Browsing by Author "Kondratieff, Boris C., committee member"
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- ItemOpen AccessDDT and pyrethroid resistance in Xenopsylla cheopis (Rothschild), the Oriental rat flea in northern Uganda(Colorado State University. Libraries, 2011) Ames, Abbe D., author; Black, William C., IV, advisor; Gage, Kenneth L., advisor; McAllister, Janet C., committee member; Kondratieff, Boris C., committee member; Cole, Patricia A., committee memberDevelopment of insecticide resistance by vectors of disease is a well-recognized and continuous concern for public health officials. Monitoring insects for development of resistance to the chosen toxicants is part of effective management philosophy. Several programs to control mosquito vectors of malaria utilize insecticides with similar modes of action targeting the insect. Fleas can vector plague and in many areas inhabit the same environment that is the focus of mosquito management. Non-target insect development of resistance is a phenomenon most commonly associated with agriculture, but can also apply to insect vectors that threaten public health. Rapid and effective methods of monitoring for the possible development of insecticide resistance in fleas are important measures taken to prevent or suppress a plague outbreak. This study describes the development and application of a new field assay for evaluating phenotypic demonstration of insecticide resistance in fleas, results of biochemical analyses performed to evaluate possible development of metabolic detoxification pathways, and the subsequent elucidation of the para voltage gated sodium channel gene in Xenopsylla cheopis (Rothschild) with concurrent analyses of the prevalence and effects of knockdown (kdr) mutations in the gene. The field assay used a glass Petri dish coated with a dose of a chosen insecticide and a time mortality assay that was performed for 60 minutes. Discriminating concentrations, established on colony reared fleas, was tested on field collected fleas in northern Uganda. Fleas from villages with a history of indoor residual spraying (IRS) of DDT and /or pyrethroid were tested with those insecticides and significant increased survival was demonstrated. Phenotypic resistance to DDT was demonstrated with an 81.8% survivorship. Lambda-cyhalothrin tested fleas from three villages demonstrated phenotypic resistance of levels of 57.7%, 60.5%, and 58% survivorship. Enzyme profiles indicated increased levels of expression of α-esterase and β-esterase in field caught fleas compared to colony-reared fleas. Fleas potentially exposed to DDT and/or pyrethroids had higher levels than did unexposed fleas. An increase in insensitive acetylcholinesterase was found in fleas from villages with no known history of IRS. No increase in glutathione S-transferase was noted in any population. The para voltage gated sodium channel gene for X. cheopis was amplified and sequences for colony and Ugandan fleas were analyzed with emphasis on knockdown resistance (kdr) evolution in the fleas. Extensive evidences of selective pressures influencing genetic profiles of kdr development faster than expected for random mutation or recombination were found. The phenylalanine allele, associated with kdr, was found at an average of 95.1% frequency in villages with an IRS history. Field caught fleas with no known insecticide exposure had an allele frequency of 13.3%. All three studies clearly indicate resistance is developing quickly in Ugandan flea populations and should be addressed with surveillance and management.
- ItemOpen AccessEvaluating the direct and indirect effects of acid mine drainage on stream ecosystems using field and novel experimental approaches(Colorado State University. Libraries, 2019) Kotalik, Christopher J., author; Clements, William H., advisor; Kondratieff, Boris C., committee member; Winkelman, Dana L., committee member; Meyer, Joseph S., committee memberTo view the abstract, please see the full text of the document.
