|Meagher, Robert - Rob|
Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/9/2005
Publication Date: 3/20/2006
Citation: Lewter, J.A., Szalanski, A.L., Nagoshi, R.N., Meagher Jr, R.L., Owens, C.B., Luttrell, R.G. 2006. Genetic variation within and between strains of the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae). Florida Entomologist. 89:63-68. Interpretive Summary: Limited information exists on genetic variation and distribution of the corn and rice strains of the fall armyworm (FAW). USDA, ARS Scientists at the Center for Medical, Agricultural and Veterinary Entomology conducted a study to investigate the when and where FAW occurs across a part of its range. Genes were sequenced from individuals from three corn and four rice strain types. Results indicated significant levels of genetic differentiation among populations both within and between the two fall armyworm strains. This research also represented the first attempt to determine the geographical distribution of fall armyworm strains using genetic sequence data as well as determining the extent of genetic variation within each strain. This information will ultimately lead to better targeting of area-wide controls.
Technical Abstract: Limited information exists on molecular genetic variation and distribution of the corn and rice strains of the fall armyworm, Spodoptera frugiperda (J.E. Smith). This study was conducted to investigate the genetic structure of S. frugiperda across a part of its range in the United States. A 608 base pair portion of the mitochondrial cytochrome oxidase I and II genes was sequenced from 71 individuals resulting in three corn and four rice strain haplotypes. Genetic divergence between the two strains ranged from 0.66 to 0.99%. A 562 base pair region of the nuclear ITS-1 gene was also amplified and sequenced from 17 individuals. No variation was detected in any of the samples, providing evidence of gene flow between the fall armyworm strains. Analysis of molecular variance was conducted on the resulting mtDNA haplotypes from the Arkansas and Florida populations and as a hierarchical analysis between populations in the two states. Results indicate a significant overall 'ST for all populations with the hierarchical analysis revealing that this significant 'ST is due to structuring of the populations between states. The observed genetic structure is possibly due to the distribution of fall armyworm strains.