Donald J. Lee

Population Variation of the Fall Armyworm, Spodoptera frugiperda, in the Western Hemisphere

Abstract Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), the fall armyworm is the most economically important maize pest in the western hemisphere. This research focused on the genetic variability of the maize host strain because there is a lack of information in this area of S. frugiperda research. Amplified fragment length polymorphism (AFLP) was used to assess the genetic variability of S. frugiperda over a large geographic area. Twenty populations were collected from the maize, one population was collected from princess tree, one population was collected from lemon tree, and one population was collected from bermudagrass. The 23 populations were from Mexico, the continental United States, Puerto Rico, Brazil, and Argentina. The objective of this research was to evaluate whether the majority of genetic variability was within populations or between populations. The AFLP results showed that the majority of the genetic variability is within populations and not between populations, indicating minor gene flow and suggesting that S. frugiperda in the Western Hemisphere are an interbreeding population.

Genetic Variability of the European Corn Borer, Ostrinia nubilalis, Suggests Gene Flow Between Populations in the Midwestern United States

Abstract The European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), is a widely distributed and serious economic pest to corn production in the U.S. Genetic variability of O. nubilalis was studied in 18 sub-populations in the upper Midwestern United States using amplified fragment length polymorphism. The relatively low GST values indicate that more variation exists within populations than between populations. High gene flow (Nm) values were indicated across the entire O. nubilalis population; the lowest degree of gene flow was in the northern samples (Nm = 1.96) and the highest degree of gene flow was in the southern samples (Nm = 2.77). The differences observed in the respective regions (north vs. south) may be explained by the voltinism patterns (univoltine vs. multivoltine, respectively) of O. nubilalis: southern multivoltine populations have opportunities for multiple matings for the duration of the year, further mix alleles. AMOVA results also indicated that most of the genetic variation was within sub-populations (≈ 81% of total variation); less variation (≈ 13%) was detected among populations within each of the three regions as designated for this study. However, the most striking and unexpected result was the low percentage of variation between all groups (≈ 6%), further supporting implications of a high degree of gene flow. These results provide support for current requirements of refugia corn planting in Bt-corn management. These results also indicate that if resistance to Bt were to evolve in O. nubilalis, quick action would be necessary to deter the rapid spread of the gene for resistance.

Growth and fitness components of wild × cultivated Sorghum bicolor (Poaceae) hybrids in Nebraska.

UNLABELLED PREMISE OF THE STUDY Gene flow from crops to wild relatives has received considerable attention since the advent of genetically modified crops. Numerous researchers have found wild-crop hybrids to be nearly as fit as their wild parents, which suggests that crop genes may persist in wild populations. Components of the ecological fitness of cultivated sorghum, its wild relative, shattercane, and their hybrids have not been studied. • METHODS To assess the potential for gene introgression into shattercane, we crossed cultivated sorghum to a single inbred shattercane line to produce F(1) hybrids and measured growth and several components of ecological fitness in relation to both parents in Nebraska, USA. • KEY RESULTS Germination of F(1) seeds was similar to that of its shattercane parent except at high temperatures, where it was as sensitive as the sorghum parent. The F(1) grew taller and produced more biomass than either parent, but the F(1) leaf area index was intermediate. Fecundity of the F(1) plant was similar to that of shattercane and much greater than that of cultivated sorghum. • CONCLUSIONS Considering all data, the ecological fitness of shattercane × cultivated sorghum F(1) hybrids may be equivalent to the wild shattercane parent, which suggests that crop genes that are either neutral or beneficial to shattercane would persist in populations within agroecosystems.

Using the ASSIST Short Form for Evaluating an Information Technology Application: Validity and Reliability Issues

In this study, the Approaches and Study Skills Inventory for Students (ASSIST) short form was used to gain insight about learning style characteristics that might influence students’ use of an online library of plant science learning objects. This study provides evidence concerning the internal consistency reliability and construct validity of the Deep, Strategic and Surface scale scores when used to sort students’ responses. Participants consisted of 446 resident university students (230 males, 216 females) in agricultural science courses with face-to-face instruction supplemented with web-based lessons. Cronbach’s alphas for the three scales ranged from 0.65 to 0.75. The data file was submitted to a maximum likelihood factor analysis with oblimin rotation. When three factors were extracted, all 18 items loaded on the expected factors. One example of an analysis based on ASSIST scale scores is presented to show the potential of this procedure for helping with the interpretation of student comments.

Organellar genetic diversity in Penstemon haydenii (Scrophulariaceae): an endangered plant species

Genetic variation was analyzed in the endangered prairie forbPenstemon haydenii. Individuals from nine populations weresurveyed for chloroplast DNA (cpDNA) and mitochondrial DNA (mtDNA)variation. No cpDNA polymorphism was found. Analysis of mtDNA revealedvariation within and among populations. A minimum of eight haplotypeswere identified. The distribution of these genotypes suggests that thereis some correlation between geographic and genetic distances, whichreflects the minimal gene flow in thisspecies.

