Claims of disproportionate numbers of spiders in certain homes and public demand for non-pesticide means of pest control fostered a closer look at whether landscaping and the manipulation of yards can have an influence on spider migration into homes. Typically, spiders are unwanted houseguests, and homeowner concern over potential contacts with spiders poses challenges to acceptance of these beneficial animals. A 2-year survey was conducted to determine if the complexity of landscaping surrounding a home influences the diversity and abundance of spiders entering houses. The survey consisted of simple and complex landscapes in a regional area. Complexly planted yards had significantly higher numbers of spiders and greater diversity of spider taxa in houses, suggesting a correlation between landscape density and spider invaders. Species data include those that are synanthropic throughout the United States as well as species that are seasonal home invaders. In all, 804 spiders were collected, with 26 species and 31 genera. Results of this 2-year survey will be presented.
I.E. Yates and Darrell Sparks
Mycotoxins harmful to humans and other animals are produced in kernels of sweet corn (Zea mays L.) during colonization by the fungus Fusarium verticillioides (Sacc.) Nirenberg. Experimentation is limited under field conditions, due to the seasonality of the organisms, to once each year in temperate climates and under greenhouse conditions by the number of plants that can be grown. The objective of this study was to examine grocer ears (pistillate inflorescence) from retail stores as an alternative source for experimental material to use in bioassays to study this important food safety problem. Fusarium verticillioides migration was compared in sweet corn ears from a local grocery store and from greenhouse and field plants. Ears were inoculated with a F. verticillioides transformant tagged with a selection gene encoding resistance to hygromycin, a fungicidal antibiotic, and with a reporter gene encoding for ß-glucuronidase, an enzyme detectable by histochemical staining. Screening kernels for both genes ensures unequivocal identification of the source of subsequent mycelia. Fusarium verticillioides colonized sweet corn ears towards the ear apex and base from the inoculation site regardless of ear source, incubation protocol, or attachment of the ear to the plant or to the shuck (spathe) and silks (styles) to the ear. Thus, ears from retail grocers can serve as experimental material for analyzing sweet corn and F. verticillioides interactions throughout the year.
Zhi Quan, Bin Huang, Caiyan Lu, Yi Shi, Yanhong Cao, Yongzhuang Wang, Chuanrui He, Guangyu Chi, Jian Ma and Xin Chen
migration to a deeper soil layer or groundwater when the conditions are satisfied ( Bergström and Kirchmann, 1999 ). High-input cropping systems, especially greenhouse cultivation, develop quickly in China to meet consumer demand for vegetables throughout
Ping Lang, Fenny Dane, Thomas L. Kubisiak and Hongwen Huang
The genus Castanea (Fagaceae), which contains three sections and seven species, is widely distributed in the deciduous forests of the Northern Hemisphere. The phylogeny of Castanea was estimated using DNA sequence data from five different regions of the chloroplast genome. Sequencing results support the genus Castanea as a paraphyletic group with C. crenata, the Japanese chestnut, representing an early divergence in the genus. The three Chinese species form a strongly supported sister clade to the North American and European clade. A unique westward expansion of extant Castanea species is hypothesized with Castanea originating in eastern Asia, an initial diversification within Asia during the Eocene, followed by intercontinental dispersion and divergence between the Chinese and European/North American species during the Oligocene and a split between the European and North American species in the early Miocene. The differentiation within North America and China might have occurred in late Miocene or early Pliocence. The North America species are supported as a clade with C. pumila var. ozarkensis, the Ozark chinkapin, as the basal lineage, sister to the group comprising C. pumila var. pumila, the Allegheny chinkapin, and C. dentata, the American chestnut. Morphological evolution of one nut per bur in the genus may have occurred independently on two continents.
Microsporogenesis was studied in 42 randomly chosen Fz plants of garden asparagus (Asparagus officinalis L. cv. UC 157) (2n = 2x = 20) that had been previously screened for production of pollen of heterogeneous size. At the tetrad stage, the average frequencies of tetrads, triads, and dyads were 58.9%, 15.4%, and 25.9%, respectively. Dyads and triads originated from the lack of chromosome migration toward opposite poles at anaphase II in either one or both cells of a microsporocyte, followed by the absence of cytokinesis in telophase II. The resulting 2n microspores were, therefore, genetically equivalent to second meiotic division restitution products. The observation that all plants examined produced 2n microspores in high frequencies is taken as an indication that the modified meiosis in these plants is under genetic control.
