OSU Theseshttps://hdl.handle.net/11244/104642024-03-29T03:05:47Z2024-03-29T03:05:47ZEffects of temperature and light cycle on the development of Aphelinus nigritus (Howard) in the Southern Great PlainsRudin, Ninahttps://hdl.handle.net/11244/3396092023-09-22T05:13:40Z2022-12-01T00:00:00ZEffects of temperature and light cycle on the development of Aphelinus nigritus (Howard) in the Southern Great Plains
Rudin, Nina
The Southern Plains of North America are a humid subtropical region. Drastic temperature changes are common, but multivoltine insects must adapt to allow their offspring to survive. In agricultural crops it is important to understand how climate and weather can influence pests and their natural enemies. With the introduction of sorghum aphids (Melanaphis sorghi) into the area, the abundance of Aphelinus nigritus has increased. Studies suggest a correlation between sugar cane aphid populations and A. nigritus parasitism rates, yet very little is known about this species developmental requirements or how they transition to and survive cold winter months.; This study consists of three experiments across two objectives. Objective i was to determine lower temperature thresholds and degree-day requirements for A. nigritus development and objective ii was to characterize the effects of photoperiod and temperature on A. nigritus development. In objective I microcosms were placed in one of four environmental chambers maintained at constant temperatures and one fixed light-dark cycle: 14, 18, 22, and 26ºC each at 16:8 L:D cycle. The number of days from oviposition to mummy, mummy to adult, and oviposition to adult were recorded, and each individual's developmental rate (1/days) was calculated for the three described developmental periods. Total development (Oviposition to Adult) ranged from 12.8-45.4 days. On average, the total degree day requirement of A. nigritus was 216.15 degree days with an average lower developmental threshold of 9.064ºC. In objective ii microcosms where maintained at one of 6 temperature fluctuation x day length environmental conditions (14-10ºC and 28-24ºC daily fluctuations each at 15:9 L:D, 12:12 L:D, and 9:15 L:D) to assess how these conditions influenced growth and development of offspring. We assessed the effect of parental exposure to environmental change and immature exposure to environment change. Results indicate that exposure to lower fluctuating temperatures and shorter days cause delays in development greater than those expected for A. nigritus. Delayed development associated with the onset of average winter conditions indicates that A. nigritus is entering oligopause.
2022-12-01T00:00:00ZEvaluation of potential paleochannels in the Washita Alluvium and Terrace aquifer, OklahomaSpears, Kylehttps://hdl.handle.net/11244/3396102023-09-22T05:10:45Z2020-12-01T00:00:00ZEvaluation of potential paleochannels in the Washita Alluvium and Terrace aquifer, Oklahoma
Spears, Kyle
Aquifers comprised of alluvium are often an important source of water for industrial, municipal, and environmental purposes. To best manage and protect these complex hydrogeologic systems, a comprehensive evaluation is needed to monitor and predict their response to stress. Electrical Resistivity Imaging (ERI) was used to image the subsurface architecture of the Washita Alluvium and Terrace aquifer in western Oklahoma up to 110 meter deep. This technique was applied to evaluate the geometry and hydraulic properties of the deposits, and integrated these data with limited well data available in the area.; The Washita Alluvium and Terrace aquifer overlies Permian-age bedrock, forming a boundary detectable by ERI. Previous investigations suggest the alluvial deposit was approximately 36 meters deep. The ERI data suggest a previously unknown paleochannel, up to 90 m deep is present in each of four cross section datasets that run perpendicular to the stream with lengths between 0.83 and 1.95 kilometers. The interpretation was supported by some limited deep borings in the area. The discovery of this deeper component of the aquifer demonstrates interpretations of these systems through traditional methods, such as correlating borehole information, can miss important features due to lack of spatially continuous information.
