229 research outputs found
Contrasting Influence of Natural Nighttime Illumination on Capture Rates of the American Burying Beetle and Roundneck Burying Beetle (Coleoptera: Silphidae)
No full textFig. 3. Seasonal dynamics of illumination of the moon (%) and raw trap counts for the A) Oklahoma and B) Nebraska data sets. Raw counts do not account for trap number, clouds, or other weather variables.Published as part of Wormington, Jillian D., Risser, Kyle, Hoback, W. Wyatt, Giles, Kristopher L., Greenwood, Carmen & Luttbeg, Barney, 2017, Contrasting Influence of Natural Nighttime Illumination on Capture Rates of the American Burying Beetle and Roundneck Burying Beetle (Coleoptera: Silphidae), pp. 339-347 in The Coleopterists Bulletin 71 (2) on page 346, DOI: 10.1649/0010-065X-71.2.339, http://zenodo.org/record/536395
Optimization of nitrogen fertilizer application enhances biocontrol function and net income
No full textThe intensive use of nitrogen fertilizer has been a common approach for pursuing higher crop yields. However, the ecological effects of such use on the tritrophic interactions (crop-insect pest-natural enemy) and on the ecological and economic benefits of such use are poorly understood. Here, we investigated the effects of low, medium, and high levels of nitrogen fertilizer inputs (70, 140, and 280 kg/ha/yr) on cereal aphid (Sitobion avenae Fabricius [Hemiptera: Aphididae], Schizaphis graminum Rondani [Hemiptera: Aphididae], and Rhopalosiphum padi L. [Hemiptera: Aphididae]) abundance, primary parasitism rates, crop yield, and net income in winter wheat (Triticum aestivum [Poales: Poaceae] cv. Zhou 22) for 2 yr. A higher input of nitrogen fertilizer significantly enhanced the abundance of cereal aphids, while their primary parasitism rates (26.9 ± 3.5% in 2018 and 24.9 ± 4.5% in 2019) were highest at the medium nitrogen level. The performance of participants in the wheat-aphids-parasitoids system was likewise mediated by the nitrogen fertilizers. Meanwhile, wheat yield significantly increased with moderate increases in the nitrogen level, although overuse of nitrogen fertilizer did not significantly further enhance wheat yield. Finally, we found either low or overuse of nitrogen fertilizers resulted in lower net income than did medium nitrogen fertilization. These results demonstrate the need to reevaluate and adjust fertilizer use to optimize the eco-economic and sustainable management of agroecosystems
Areawide Pest Management of Cereal Aphids in Dryland Wheat Systems of the Great Plains, USA
No full textIn the Great Plains of the USA from Wyoming to Texas, dryland winter wheat either is regularly grown continuously or is followed by a year of fallow in semi-arid locales (Royer and Krenzer, 2000). It has been well documented that these continuous monocultures can, over time, lead to increased levels of all types of pests (i.e. insects, diseases and weeds) (Andow, 1983, 1991; Vandermeer, 1989; Cook and Veseth, 1990; Elliott et al., 1998a; Way, 1998; Ahern and Brewer, 2002; Boyles et al., 2004; Brewer and Elliott, 2004; Men et al., 2004). Relative to insect pests, the ephemeral nature of insect host resources in these mono culture systems is assumed to curtail the efficiency of natural enemies, leading to increased pest pressure and reduced yields (Booij and Noorlander, 1992; Tscharntke et al., 2005; Clough et al., 2007).
From an ecological standpoint, the absence of habitats that support natural enemies in these monoculture agricultural systems are considered a primary reason why populations of aphids such as the greenbug (GB, Schizaphis graminum) and the Russian wheat aphid (RWA, Diuraphis noxia) increase above economic injury levels (EILs) (Elliott et al., 1998b, 2002a; French and Elliott, 1990a; Brewer et al., 2001; French et al., 2001a; Giles et al., 2003; Brewer and Elliott, 2004). Economic losses associated with both GB and RWA average US$150 million annually across the Great Plains of the USA (Webster, 1995; Morrison and Pears, 1998)
Evaluating How Wetland Presence and Restoration Effects Landscape and Resource Use of Pollinator Communities in an Agricultural Matrix
No full textPollination is critical for ensuring biodiversity and human food supplies. However, wild pollinator populations are declining due to fragmentation and loss of habitat. These concerns are apparent in the Rainwater Basin of Nebraska, where more than 90% of the region has been cultivated. The small number of playa wetlands and their adjacent uplands present in this region are the only natural habitat available for pollinators. My objective was to document wild pollinating insects in south-central Nebraska and observe how they utilize the landscape for habitat and food resources. I used blue vane traps to passively collect insects and insect nets to obtain actual habitat and foraging information from April through October in 2014 and 2015. I compared pollinator abundance, richness, and diversity by insect order in wetlands and uplands within three land uses: cropland, reference condition, and restored sites implemented through the Wetlands Reserve Program. Net data for dominant pollinating families were analyzed using a Principle Response Curve to observe the effects of land use, watershed position, and dominant food plant on foraging habits. Additionally, vegetation data were collected using the step-point intercept method to determine differences in plant community among land uses. Dominant plant species were analyzed using a Partial Canonical Correspondence Analysis.Numerous insect orders were collected, but bees were dominant. Trap data showed bees used restored and reference uplands over wetlands and croplands, most likely due to nesting resources only being available in watershed grasslands. Net collections showed bees foraged more in wetlands than uplands, especially in wetlands that have undergone restoration. However, in September, bees foraged in uplands and crop wetlands more than restored or reference wetlands in order to feed on late season forbs. Apidae exhibited strong associations with smartweeds and goldenrods in late summer, neither of which were associated with restored sites. To ensure viable pollinator communities throughout the growing season, restoration practices should provide more diverse wetland flora and additional late season upland forbs than is being currently provided. Additional pollinating orders discussed include Diptera, Coleoptera, and Lepidoptera.Zoolog
