Molecular Identification of the Fall Armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) Using PCR-RFLP

The fall armyworm, Spodoptera frugiperda, as with many noctuid moths, is a serious agricultural pest in the United States. Researchers often use pheromone traps to monitor for the presence of economically important noctuid pests. Pheromone traps may attract more than one species and samples often degrade, making morphological identification of some adult noctuid species nearly impossible. A molecular diagnostics protocol using polymerase chain reaction, restriction fragment length polymorphism (PCR-RFLP) was developed in order to distinguish the fall armyworm from six other noctuid species commonly found in Arkansas. A 611-bp region of the mtDNA COI, COII genes was amplified using PCR and then sequenced. The restriction enzymes Dra I, Alu Iand Nla III had specific restriction sites that distinguished the seven noctuid species. This proved to be a reliable, quick and economical technique for identifying the fall armyworm as well as six other noctuid species

Genetic Structure of Aedes vexans (Diptera: Culicidae) Populations from Central United States Based on Mitochondrial ND5 Sequences

Aedes vexans (Meigen), the vexans mosquito, is a species that prefers mammalian hosts and is a vector of West Nile virus (family Flaviviridae, genus Flavivirus). It is one of the most widespread pest mosquitoes in the world and North America, and it is commonly found in southern Canada and continental United States. Population structure of this species in Kansas was examined using DNA sequences of a 423-bp region of the mitochondrial NADH dehydrogenase subunit 5 (ND5) gene, relative to three other states. From the 54 Kansas samples, a total of 39 nucleotide positions were polymorphic, with 34 haplotypes. Of the 34 haplotypes, 22 (79%) were not shared among populations. The average haplotype diversity (0.953) from 11 Kansas populations indicated a high level of genetic diversity in Ae. vexans. Among the Kansas, South Dakota, Texas, and Louisiana samples, a total of 40 haplotypes were observed. Analysis of molecular variance was conducted on the resulting haplotypes for all populations and no geographical structure was observed among populations by using isolation-by-distance tests. This first genetic study of Ae. vexans provides evidence that there is a large amount of haplotype variation within and among populations, and gene flow occurs across broad geographical areas in this species. © 2006 Entomological Society of America

Development and Characterization of Molecular Markers Associated with Female Plants in Muscadine Grape

Muscadine (Vitis rotundifolia Michx.) vines may be male (M), female (F), or hermaphroditic (H). Male flowers have only filaments and anthers, whereas female and hermaphroditic flowers are morphologically perfect. Female flowers are distinguished from hermaphroditic flowers by their reflexed stamens (as opposed to upright) and nonfunctional pollen. Primers derived from previously identified candidate genes located at the sex locus of Vitis vinifera L. were used to generate amplicons from M, F, andHmuscadine cultivars. Sequence analysis of the amplicons revealed insertion/deletion (indel) polymorphisms in a trehalose-6-phosphate phosphatase (TPP) gene (VR006) and a WRKY transcription factor 21 gene (VR009). Primers were designed to create diagnostic markers for each indel polymorphism. Associations between the marker alleles and the plant sex trait were examined in a wide range of muscadine germplasm and in segregating populations derived from F × H, F × M, and H·× H crosses. VR006 produced a codominant marker that was able to differentiate the female-associated allele from the male-and hermaphroditicassociated alleles. The marker was able to detect female plants and will be suitable for screening breeding program progenies. VR009 was able to detect the presence of the female allele in most germplasm, but a crossover event appears to have separated the marker from the sex locus in some germplasm. As shown in previous muscadine genetic studies, H × H-derived populations produced male seedlings. Marker analysis of these populations indicates that male flowers only occur in seedlings which are heterozygous for F-and H-associated marker alleles and inheritance of flower type in muscadine remains unclear

Genetic Variation Within and Between Strains of the Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

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 representing both corn and rice strains. No variation was detected in any of the samples for the ITS-1 region. 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 ΦST for all populations with the hierarchical analysis revealing that this significant ΦST is due to structuring of the populations between states. The observed genetic structure is possibly due to the distribution of fall armyworm strains