Increasing public understanding of transgenic crops through the World Wide Web

Transgenic crops are among the most controversial “science and society” issues or recent years. Because of the complex techniques involved in creating these crops and the polarized debate over their risks and benefits, a critical need has arisen for accessible and balanced information on this technology. World Wide Web sites offer several advantages for disseminating information on a fast-changing technical topic, including their global accessibility; and their ability to update information frequently, incorporate multimedia formats, and link to networks of other sites. An alliance between two complementary web sites at Colorado State University and the University of Nebraska-Lincoln takes advantage of the web environment to help fill the need for public information on crop genetic engineering. This article describes the objectives and features of each site. Viewership data and other feedback have shown these web sites to be effective means of reaching public audiences on a complex scientific topic.

Chloroplast DNA evidence for non-random selection of females in an outcrossed population of soybeans (Glycine max (L.)) *

SummaryRestriction fragment length polymorphisms (RFLPs) were used to assess chloroplast DNA (cpDNA) variation in a population of soybeans subjected to continuous cycles of forced outcrossing. This population was derived by crossing 39 female lines with four male-sterile (Ms2ms2) maintainer lines and advancing each generation by selecting only outcrossed seed borne on male-sterile (ms2ms2) plants. Analysis of the original 39 female lines revealed three groups based on cpDNA RFLPs. These three groups had been previously documented in soybeans, and the distribution of these groups among the female parents of this population was similar to that observed in germ plasm surveys of soybean. Thirty-four of the female parents had group I cpDNA, 3 had group II, and 2 had group III. Plants collected from this population after seven cycles of outcrossing were scored for four morphological traits (flower color, pubescence color, seed color, and pubescence type) known to be controlled by alleles at single nuclear loci. The frequencies of the phenotypes observed in this study indicated that the population underwent random mating with respect to flower and pubescence color, but deviated from random mating at the other two loci. Analysis of 158 of these same plants collected from the population after seven cycles of outcrossing revealed no individuals with group II or group III cpDNAs. The fixation of the group I cpDNA marker in this outcrossing population was judged to result primarily from selection against individuals in the population with the rare cpDNAs.

Population Genetics of the Western Bean Cutworm (Lepidoptera: Noctuidae) Across the United States

ABSTRACT The western bean cutworm, Striacosta albicosta (Smith), is a secondary pest of maize (Zea mays L.) and dry beans (Phaseolus vulgaris L.) in the western United States. Recently, this insect has undergone a major territory expansion into the eastern United States and has become a pest throughout much of the Corn Belt. This study was instigated to examine the population genetics of this pest to facilitate control and resistance management, as well as to shed light on the current habitat expansion. S. albicosta individuals were collected from 24 different locations across the traditional and expanded range and amplified fragment length polymorphism analysis was conducted to assess genetic variability. In total, 90 markers were analyzed, encompassing >90% of genetic variation. Gst across all locations was moderately high (Gst = 0.5032). AMOVA analysis revealed that the majority of genetic variation was within locations (54%) and among locations within groups (45%) indicating genetic differentiation of subpopulations. The Mantel test revealed no correlation between geographic and genetic distance (n = 548; r = 0.0045; P = 0.4350). Locations sampled in the eastern United States did not exhibit any reduction in genetic variation in comparison to locations sampled in the western United States, so we conclude that no bottleneck event has occurred with this territory expansion.

Population structure, genetic variability, and gene flow of the bean leaf beetle, Cerotoma trifurcata , in the Midwestern United States

Abstract Bean leaf beetle, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), is a common pest of soybean in the Midwest United States. However, there are currently no reports on the genetic variability of C. trifurcata . This study examined 15–30 individuals from 25 sample locations to estimate genetic variability and gene flow within and among C. trifurcata from across the Mid- west. Amplified fragment length polymorphism generated 175 markers for analyses. Results from analysis of molecular variance (AMOVA) indicated that the majority of genetic variation was from within samples; only a small amount of the total variation was attributed to the variation among the samples. The GST for the entire C. trifurcata population indicated that the majority of genetic variation was found within the samples, further supporting the AMOVA results. The estimated average gene flow among the C. trifurcata samples was 1.83. The Mantel test revealed no indication of correlation between geographical and genetic distance for all the C. trifurcata samples. These findings show that C. trifurcata in the Midwest are genetically heterogeneous and part of a large, interbreeding population.

Sequence-characterized amplified regions that differentiate New World screwworms from other potential wound-inhabiting flies.

New World screwworms, Cochliomyia hominivorax (Coquerel, 1858), were once devastating pests of warm-blooded animals in the United States before they were successfully eradicated using the sterile insect technique. Guarding against the introduction of screwworms to North America or any other screwworm-free area relies on rapid, reliable identification of suspected cases. In the current study, the DNA from excised markers generated by randomly amplified polymorphic DNA polymerase chain reaction was used as the basis to generate 2 species-specific sequence-characterized amplified region molecular markers. Resulting primer pairs, named CR92A1 and J1A2 (each with forward and reverse components), produced amplicons of 852 and 848 base pairs, respectively. The 2 primer pairs successfully discriminated between C. hominivorax, Cochliomyia macellaria (Fabricius, 1775), 8 other species of blowflies, 3 noncalliphorid dipterans, and 1 nondipteran outlier. These primers may become important tools for veterinary laboratories and the screwworm eradication and exclusion program for rapid identification or verification of suspicious larval samples in presumed outbreaks.