- ItemOpen AccessInfluence of abiotic and biotic factors on the response of benthic macroinvertebrates to metals(Colorado State University. Libraries, 1995) Kiffney, Peter Michael, author; Clements, Will, advisor; Fausch, Kurt D., committee member; Kondratieff, Boris C., committee member; Chapman, Phillip, committee memberStream ecologists are well aware that chemical, biological, and physical characteristics of lotic systems vary spatially and temporally. With this in mind, I designed a series of experiments and field studies to examine the role of spatial variation in stream benthic macroinvertebrate communities in response to metals. Specifically, I tested the hypothesis that stream invertebrate communities from pristine streams of different size and altitude varied in their response to metals. To evaluate how metals affected biotic interactions, I manipulated invertebrate density, predation intensity, and metals in stream microcosms. Using stream invertebrate communities, I also designed an experiment and field survey to identify reliable bioindicators of metal contamination in western streams. Results from microcosm experiments and field studies showed that benthic invertebrate populations from high-altitude streams were more sensitive to the effects of metals than invertebrate populations from low-altitude streams. For example, Baetis sp. and Rhithrogena hageni from Little Beaver Creek (LBC), Colorado, (high-altitude stream) were significantly more sensitive to zinc than the same species from the South Fork of the Poudre River (SFP) (low-altitude stream) in stream microcosms. Results from field surveys showed that densities of most groups of aquatic insects (e.g., Ephemeroptera, Plecoptera, Trichoptera) were lower at high-altitude metal contaminated streams than those same groups at low-altitude streams. Other factors, such as variation in water temperature or nutrient concentrations between high- and low-altitude streams, could be lll responsible for these differences. However, because invertebrate responses were similar under controlled and field conditions, I hypothesize that differences in abundances between reference and contaminated locations was a result of metals. To determine if body size contributed to the variation in sensitivity of insects to metals, size measurements were made on species collected from LBC (high-altitude) and SFP (low-altitude). Measurements were also made on species from control and metal-treated stream microcosm. Most species were smaller at LBC (high-altitude stream) than the same species from SFP (low-altitude stream). For example, the mayfly Baetis tricaudatus and the caddisfly Arctopsyche grandis were significantly larger at SFP than LBC. In addition, insect body size was larger in metal-dosed microcosms than in controls. Brachycentrus sp., B. tricaudatus, R. hageni, Eohemerella infrequens, and P. badia were significantly larger in metal-treated microcosms than in controls. Logistic regression indicated survival in metal-dosed microcosms was less for small individuals than for larger individuals of the same species. These results suggest that some insect species from high-altitude streams were smaller than those from low-altitude streams, and that survival was greater for larger lifestages. Thus the variation in response of macroinvertebrates between different altitude streams observed in earlier studies may be due to differences in body size. The effects of low levels of metals (half the chronic levels of Cd, Cu, and Zn) on some species varied in relation to invertebrate density (low and high density) and invertebrate predation (no predators added and predators added). The abundance of Hydropsyche sp. was significantly lower in metal-dosed, high density treatments than in control, high density treatments. Moreover, the effects of an invertebrate predator (Hesperoperla pacifica) on Hydropsyche sp. was significantly greater in metal-dosed microcosms than in controls. These results suggest that metals interact with biotic factors to influence stream invertebrate community structure, and that effects occurred at metal concentrations lower than chronic criteria value. Toxicity experiments in stream microcosms showed that the abundance and species richness of aquatic insects were significantly reduced at 1x, 5x and 10x the United States Environmental Protection Agency chronic levels of cadmium, copper, and zinc (1x=1.1, 5.0, and 110 μg/L Cd, Cu, and Zn, respectively). Mayflies were the most sensitive group, as the abundance of Baetis sp. and Rithrogena hageni were significantly reduced in the Ix treatment. The response of Drunella grandis was size dependent, as small lifestages were significantly more sensitive than large lifestages. Stoneflies were also affected, but their response was more variable with abundances of some species (Pteronarcella badia) being reduced in the Ix treatment, whereas other species were unaffected (Sweltsa sp.). Heptageniid mayflies were consistently less abundant downstream of sources of metal contamination in the Arkansas and Eagle rivers, whereas the response of other measures were more variable. For instance, species richness and total density were greater at a metal-contaminated site on the Arkansas River compared with an upstream reference site. Therefore, results from this experiment and field survey suggest that changes in abundance of heptageniid mayflies may provide a reliable indicator of metal-contamination in western streams.