Virginia D. Lerch and Timothy Ng
Since the introduction of New Guinea impatiens in 1980 the genus Impatiens has remained the number one selling bedding plant in the U.S. However, basic information concerning the genus is lacking. This study was undertaken to estimate genetic and phenotypic diversity within species and groups of an Impatiens germplasm collection representing seven countries. It includes plants from the 1970 plant expedition co-sponsored by USDA-ARS and the Longwood Foundation (Kennett Square, PA); donations from the Royal Botanic Gardens (Kew, England); and ovule cultured interspecific hybrids created by Dr. Toru Arisumi (USDA, Beltsville, MD). The collection was grown in a common environment and characterized for 31 qualitative and quantitative morphological traits, and electrophoretically characterized for several enzymes using polyacrylamide gel electrophoresis. Evidence concerning putative interspecific hybrids and relationships among Impatiens groups based on morphological and electrophoretic characterization and diversity indices will be presented. Isozyme patterns lending support to hypotheses of center of origin, migration and evolution of Impatiens will also be discussed.
William Spencer and Justin Williams
The state of Texas consists of roughly 4800 species of vascular plants. In 1970, it was estimated that 200 of these were introduced species. By 2003, the number of introduced species almost doubled to 350. Using the Atlas of the Vascular Plants of Texas, a database was compiled listing the invasive species in Texas and which of the 254 counties they inhabited. This database was then converted into a GIS platform that allowed us to analyze those data spatially. With these data, we were able to calculate the actual number of invasive species per county. In addition, these data were used to predict possible points of invasive species introduction, the rate of spread for certain problematic species, routes of migration, and to isolate counties under threat of possible infestation.
Cynthia B. McKenney and Ellen B. Peffley
Proponents of distance education encourage the migration of courses and entire degree programs onto the web. To this end, vast amounts of time, energy, and funds are directed to the development of new courses as well as the enhancement of traditionally taught courses. The question now begs to be asked, “Are we getting what we truly want from distance education?” Using a web platform provides a framework with excellent options to develop audio and visually rich courses. Distance programs also provide access to students not able to participate in traditional on-campus degree plans, providing the potential for a boost in enrollment. However, there are serious considerations that need to be balanced, including student satisfaction/dissatisfaction, enrollment management, faculty time commitment, and technical support. In this presentation, some of the benefits and liabilities of web courses will be discussed and program management suggestions will be explored.
Dan E. Parfitt, M.L. Badenes and R.G. Fjellstrom
Chloroplast DNA polymorphisms were obtained using a combination of RFLP analysis of total cpDNA and a combination of PCR amplification restriction of a 3.2-kb region of cpDNA described previously. Nuclear genome analysis was conducted using 21 RFLP probes that revealed 192 alleles. Parsimony analysis of nuclear DNA places J. cinerea between J. regia and other Asian species, while Wagner-Distance analysis places all North American species between them. cpDNA parsimony also placed the North American species between J. regia and remaining Asian species, but did not resolve the placement of J. cinerea, because all North American species were monomorphic. Both analyses support an ancient origin for J. regia and multiple migration events between North America and Asia.
Davide Neri, Gianpaolo Mascanzoni, Paolo Sabbatini, Franco Zucconi and James Flore
To simulate soil sickness, 1-year-old trees of `Golden Delicious' (grafted on M9 and M106) were grown in rhizotrons (1 × 1-m and 0.5-m depth) with different plant residues content, at Ravenna, Italy. Sandy loam soil was used as a substrate. Fine-grounded wood from apple and peach residues (6 kg per rhizotron) was mixed to the substrate and considered as main treatment. Mature compost (1% and 2.5% in volume) was added or not to the substrate with the organic residues and considered as subtreatment. The application of residues was localized either near the soil surface (0–25 cm) or deeper in the soil profile (25–50 cm). In each rhizotron, four trees on the same rootstock were planted and each soil treatment was replicated twice. After 2 years, the roots were accurately excavated (washing off the soil with water), and growth was measured. The presence of apple residues near the soil surface induced a 5% to 20% reduction of shoot growth. The reduction per plant dry weight was higher when trees were grafted on M106. At root level, the presence of residues increased the root migration in the search for fresh niches, enhancing root crossing and anastomosis. Both these shoot and root conditions are typical of replant diseases symptoms. The localization of apple residues in the lower part of the profile reduced the symptoms and so did the addition of compost. The peach residues did not affect shoot growth when compared to the control, but the shoot-to-root ratio was reduced, indicating a tendency to increase root migration.