I Went to the End of Time, and This is What I Found: A Look into the Making of a Solo Performance
No full textabstract: I'll go to the end of time for you (and you don't even know my name) is an evening-length solo performance created and performed by Kristopher K.Q. Pourzal. It premiered November 8-10, 2013 in the Margaret Gisolo Dance Theatre of Arizona State University. The solo was the culmination (suspension, really) of a wild creative journey, the distillation of a process that initially involved several collaborators. Through a series of neurotically/erotically repetitive episodes of self-composed song, text, and dance, the work mines questions of the desire to be seen and the desire to feel alive. The conventions and constructs of the proscenium stage are both utilized and subverted in examining this platform as uniquely suited for revealing the nature of these experiences and their potential relationship. This document is primarily an account of the show's process--its before and after--and serves as a site of exploration, explanation, analysis, reflection, questioning, and ultimately furtherance of the practice-based research made manifest in the performances.Dissertation/ThesisM.F.A. Dance 201
Ultrafast extreme ultraviolet spectroscopy of transition metal dithiolate coordination complexes
No full textTransient tabletop M-edge x-ray absorption near edge structure (XANES) spectroscopy using extreme ultraviolet (XUV) light is used as a tool to interrogate the evolution of the metal center in a series of transition metal dithiolate complexes. The behavior of these molecules after absorption of light has implications for the development of catalysts and photosensitizers using earth-abundant transition metals. The cobalt dithiolene complex, [Co(bdt)2]- (bdt = 1,2-benzendithiolate), is primarily known for its ligand-noninnocence and participation in the catalytic production of hydrogen. After excitation of [Co(bdt)2]- with visible light, its relaxation dynamics are tracked with a combination of optical and transient M-edge XANES spectroscopic techniques that allow for the identification of a ligand-to-metal charge transfer (LMCT) excited state whose spin can be determined by comparison to semi-empirical ligand field multiplet calculations. The combination of optical and x-ray techniques is crucial to identifying relaxation processes that affect predominantly either the metal or the ligand. NEVPT2 calculations are used to understand its optical absorption spectrum and rationalize the timescale by which the molecule relaxes to the ground state. A set of three of cobalt tris(dithiolate) complexes with varying ligand field strength have been studied using optical transient absorption spectroscopy which shows a difference of a factor of at least ten in their excited state lifetimes. Understanding the origin of this change is important to further extending the lifetimes of photosensitizers. The sensitivity of M-edge XANES spectroscopy to the oxidation and spin state of a metal enabled the identification of the excited states involved in the relaxation of all three complexes. The contribution of a long-lived charge transfer state was ruled out and the final excited state was determined to be a 5T state. Finally, a nickel dithiocarbamate complex, Ni(dedtc)2 (dedtc = diethyldithiocarbamate, S2CNEt2) was studied as a simple analogue of a square planar nickel-centered hydrogen catalyst. Examination of this complex and the equivalent copper and zinc complexes reveal new phenomena in XUV spectroscopy, including dependence of the ligand absorbance on the metal center and observation of a ligand-based change in absorbance beneath the nickel M-edge after LMCT excitation.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-05-01The student, Kristopher Benke, accepted the attached license on 2021-04-12 at 10:11.The student, Kristopher Benke, submitted this Dissertation for approval on 2021-04-12 at 10:46.This Dissertation was approved for publication on 2021-04-14 at 11:42.DSpace SAF Submission Ingestion Package generated from Vireo submission #16283 on 2021-09-16 at 17:02:51Made available in DSpace on 2021-09-17T02:34:23Z (GMT). No. of bitstreams: 3
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Optimizing biotic mortality for management of the alfalfa weevil Hypera postica Gyllenhal (Coleoptera: Curculionidae)