- ItemOpen AccessIntegrated pest management of tomato/potato psyllid, Paratrioza cockerelli (SULC) (Homoptera: Psyllidae) with emphasis on its importance in greenhouse grown tomatoes(Colorado State University. Libraries, 1999) Al-Jabr, Ahmed Mohammad, author; Cranshaw, Whitney S., advisor; Bojstad, Louis B., committee member; Kondratieff, Boris C., committee member; Moore, Frank D., committee memberThe tomato (potato) psyllid, Paratrioza cockerelli (Sulc), has developed into a key insect pest of greenhouse tomatoes of western North America and few options have been available for its management. A series of trials were thus conducted to identify techniques that could be used in establishing an integrated pest management (IPM) program for the insect. In studies investigating improvements in sampling methods for tomato psyllid, the effects of trap color, trap orientation and height in respect to the crop were evaluated. Greatest captures of adult psyllids occurred on neon-green, neon-orange and standard yellow colored traps. Traps hung near the top of tomato plants captured significantly more psyllids than traps placed near the base of plants. Traps that were shaded or not orientated to receive direct sunlight caught fewer adult psyllids than did sun-exposed traps. Screening of potential psyllid control products emphasized those that were efficacious but also compatible with other insects used in greenhouse tomato production (e.g., parasitoids for whitefly control, pollinators). Tested materials included insecticides of microbial origin (Beauveria bassiana, Verticillium lecanii, Metarhizium anisopliae), microbial-derived insecticides (spinosad), selective synthetic insecticides (acetamiprid, pymetrozine) and selective botanical products (neem) for tomato psyllid control. The capability of B. bassiana to infect tomato psyllid and produce high mortality is reported for the first time. Acetamiprid, spinosad and formulations of Beauveria bassiana were particularly effective for control of tomato psyllid, consistently providing in excess of 80 percent control. As the latter two also are reportedly compatible with beneficial insects used in greenhouse tomato production they appear to show greatest potential for use in an integrated pest management program on the crop. Also, in trials of various repellents (Azatin XL, Trilogy, SunSpray and Garlic Barrier) for deterring oviposition, SunSpray and Trilogy did result in significant reductions in oviposition on treated leaves. Two species of green lacewings, Chrysoperla carnea Stephens and C. rufilabris (Burmeister) were evaluated for potential use as biological controls of tomato psyllid. Both species were capable of completing their life cycle on tomato psyllid. Chrysoperla carnea larvae consumed approximately twice as many psyllids as did C. rufilabris, but development of the latter was 50% faster (8 days vs. 12 days). An outdoor field trial involving applications of C. carnea eggs to psyllid-infested potatoes did not produce reductions in psyllid numbers. As soil applications of imidacloprid had previously been found to be highly effective for tomato psyllid, and had registration for use on field grown tomatoes, investigations were conducted on possible non-target effects on pollinators, specifically the bumble bee Bombus terricola occidentalis (Greene). Indications of adverse effects from imidacloprid were observed during these trials, including reduced activity of bees within the hive, reduced visitation to flowers, and often, reduced survival.
- ItemOpen AccessLandscape heterogeneity at multiple scales: effects on movement patterns and habitat selection of eleodid beetles(Colorado State University. Libraries, 1998) McIntyre, Nancy E., author; Wiens, John A., advisor; Wilson, Thomas (Tom) G., committee member; Kondratieff, Boris C., committee member; Hobbs, Nicholas Thompson (Tom), committee memberI combined observational studies with field experiments to investigate how landscape heterogeneity influences habitat selection in eleodid beetles of the shortgrass prairie of Colorado. I examined correlations in spatio-temporal patterns of habitat occupancy, population density, and community structure in eleodids with spatial and abiotic features of the landscape; I then explored how variations in spatial structure could affect how animals move through a landscape, accounting for the observed patterns of habitat occupancy. I combined these observations with experimental manipulations of several landscape features that affect the movement behaviors of beetles. The results from these experiments show how interactions among animal behavior, landscape composition and configuration, and the scale of spatial structure determine where animals occur in a heterogeneous environment.
- ItemOpen AccessMacroinvertebrate and microbial community responses to metal stress as measures of ecological recovery of a restored headwater stream(Colorado State University. Libraries, 2020) Wolff, Brian A., author; Clements, William H., advisor; Hall, Edward K., advisor; Kondratieff, Boris C., committee member; Schmidt, Travis S., committee memberTo view the abstract, please see the full text of the document.
