This research was conducted to quantify short- and long-term effects of atmospheric carbon dioxide on wheat. Growth, development, and yield of the spring wheat cultivar Veery-10 were measured in response to CO2 concentrations of 340 (ambient), 1200, and 2500 μmol moI-1 of CO2 air. These 3 CO2 levels were chosen to provide a control group, a predicted optimal CO2 environment, and a potentially toxic CO2 environment, respectively. A recirculating hydroponic system provided a near-optimal root-zone environment that was identical for all CO2 treatment levels. Environmental factors, other than CO2, were controlled at near optimal levels, although photosynthetic photon flux was actually suboptimal and higher levels would increase growth. Standard growth analysis procedures were used to measure growth rates and carbon partitioning to leaves, stems, and roots. Yield components were measured on mature plants. Because elevated CO2 levels may increase growth by increasing radiation absorption or by increasing photosynthetic efficiency, measurements of absorbed photosynthetic photon flux were calculated from measurements of incident, reflected, and transmitted photosynthetic photon flux. Growth and yield were increased by the 1200 μmol moI-1 of CO2 in air treatment in all trials. Growth and yield were reduced by the 2500 μmol moI-1 treatment in both long-term trials, but growth was not reduced by this treatment in two short-term trials. These data indicate that CO2 is toxic to wheat at 2500 μmol moI-1 (0.25%), but the effects are not expressed until the last half of the life cycle.

Leptinotarsa decemlineata (Say) is the most important defoliating pest of potato Solanum tuberosum L., in North America and Europe.  Management of this pest relies heavily on chemical control and insecticide resistance is a persistent problem.  This phenomenon has increased the need for developing novel insecticides, resistance evaluation, and the development of alternative control strategies regarding this insect pest.  From 2010 to 2013, field and lab experiments were conducted to evaluate the efficacy of a novel insecticide tolfenpyrad on L. decemlineata.  In leaf-dip assays, tolfenpyrad was highly toxic to L. decemlineata with LC50 values of 0.013 and 0.164 g ai/L for larvae and adults, respectively.  Tolfenpyrad was also toxic to eggs with 0% hatching after being dipped in a field rate concentration.  In field efficacy trials, potato plots treated with tolfenpyrad at rates as low as 153 g ai/ha effectively controlled L. decemlineata. In 2012, populations of L. decemlineata were collected from the Eastern Shore of VA and subjected to toxicity assays to determine current susceptibility to permethrin and oxamyl.  The toxicity assays indicated an increase in toxicity to permethrin in L. decemlineata larvae (LC50 = 3.931 g ai/L) and an increase in toxicity to oxamyl in adult beetles (LC50 = 9.695 g ai/L) compared with LC50 values previously reported in 1990.  In 2012, populations of L. decemlineata from Cheriton, VA, New Church, VA, Painter, VA, and Plymouth, NC were also evaluated for enzyme activity after exposure to sub-lethal concentrations of permethrin, oxamyl, and tolfenpyrad.  Adult beetles were subjected to enzyme assays to measure the activity of cytochrome P450 mono-oxygenase (P450), glutathione-S-transferase (GST), general esterases, and protein content.  Results from the enzyme assays indicated significantly greater esterase activity in beetles from Painter, VA exposed to permethrin [±-naphthol (F= 11.66, df= 4, 20, P<0.0001) and "-naphthol (F= 11.86, df= 4, 20, P<0.0001)], oxamyl [±- naphthol (F= 10.64, df= 4, 20, P<0.0001) and "-naphthol (F= 6.94, df= 4, 20, P=0.0011)], tolfenpyrad [±- naphthol (F= 407.62, df= 1, 8, P<0.0001) and "- naphthol (F= 28.15, df= 1, 8, P= 0.0007)], and the untreated control [±- naphthol (F= 28.14, df= 3, 16, P<0.0001) and "- naphthol (F= 28.86; df= 3, 16, P<0.0001)] compared to most of the other populations tested.  GST activity was significantly greater in tolfenpyrad exposed beetles compared to the non-treated beetles from Painter VA (F= 17.66, df= 5, 24, P< 0.0001). Through laboratory assays and field experiments in potato, the efficacy of a new bio-pesticide derived from the bacterium Chromobacterium subtsugae was evaluated for the control of L. decemlineata.  Results from the laboratory assays showed L. decemlineata feeding was inhibited by the bio-pesticide derived from C. subtsugae.  However, field efficacy trials in 2010, 2011, and 2012, indicated no control of L. decemlineata. Methyl salicylate is an organic compound produced by potato and other plants in response to insect herbivory.  Abundance of predatory arthropods and L. decemlineata life stages were measured in plots treated with and without 5 g slow-release packets of methyl salicylate (95% methyl salicylate (Predalure")).  Methyl salicylate treatment had no impact on predator recruitment or cumulative mortality of L. decemlineata in potatoes. This research has provided us with a new tool for L. decemlineata management, as well as more information about resistance trends and alternative control strategies from which we can build on to reduce resistance development in L. decemlineata and ultimately formulate a stronger integrated pest management strategy for this insect pest. / Ph. D.

