Environmental Sciences Ph.D. (EVS) Student Publications
Student Research and Publications
Current Students:
Peter W. Blum
Concentration: Biology
- Horizontal distribution affects the vertical distribution of native and invasive container
inhabiting Aedes mosquitoes within an urban landscape (co-author) 2020
Abstract: Mosquitoes breed in temporary bodies of water that are distributed horizontally through the landscape, from puddles at ground level to tree holes high above the forest floor. We found that two species of mosquitoes of container-breeding mosquitoes varied in their preference of height of breeding containers dependent on habitat and a fine spacial scale. - Mesohabitat current velocity effects on Didymosphenia geminata and macroinvertebrates
in a SE USA hypolimnetic tailwater. (co-author) 2019
Abstract: The diatom, Didymosphenia geminata (didymo), forms mats that reduce microhabitat heterogeneity for freshwater macroinvertebrates. We found shifts in macroinvertebrates communities for food utilization and habitat availability resulting from didymo mat formation in the tailwaters below a hypolimnetic dam.
Martine Bowombe-Toko
Concentration: Agriculture
- Monitoring of Tribolium castaneum (Coleoptera: Tenebrionidae) in rice mills using pheromone-baited traps (2019)
Abstract: The red flour beetle is an important pest of rice mills, but there is comparatively less information about its distribution and seasonal patterns of activity in rice mills compared to patterns in wheat flour mills. Using pheromone traps to sample red flour beetle populations in and around four rice mills in Arkansas over a two-year time period, it was shown that although there was considerable variation among mills, overall fewer beetles were found in rough rice storage areas compared to inside the mill. More beetles were trapped during the spring and summer months compared to autumn and winter. Using a target threshold for beetles captured that was previously developed to indicate an increased risk, it was found that most captures in all the mills were below this level. Temperatures inside the mills tended to follow outside temperatures, but to be about 1 degree Celsius warmer than outside. With the level of variation in red flour beetle captures among trap locations observed, this study illustrates that having a monitoring program for each particular facility is an important tool for rice processing facilities. The utilization of pheromone traps could provide information to mill managers to determine locations within a mill that are most vulnerable to infestation and to assist with the timing and targeting of control interventions. - Stored-Product Insects Associated with On-Farm Storage in Northeast Arkansas
Abstract: Integrated pest management (IPM) is important to reduce loss and damage to stored bulk rough rice. One component of IPM is to know how insect populations fluctuate over time. We therefore conducted a study from June to November, 2013 on four on-farm rice storage facilities in northeast Arkansas to examine the temporal and spatial distribution of stored-product insects. The warehouse beetle (Trogoderma variabile) and lesser grain borer (Rhyzopertha dominica) were the two most abundant beetles found at all locations. Indianmeal moths (Plodia interpunctella) and red flour beetles (Tribolium castaneum) were also present, but in lower numbers. Interestingly, stored-product insects were very abundant throughout the summer even when rice was not stored at these facilities.
Ronnie J. Dunn
Concentration: Agriculture
- Response of Hydroponic Tomato Yield and Yield-correlated Morphological Characteristics
to Constant or Growth Stage-based Nutrient Management Strategies
Abstract: In the United States, the annual revenue attributable to tomato production is $1 billion. However, tomato production can cause negative environmental impacts, such as water pollution, often in the form of eutrophication-causing nutrient pollution. Hydroponic production can decrease excess nutrient leaching; however, optimization of nutrient management and cultivar choices could further decrease excess nutrient discharges. The objectives of this study were as follows: to evaluate and compare the responses of tomato growth characteristics, yield, and yield components to two nutrient management regimes (varying nutrient solution concentrations by growth stage and the use of a constant nutrient solution concentration from transplant to termination), and to analyze the effects of growth habits among six cultivars (Big Beef, Cherokee Purple, Heatmaster, Legend, Mountain Fresh Plus, and Tropic) on tomato yield and yield-correlated morphological characteristics. The nutrient management strategies were applied to tomato plants, and data regarding yield and related morphological characteristics were obtained. Data were analyzed using SAS PROC GLM. An analysis revealed no significant difference in the total fruit weight/plant between nutrient management regimes (P = 0.05); however, the mean fruit weight (164.26 g) and diameter (71.70 mm) were significantly greater (P < 0.0001) for plants that received the constant concentration nutrient regime. Indeterminate plants had a significantly greater (P < 0.0001) mean fruit weight (192.76 g) and mean fruit diameter (76.42 mm). Among cultivars, Big Beef had a significantly greater (P < 0.05) total fruit weight/plant (9.25 kg). Applying a constant nutrient concentration to indeterminate cultivars, particularly Big Beef and Cherokee Purple, improved the factors analyzed and could decrease negative environmental impacts while increasing profits of the producers.
Sahar Salimi
Concentration: Integrated Research
- Characterization and organization of telomeric-linked helicase (tlh) gene families in Fusarium oxysporum
Abstract: Telomere-linked RecQ helicase (tlh) genes have been reported in several fungi and a choanofagellate in the regions adjacent to the terminal telomere repeats. In this study, we explored the Telomere-linked RecQ helicase (tlh) genes in four strains of Fusarium oxysporum, offering new insights into their genomic structure, functional motifs, and impact on chromosomal ends. We conducted a comprehensive analysis, comparing the tlh genes of F. oxysporum with those previously identifed in other organisms and uncovering signifcant similarities. Through comparative genomics, we identifed conserved protein motifs across these genes, including a TLH domain, C2H2, and RecQ helicase motifs. Our phylogenetic analysis positions the F. oxysporum tlh genes in a cluster with other known tlhs, suggesting a shared evolutionary origin. Mutation analysis revealed a relatively low level of deleterious mutations in tlh gene paralogs, with a notable proportion of full-size structures maintained across strains. Analysis of subtelomeric sequences indicates that a region with almost identical sequences fanks the majority of chromosome ends, termed tlh-containing region (TLHcr), across these strains. The presence of TLHcrs at chromosome ends, either as single entities or in arrays, underscores their potential role in telomere function and genome stability. Our fndings provide a detailed examination of tlh genes in four strains of F. oxysporum, laying the groundwork for future studies on their biological signifcance and evolutionary history in fungal genomes.