No full textDespite the regulatory importance of H. postica natural enemies, relatively few efforts have been made to integrate natural enemies and management tactics into holistic management programs. This is primarily due to the lack of quantitative information on the interactions between H. postica natural enemies and management tactics. The objectives of this study were to (1) initiate local epizootics of the fungal entomopathogen Zoophthora phytonomi Arthur (Zygomycetes: Entomophthoraceae) through inoculative host releases; (2) quantify the effects of reduced insecticide rates, or strip harvesting, on H. postica larval populations and transmission of Z. phytonomi; (3) determine the effects of reduced insecticide rates, or strip harvesting, on the larval parasitoids Bathyplectes curculionis Thomson (Hymenoptera: Ichneumonidae) and B. anurus; and (4) determine the effects of reduced insecticide rates, or strip harvesting, on selected arthropod predators. These studies provide a basis for the development of a holistic integrated pest management program for H. postica. We have demonstrated that: (1) transmission and development of Z. phytonomi occurs in H. postica larvae exposed to low rates of Lorsban 4E°ler (chlorpyrofos); (2) combined mortality between reduced rates of insecticide and Z. phytonomi is additive in alfalfa fields when timed with the development of Z. phytonomi; and (3) high levels of H. postica mortality can be achieved while conserving larval parasitoid species and arthropod predator abundance through the use of reduced rates of insecticides applied in selected areas of an alfalfa field.</p
Ecological Studies of the Psocid Liposcelis rufa Broadhead (Psocoptera: Liposcelididae)
No full textPsocids (Psocoptera) have risen to prominence as serious pests of stored-products worldwide in the last two decades. However, very little is known about their ecology and biology which is crucial for the development of effective management strategies. In this study, I investigated the effects of constant temperatures and relative humidities on the population growth, effect of constant temperatures at optimal relative humidity on the development and reproductive parameters of Liposcelis rufa in order to elucidate the influence of environmental conditions on its biology and the ecology. My research has shown that L. rufa can survive and multiply at a low relative humidity of 55% at temperatures of 22.5 to 30C and a high temperature of 40.0C at 75% RH. The optimal conditions for reproduction for this species are 35.0C and 75% RH where population increased 73- fold. The shortest developmental time from egg to adult was recorded at 37.5C; at this temperature development of female was completed in 21.6 d. Males have shorter life cycle than females and this may be due to the fact that females have one more instar compared to males. L. rufa males had two to four instars whereas females had two to five instars. Temperature has significant effect on development time for all developmental stages. Also, my work has demonstrated that L. rufa has a higher intrinsic rate of population increase compared to other psocid species (0.18). It oviposits at a wider range of temperature from 25 to 40C, and the highest fecundity was recorded at 30C (63 eggs).The highest oviposition rate was recorded at 35C (15.4 eggs/ female/ wk), 2 wk after the initiation of oviposition. L. rufa can live up to 9 wk at 40C, and the longest living individual lived 219 d at 27.5C. Given its ability to multiply rapidly at high temperatures and relative humidities, its short life cycle, high intrinsic rate of increase, and the ability to live for long, especially at higher temperatures suggests L. rufa has great potential to be a serious stored product pest in hot and humid climates. In addition, it is likely to have a broader ecological distribution because it can survive and multiply at temperatures of 22.5 - 40C and 55-75% RH. Finally, the temperature-dependent equations I have developed for L. rufa developmental stages and reproductive parameters can be used to elucidate its population dynamics and to facilitate the development of effective management strategies for this pest.Department of Entomology and Plant Patholog
Genetic Variation Within and Between Russian wheat aphid, Diuraphis noxia (Kurdjumov), Biotypes Found in the United States
No full textThe Russian wheat aphid, Diuraphis noxia (Kurdjumov), is a pest on wheat and barley in the Western United States. Management is achieved primarily by resistant varieties. In 2003, the Russian wheat aphid caused damage to wheat with the Dn4 resistance gene in Southeastern Colorado. The damaging biotype was designated RWA-2 and the extant population RWA-1. Plant response experiments showed variation within RWA-2 clones based on chlorosis, plant height, and shoot dry weight to wheat with the Dn4 resistance gene. Phenotypic variation found within RWA-2 argues against the hypothesis that RWA-2 populations consist of a single, genetically identical clone. I conducted studies to observe variation between and within Russian wheat aphid biotypes using 12 clones of RWA-1 and RWA-2 biotype, and a single clone of: RWA-3; RWA-4; and RWA-5 biotypes, determined according to plant response to Dn genes. Using RAPD-PCR, three single band polymorphisms were detected distinguishing RWA-5 and clone 7 (RWA-2) after screening all Russian wheat aphids with 58 primers. I found no sequence variation within or between biotypes in a 436 bp fragment of the COI gene in the mtDNA. Seven microsatellite DNA markers were used to evaluate clonal diversity, but no variation was found. In addition, cuticular hydrocarbon analysis was performed on multiple aphids belonging to a single clone of RWA-1, RWA-2, RWA-3, RWA-4, and RWA-5. This method showed RWA-1 and RWA-2 had unique hydrocarbon mixtures, based on principal component analysis. Ultimately all five biotypes could be separated according to canonical variables. Using genotypic markers, Russian wheat aphid biotypes are homogenous, and consist of a single introduction into the United States. Using phenotypic markers, RWA-1 and RWA-2 are more distinctive of the five Russian wheat aphid biotypes. Lack of genotypic variation could have resulted from a founder effect upon introduction into North America, followed by bottlenecking of populations in the United States.Department of Entomology and Plant Patholog
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