Other Environmental Sciences Commons^™

Comparison Of Canopy Temperature-Based Water Stress Indices Formaize, Kendall C. Dejonge, Saleh Taghvaeian, Thomas J. Trout, Lousie H. Thomas

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Infrared thermal radiometers (IRTs) are an affordable tool for researchers to monitor canopy tempera-ture. In this maize experiment, six treatments of regulated deficit irrigation levels were evaluated. Themain objective was to evaluate these six treatments in terms of six indices (three previously proposedand three introduced in this study) used to quantify water stress. Three are point-in-time indices whereone daily reading is assumed representative of the day (Crop Water Stress Index – CWSI, Degrees AboveNon-Stressed – DANS, Degrees Above Canopy Threshold – DACT) and three integrate the cumulativeimpact of water stress over time (Time Temperature Threshold – TTT, Integrated Degrees Above …

Fitness Costs Of Resistance To Cry3bb1 Maize By Western Corn Rootworm, A M. Hoffmann, B W. French, R L. Hellmich, N Lauter, A J. Gassmann

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Crops producing toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage insect pests including western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), which is a significant pest of maize in the United States and Europe. However, the widespread use of Bt maize places intense selection pressure on pest populations to evolve resistance, and field-evolved resistance to Bt maize by western corn rootworm has been documented in the United States. In conjunction with non-Bt refuges, fitness costs of Bt resistance can delay resistance evolution. Fitness costs arise in the absence of Bt toxin when individuals with …

Clonal Integration In Ludwigia Hexapetala Under Different Light Regimes, Rachael Glover, Rebecca E. Drenovsky, Caryn J. Futrell, Brenda J. Grewell

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Physiological integration among ramets of invasive plant species may support their colonization and spread in novel aquatic environments where growth-limiting resources are spatially heterogeneous. Under contrasting light conditions, we investigated how clonal integration influences growth, biomass allocation and morphology of Ludwigia hexapetala, an emergent floating-leaved macrophyte that is highly invasive in a range of wetland habitat types. In aquatic mesocosms, stolons of offspring ramets were either connected or severed from parent plants, with the pairs exposed to homogenous or heterogeneous combinations of sun or 85% shade. Morphological traits of all ramets were strongly influenced by light environment, and low light …

The Importance Of Olfactory And Visual Cues In Developing Better Monitoring Tools For Sirex Noctilio (Hymenoptera: Siricidae), Mark A. Sarvary, Miriam F. Cooperband, Ann E. Hajek

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

1. To improve the monitoring of the invasive European woodwasp, both sexes of Sirex noctilio were studied in a walk-in wind tunnel.We evaluated three trap types: unbaited traps, traps baited with a three-component pheromone lure and traps baited with a commercial Sirex kairomone lure and ultraviolet light.

2. When no lure was present, the black intercept trap caught more females than the clear jar trap. The increase in pheromone concentration from 0.1 to 1mg increased the capture of females, and not males, in the black intercept panel trap. Both of these findings suggest that the visual cues provided by the …