- ItemOpen AccessNot all questions fit in beakers - direct and indirect toxic effects of metal mixtures and the application of ecotoxicological experiments to derive better water quality standards and predict recovery after abandoned mine reclamation(Colorado State University. Libraries, 2019) Cadmus, Peter, author; Clements, William H., advisor; Kondratieff, Boris C., committee member; Winkelman, Dana L., committee member; Ranville, James F., committee memberAqueous discharges from abandoned metal mines include complex mixtures of physical and chemical stressors. Consequently, identifying mechanisms and causal relationships between acid mine drainage (AMD) and community responses in the field is challenging. In addition to the direct toxicological effects associated with elevated concentrations of metals and reduced pH, mining activities influence aquatic organisms indirectly through physical alterations of habitat, including increased sedimentation, turbidity and substrate embeddedness. Although direct toxicity can sometimes be effectively studied in the laboratory, the indirect toxicity of toxicants rarely manifests into a measurable endpoint in the short duration and limited ecological realism of traditional laboratory toxicity experiments. The installation of a mine effluent treatment plant near Blackhawk Colorado (USA), had potential to remove the majority of aqueous metals from a mountain stream heavily degraded by Acid Mine Drainage (AMD). To investigate direct and indirect effects of Acid Mine Drainage (AMD) a series of field biomonitoring, field experiments, and mesocosm experiments were conducted. These studies quantified the relative importance of chemical (direct) and physical (indirect) stressors associated with AMD discharges and predicted recovery potential for dominant macroinvertebrate taxa. Ferric Fe is often a dominant toxicant present in AMD but is largely believed to be non-toxic to aquatic life. Results of toxicity tests reported here suggest that the current USEPA chronic Fe criterion is underprotective and that the current criterion should be reduced to 25% of its current level (251 µg/L). These studies demonstrated additional risk to aquatic insects and periphyton in metal mixtures that included ferric Fe. Responses were primarily a result of indirect physical effects associated with Fe oxide deposition rather than direct toxicity. All aquatic insects hatch as nearly microscopic organisms and small size classes were consistently the most sensitive in numerous experiments. Sampling small age classes in nature and conducting toxicity trials with small age classes is difficult and therefore these studies are lacking from the scientific literature. Failure to characterize sensitivity of early size classes may lead to gross overestimation of tolerance. Mesocosm experiments conducted using natural benthic communities provide a unique opportunity to quantify the relative importance of these indirect physical effects.
- ItemOpen AccessPhylogeography and character congruence within the Hoplias malabaricus Bloch, 1794 (Erythrinidae, Characiformes, Ostariophysi) species complex(Colorado State University. Libraries, 1996) Dergam, Jorge A., author; Behnke, Robert, advisor; Black, William C., IV, committee member; Kondratieff, Boris C., committee member; Fausch, Kurt D., committee member; Stack, Stephen, committee member
- ItemOpen AccessSoil mite biodiversity: its relationship to grass species and influence on decomposition in the Konza tallgrass prairie(Colorado State University. Libraries, 2005) St. John, Mark George. author; Wall, Diana H., advisor; Hunt, H. William, committee member; Kondratieff, Boris C., committee member; Seastedt, Timothy R., committee member; Stohlgren, Thomas J., committee memberHuman activities are responsible for unprecedented extinction rates and global change. Species are disappearing faster than we can record their existence and before we determine their role in ecosystems. In no other system on Earth are we more uncertain about the true diversity of organisms and their roles than in soils. I have examined soil mite (Acari) species at the Konza Prairie Biological Station (KPBS), Kansas, USA, an uncultivated tallgrass prairie, to determine what mechanisms are responsible for their diversity, how alien invasive grasses may impact them, and what role their diversity plays in decomposition. The hypotheses that soil mite species richness, abundance and taxonomic diversity is greater beneath grasses in dicultures (different species) compared to monocultures (same species), beneath grasses of higher resource quality (lower C:N) compared to lower resource quality, and beneath heterogeneous mixes of grasses (C3 andC4 grasses growing together) compared to homogeneous mixes (C3 or C4 grasses) were tested using natural occurrences of grass species as treatments. Increased grass diversity supported a more species and phylogenetically rich soil mite fauna. This relationship was significant at depth but not in the upper soil horizon. Soil mite richness increased nonlinearly with grass species richness suggesting that simple extrapolations of soil faunal diversity based on plant species inventories may underestimate the richness of associated11lsoil mite communities. The proportion of mite size classes in dicultures was considerably different than those for monocultures. These data suggest that interspecific root competition results in increased mite habitat, abundance and diversity. There was no difference in soil mite richness