), amplified fragment length polymorphisms (AFLPs) (McMichael & Prowell, 1999;Busato et al, 2004;Clark et al, 2007;Martinelli et al, 2007;Belay et al, 2012), polymorphisms in tandem-repeat sequences (FRs) (Lu et al, 1994;Nagoshi & Meagher, 2003a,b), and 10 polymorphisms in the sex-linked triose phosphate isomerase gene (Tpi) (Nagoshi, 2010).…”

“…The two host forms of S. frugiperda can be identified by a number of genetic markers. These markers include differences in mtDNA sequences identified in the cytochrome oxidase I (COI), and NADH dehydrogenase genes (Pashley, 1989;Lu & Adang, 1996;Levy et al, 2002;Nagoshi et al, 2006a), as well as nuclear DNA differences, including restriction length fragment polymorphisms (RFLPs) (Lu et al, 1992), amplified fragment length polymorphisms (AFLPs) (McMichael & Prowell, 1999;Busato et al, 2004;Clark et al, 2007;Martinelli et al, 2007;Belay et al, 2012), polymorphisms in tandem-repeat sequences (FRs) (Lu et al, 1994;Nagoshi & Meagher, 2003a,b), and 10 polymorphisms in the sex-linked triose phosphate isomerase gene (Tpi) (Nagoshi, 2010). Although restriction site polymorphisms in COI have been widely accepted to be the most suitable to characterize populations and assess host association with their respective plants, recently 10 SNPs in the Tpi gene have been proposed to be more consistent than COI for these purposes (Nagoshi, 2012).…”

Diversidade molecular entre populações de Spodoptera frugiperda no Brasil avaliada por marcadores AFLP

“…Portanto, devem-se utilizar marcadores que não requeiram conhecimento prévio sobre o genoma. Entre estes, o "amplified fragment length polymorphism" (AFLP) possibilita caracterizar biótipos e detectar a variabilidade genética de S. frugiperda (Busato et al, 2004;Clark et al, 2007;Martinelli et al, 2007;Belay et al, 2012) Creste et al (2001). A separação dos fragmentos foi realizada em eletroforese por 2 horas, a 60 W.…”