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No description available.

No description available.

Because endorphin receptor activation alters the function of the central noradrenergic system, opiates may change the regenerative sprouting of neurons in response to adrenergic neurotoxins. To test this hypothesis, newborn rats were treated with several opioids and 6-hydroxydopa (6-OHDOPA) and the development of the noradrenergic system was evaluated. In combination with 6-OHDOPA morphine and naloxone potentiated the development of norepinephrine (NE) levels in the pons-medulla and cerebellum by four weeks of age. β-Endorphin, Leu- and Met-enkephalin and d-Ala2-enkephalinamide produced a similar effect in the pons-medulla. The effect of morphine was partially attenuated by naloxone. Increased cerebellar noradrenergic histofluorescent staining was observed with the morphine + 6-OHDOPA and naloxone + 6-OHDOPA treatments. Both naloxone and morphine decreased NE levels in the pons-medulla of adult rats treated with 6-OHDOPA. These results suggest that opiates and endorphins may enhance sprouting of noradrenergic neurons following neonatal treatment with 6-OHDOPA, by increasing the toxicity of this neurotoxin.

Stormwater runoff can be a great concern in the State of Florida due to the impact the quality of the runoff water can have on the natural water bodies. Stormwater runoff can carry pollutants and sediments which can cause both physical and biological risks in an aquatic ecosystem such as a lake, river, or pond. Polymers, namely the chitosan-based dual polymer system, can be used remove the sediment from this runoff to ensure the safety of the state’s water bodies. Three soils are used in this testing: AASTO soil classifications A-3(sandy soil) and A-2- 4 (silty-sand), and a soil with a fine-grained limerock component. An optimum dose of the chitosan-based dual polymer system is first determined using jar testing. The optimum dose is the dose that reduces the final turbidity to 29 NTUS or below and creates significant flocs. The under dose and over dose are calculated based on the optimum dose. Using these dosages, field scale tests are conducted using two different treatment methods: a semi-passive treatment method and a passive treatment method. Whole effluent toxicity and residual chitosan tests are then conducted on the effluent from the field scale treatment methods. The passive treatment method is the best field scale treatment method when using the silty-sand and the soil with a fine-grained limerock component. The semi-passive treatment method is the best field scale treatment method when using the sandy soil. The passive treatment method with the silty-sand achieves a final turbidity of 123.9 NTUS (88.45% removal). The passive treatment method with the soil with a fine-grained limerock component achieves a final turbidity of 132 NTUS (83.86% removal). The semi-passive treatment method with the sandy soil achieves a final turbidity of 31.43 NTUS (82.04% removal). There is only significant toxicity associated with the tests using iv the effluent from the passive treatment method with the soil with a fine-grained limerock component which only uses the cationic polymer