between grass combinations of differing resource quality, or resource heterogeneity. Soil mites sampled beneath six native and one alien-invasive species of grass were similarly abundant, species rich, diverse, and taxonomically distinct. There was no evidence that the community composition of soil mites was specific to grass species or that a significant number of mite species had affinities for different grass species. The soil mite community was weakly related to soil environmental conditions. Only oribatid mites were related to, marginally, the species of grass present. The alien invasive grass species did not support a successionally younger mite fauna and had no influence on mite community structure, possibly because it had not substantially altered the soil environment. Rates of cotton strip decomposition (percent cotton strip tensile strength loss per day, CTSL), and soil mite abundance and species richness were measured at high and low fire frequency sites of the KPBS. Likelihood-based and information theoretic approaches were used to examine strength of evidence in data for models of CTSL representing the Null, Rivet and Redundant hypotheses of biodiversity and ecosystem function (BEF). The Null model including temperature, moisture and saturating effects in the total abundance of predatory mites (Mesostigmata) had more support in the data than any other models. Models representing Rivet and Redundant patterns of BEF settled on parameter values distinct from the Null models but had less support in the data regardless of which mite group was being considered. A significant trend was observed in the models' residuals from low fire frequency sites trends not observed in high fire frequency sites. I speculate that annually burned sites more closely emulate the agricultural system the models were originally designed for than low fire frequency sites, accounting for differences in model performance. Biophysical properties on low fire frequency sites such as increased litter cover, different soil carbon constituents or a different microbial community may regulate decomposition in a manner not accounted for by only soil temperature and moisture driving variables.
- ItemOpen AccessThe effects of grasshoppers on soil animal communities in the Shortgrass Steppe of northern Colorado(Colorado State University. Libraries, 2015) Post, Keith Harrison, author; Wall, Diana H., advisor; Knapp, Alan K., committee member; Kondratieff, Boris C., committee member; Ocheltree, Troy W., committee memberA burgeoning area of research in ecology is on the linkages between aboveground and belowground components of terrestrial systems. Leaf-feeding insects can affect soil communities directly via frass deposition or indirectly through alterations in the quantity or composition of plant roots or the amount of labile carbon exuded belowground. These pathways can affect the three soil energy channels (i.e., root, soil bacterial, and soil fungal) by altering the absolute and/or relative amounts of their source materials and, in turn, impact soil microbial community composition and higher trophic levels, including soil nematodes and microarthropods. This aboveground-belowground interaction is important to fully understanding the functioning of terrestrial ecosystems, especially in the context of global climate change. This study investigated the effects of short-term grasshopper exclusion in the shortgrass steppe of northern Colorado on plant abundance and temporal changes in trophic groups of soil animals. Above- and belowground plant biomass, soil nematode, and soil microarthropod responses to altered grasshopper abundances were determined using grasshopper exclosures and caged controls from late summer–early fall 2014. Plant community composition during the study was drastically different than long-term data. Bouteloua gracilis, a co-dominant grass, was reduced to an average of 5.75% of total aboveground biomass, whereas the typically rare, annual grass Vulpia octoflora exploded to over 93%. Total above- and belowground plant biomass and aboveground biomass from V. octoflora and other grasses (mainly B. gracilis) were unaffected by grasshopper exclusion. Grasshopper feeding enhanced the ratio of bacterivorous to fungivorous nematodes, which remained similar through time in exclosures. Proportions of bacterial-feeding nematodes increased in caged controls but decreased in exclosures, while there was a trend for the opposite pattern for plant parasitic nematodes. Temporal changes in the densities of soil microarthropods, mites, and mite trophic groups were similar between cage types. Results indicate that grasshoppers enhanced the relative dominance of the soil bacterial energy channel, likely through greater frass deposition. Apparent exclosure effects on plant parasitic nematodes suggest a possible belowground plant response to altered grasshopper populations, which could have been weak because these effects were specific to the then-rare B. gracilis, which was about to enter senescence. Implications of this research in the context of global climate change, particularly droughts in the shortgrass steppe, are discussed.
- ItemOpen AccessThe impacts of metal-contamination and fine sediment deposition on benthic macroinvertebrate communities(Colorado State University. Libraries, 2017) Dabney, Brittanie Lee, author; Clement, William H., advisor; Winkelman, Dana L., committee member; Kondratieff, Boris C., committee memberTo view the abstract, please see the full text of the document.