2020-12-01T00:00:00ZInvestigating the effects of weather, artificial lighting, and polarized light on bird-building collisions in the downtown area of a major U.S. CityLao, Sirenahttps://hdl.handle.net/11244/3396072023-09-22T05:04:10Z2019-05-01T00:00:00ZInvestigating the effects of weather, artificial lighting, and polarized light on bird-building collisions in the downtown area of a major U.S. City
Lao, Sirena
Collisions with buildings are a major source of human-caused mortality of birds, killing up to 1 billion birds annually in the United States. Most bird-building collision studies have focused on building and landscape-related factors that contribute to collisions, such as glass area and the amount of surrounding vegetation. Some studies have also considered characteristics of birds, such as migratory behavior and feeding habits, that cause some groups to be more vulnerable to collisions. Nocturnally migrating birds are especially susceptible to collisions, and the combination of poor weather conditions and artificial light at night (ALAN) is frequently cited as causing large collision events. However, little research has formally analyzed these factors. As part of a study evaluating collisions at 21 buildings in downtown Minneapolis, Minnesota, USA, we assessed the effects of nightly weather conditions on collisions across all study buildings. We also evaluated the relationship between collisions and two types of light pollution—ALAN and polarized light pollution (PLP), which has never been analyzed as a collision factor—at 48 façades of 13 buildings.; For weather, we found that favorable migration conditions (e.g., tailwinds) early in the night and poor weather conditions (e.g., low clouds) later in the night correlated with collisions. We also found that time lag effects (conditions from one and two additional nights before surveys) were especially important in the spring, while collisions were primarily associated with weather conditions from the night before surveys in the fall. These results provide support for using weather and bird migration forecasts to predict collisions, allowing advance action to be taken to reduce collisions.; For light pollution, we found that the area of windows emitting ALAN and the proportion of lighted glass were important factors influencing collisions, even after accounting for glass area. This result provides strong support for turning off lights at night to reduce bird-building collisions. We found no relationship between PLP and collisions, but additional research is needed to better understand bird responses to PLP. Nonetheless, reducing both types of light pollution by turning off lights and reducing reflective surfaces should contribute to significantly reducing bird-building collisions.
2019-05-01T00:00:00ZEquine infestation with common North American ticks: Diversity, seasonality, and attachment site preferencesSundstrom, Kellee Dawnhttps://hdl.handle.net/11244/3396052023-09-22T05:15:03Z2021-07-01T00:00:00ZEquine infestation with common North American ticks: Diversity, seasonality, and attachment site preferences
Sundstrom, Kellee Dawn
Ticks are common on horses, and the species and stages infesting horses have been documented in many regions of the world. However, recent publications characterizing equine tick infestations in North America are lacking, especially documentation of attachment site preferences and seasonality from the same geographic location throughout the year. To further understand attachment site preferences of common ticks of horses, and to document the seasonality of equine tick infestation in northeastern Oklahoma, horses from eight farms were evaluated twice a month over a one-year period. Each horse was systematically inspected beginning at the head and moving caudally to the tail. Attachment site of ticks was recorded and all ticks collected and identified to species and stage. A total of 2,731 ticks were collected; 84.1% (74/88) of the horses were infested (median=2 ticks) at one or more examinations. Five tick species were identified, including Amblyomma americanum (78.2%; 2,136/2,731), Ixodes scapularis (18.2%; 497/2,731), Dermacentor albipictus brown variant (2.6%; 71/2,731), D. variabilis (0.7%; 20/2,731), and A. maculatum (0.3%; 7/2,731). Most ticks were adults (83.6%; 2,282/2,731), but immature A. americanum (436/2,136; 20.4%), D. albipictus (12/71; 16.9%), and A. maculatum (n=1) were occasionally recovered. Amblyomma americanum were most often attached to the inguinal area, and I. scapularis and D. albipictus were most commonly found on the chest and axillary region (P < 0.0001). Ticks were found on horses in every month of the year. The largest number of ticks (638/2,731; 23.4%) were collected in May (P < 0.0001). Amblyomma americanum, primarily immature, was the only tick recovered in September, I. scapularis and D. albipictus predominated October through February, and both A. americanum and I. scapularis were common in March. In the warmer months, April through August, A. americanum was the most common tick, followed by D. variabilis and A. maculatum. This research confirms that ticks common on horses in North America have attachment site preferences, and that ticks infest horses in Oklahoma throughout the year, including during the winter. Additional research is warranted to fully understand the risk these infestations pose to equine health and to investigate an effective tick control for equids.
2021-07-01T00:00:00Z