Used tires have the potential for becoming popular in pollution control media used in stormwater applications including pervious pavement sub bases, green roof growth media, and upflow filters. Using tire crumb to decrease nutrients can minimize impacts on ecology while reducing the human footprint left by used tires. However, if tire crumb is not examined for toxicity, the ecological balance could unknowingly be disrupted. This research tested the acute toxicity of tire crumb in aquatic systems by finding the Lethal Concentration for 50% kill (LC50). Using an extreme tire crumb load, P. promelas (fathead minnow) were exposed to leachates created with tire crumb and several different types of water including distilled water, tap water, and detention pond water. For distilled and tap water, the addition of tire crumb increased the survival of P. promelas. For detention pond water, the addition of tire crumb decreased the survival of P. promelas, though only enough to find an LC50 for detention pond water influenced immediately by stormwater runoff. An LC50 was found when 100 percent tire crumb filtrate is prepared with 25 grams of tire crumb per liter of detention pond water collected directly after a storm. The LC50 found is resultant of a tire crumb load significantly higher than what can be expected in the environment. Based on this research, tire crumb is considered non-threatening to aquatic fish and safe to use with detention pond water.

Ammonia is known to be toxic to aquatic organisms. The national water quality criteria for ammonia in the marine environment have been established to protect aquatic organisms from the toxicity of ammonia. Discharge into Chesapeake Bay has not yet been regulated under this criteria. Ammonia limits of 1-2 mg/L total ammonia have been proposed for the marine waters in Virginia based on the national criteria of 0.035 mg/L of un-ionized ammonia. The limits have been questioned because the criteria were calculated using toxicity data from both freshwater and saltwater species, rather than solely from saltwater species. More ammonia toxicity tests need to be conducted to expand the database with saltwater species in order to develop a reliable and appropriate limits for ammonia discharge. Two saltwater species, one marine fish, Atlantic silverside (Menidia menidia), and one marine invertebrate, ghost shrimp (Palaemonetes pugio), were tested in acute and 7-day chronic tests. The acute tests for the Atlantic silverside were performed at three levels of salinity in order to develop a better understanding of the relationship between ammonia toxicity and salinity levels. The acute LC50values for both species were determined and compared to values in the literature. The 48-hour LC50 values for the Atlantic silverside were 1.50, 1.17, and 1.08 NH3 mg/L at salinities of 14, 22, and 30 ppth, respectively. The 96-hour LC50 for the ghost shrimp was 1.66 NH3 mg/L. The species mean acute values (SMAVs) for the Atlantic silverside (2% difference) and the ghost shrimp (31% difference) were compared to previous test results. The no-observed-effect-concentration (NOEC) was 0.48 NH3 mg/L for the Atlantic silverside based on growth, and 0.33 NH3 mg/L for the ghost shrimp based upon growth. The acute-chronic ratio for the ghost shrimp was 7.56. The refined national chronic criterion of un-ionized ammonia was 0.056 mg/L according to the test data from this research. / Master of Science

The discharge of wastewaters containing ammonia has become a major environmental concern, especially in the Chesapeake Bay watershed. A tentative instream limit of 1-2 mglL for total ammonia has been proposed in Virginia to protect marine aquatic life. This limit was based upon the national chronic criterion for un-ionized ammonia (0.035 mg/L) which was calculated using both freshwater and saltwater toxicity data. Therefore, additional bioassays needed to be performed with marine organisms in order to refine this limit based solely on saltwater organisms. Acute bioassays were conducted with one marine fish, the sheepshead minnow (Cyprinodon variegatus), and two marine invertebrates, the mysid (Mysidopsis bahia), and grass shrimp (Palaemonetes pugio). The acute LC 50 and the no-observed-effect-concentration (NOEC) were determined for each organism and compared to data in the literature. The species mean acute values (SMA V) for the sheepshead minnow (13.5% difference) and the mysid (14.7% difference) compared well with the literature, while the grass shrimp was more tolerant (81.2% difference) to ammonia than expected. The SMA V were calculated based upon the LC 50 data and used to assess both the national acute and chronic criterion for ammonia. Seven day chronic bioassays were performed with the sheep shead minnow (Cyprinodon variegatus). The LC 50 and the NOEC for both mortality and growth were calculated. The acute-chronic ratio was determined to be 6.95 for the sheepshead minnow and 4.35 for the mysid. Based upon these data, the refined national criteria for unionized ammonia was determined to be 0.054 mg/L. The instream limit can be set based upon the water pH, temperature, and salinity. / Master of Science