Theses and Dissertations at Montana State University (MSU)
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Item Can conservation biocontrol of wheat stem sawfly be improved? Contributions of supplemental nutrition to longevity, egg load, and egg volume of Bracon cephi and B. lissogaster(Montana State University - Bozeman, College of Agriculture, 2022) Cavallini, Laissa; Chairperson, Graduate Committee: David K. Weaver; This is a manuscript style paper that includes co-authored chapters.Wheat stem sawfly (WSS), Cephus cinctus, is a major pest of wheat, causing losses that exceed $350 million annually across the Northern Great Plains. Two native parasitoids, Bracon cephi and B. lissogaster, suppress C. cinctus populations in wheat fields, where the immatures feed on and kill C. cinctus larvae. The success of natural enemies is linked to access to supplemental food in the field, which increases their life span and benefits their reproductive parameters. To assess the benefits that supplemental nutrition might have on B. cephi and B. lissogaster, we reared adult females on carbohydrate-rich diets combined with and without amino acids, with water and water plus amino acids as controls. We also conducted greenhouse experiments with the non-native, warm-season cover crop cowpea, Vigna unguiculata, as an extrafloral nectar source for parasitoids. Cages containing individual females were placed on living plants enclosing either cowpea inflorescence stalk extrafloral nectar (IS-EFN) or the leaf stipel extrafloral nectar (LS-EFN), with a supply of water as the negative control and buckwheat nectar as the positive control. In both lab and greenhouse experiments, females were observed daily to assess longevity, while egg load and volume were assessed 2, 5, and 10 days after placement. Results show that both species increased longevity when provided carbohydrate-rich food. B. cephi enhanced egg load and volume with carbohydrate-rich diets, and the addition of amino acids tending to benefit these parameters. Results show that IS-EFN increases longevity in both parasitoids. B. lissogaster kept constant egg load and volume, while B. cephi increased reproductive parameters with IS-EFN. These native braconid parasitoids are unfamiliar with non- native cowpea plants. Hence, we tested their attraction to cowpea volatiles, where positive responses were observed. Our results show that supplemental nutrition greatly benefits B. cephi and B. lissogaster females, with cowpea IS-EFN improving their longevity and reproductive parameters. Therefore, we suggest that cowpea has potential to be considered as a food supplement crop in conservation biocontrol programs to reduce WSS populations.Item Assessment of variation in the detection and prevalence of blood parasites among sympatrically breeding geese in western Alaska(Montana State University - Bozeman, College of Letters & Science, 2021) Buchheit, Raymond Matthew; Chairperson, Graduate Committee: Jay J. Rotella; Joel A. Schmutz, Brian Uher-Koch and Andrew M. Ramey were co-authors of the article, 'Assessment of variation in the detection and prevalence of blood parasites among sympatrically breeding geese in western Alaska' submitted to the journal 'Journal of wildlife diseases' which is contained within this thesis.Haemosporidian parasites may impact avian health and are subject to shifts in distribution and abundance with changing ecological conditions. Therefore, understanding variation in parasite prevalence is important for evaluating biologically meaningful changes in infection patterns and associated population level impacts. Previous research in western Alaska indicated a possible increase in Leucocytozoon infection between emperor geese (Anser canagicus) sampled in 1996 (<1%, n=134), and during 2011-2012 (19.9%, 95% CI: 3.0-36.8%, n=77); however, different detection methods were used for these estimates. Prior research in this same region identified a lack of Leucocytozoon parasites (0%, n=117) in sympatrically breeding cackling geese (Branta hutchinsii minima) in 2011. In this study, we molecularly screened blood samples collected from sympatrically breeding emperor and cackling geese in western Alaska during additional breeding seasons to better assess temporal and species-specific variation in the prevalence of blood parasites. We found similar prevalence estimates for Leucocytozoon parasites in emperor goose blood samples collected in 1998 and 2014, suggesting consistent infection of emperor geese with blood parasites at these time points. Using samples from sympatric geese sampled during 2014, we found evidence for higher incidence of Leucocytozoon parasites among emperor geese (20.3%, 95% CI: 11.8-32.7%) as compared to cackling geese (3.6%, 95% CI: 1.1-11.0%) reinforcing the previous finding of species-specific differences in infection. Furthermore, we detected Leucocytozoon, Haemoproteus, and Plasmodium blood parasites in unflighted goslings of both species, supporting the possible transmission of these parasites at western Alaska breeding grounds. Our results help to clarify that prevalence of Leucocytozoon parasites have likely remained consistent among emperor geese breeding in western Alaska since the late 1990s and that this species may disproportionally harbor Leucocytozoon parasites as compared to sympatrically breeding cackling geese.Item Developing and implementing genetic tools designed to understand host takeover by Chlamydia trachomatis.(Montana State University - Bozeman, College of Letters & Science, 2019) Kessy, Enock Joel; Chairperson, Graduate Committee: Blake WiedenheftChlamydia are gram negative obligate intracellular parasites that are responsible for millions of new infections in humans and animals every year. C. trachomatis is the number one cause of bacterial sexually transmitted infections in the United States, the number one cause of infectious blindness worldwide. Since 2001, there has been a steady increase in the number of new cases of C. trachomatis infections each year. Despite the prevalence and medical importance of C. trachomatis, we still know relatively little about the lifecycle of this parasite and the host factors that are essential for the lifecycle of C. trachomatis. To address this critical gap in our knowledge, my thesis work aimed to develop and implement genetic tools to understand host takeover by C. trachomatis. In this thesis I present results suggesting that I have transformed C. trachomatis with a plasmid carrying the Cas9 gene from Campylobacter jejuni. Additional experiments are necessary to determine if the CjCas9 is expressed, nuclease active, and functional for programable editing in C. trachomatis. In addition to my work aimed at developing a CRISPR-Cas9-based genetic engineering system in C. trachomatis, I also participated in a genome wide knockout screen aimed at identifying human genes necessary for completion of the C. trachomatis lifecycle. The CRISPR-Cas9 genome wide knockout screen identified 103 genes as critical factors for C. trachomatis. To validate results for the screen I have been involved in creating clonal cell lines with deletions in three of the genes that form the Adaptor Protein (AP) Complex (i.e., AP3S2, AP1B2 and AP1G2). The genes have been deleted and future experiments are aimed at measuring the impact of these genes on the C. trachomatis lifecycle.Item Impacts of dryland farming systems on biodiversity, plant-insect interactions, and ecosystem services(Montana State University - Bozeman, College of Agriculture, 2018) Adhikari, Subodh; Chairperson, Graduate Committee: Fabian D. Menalled; Laura Burkle (co-chair)Farming system impacts the structure and functioning of associated biodiversity and plant-insect interactions. However, the extent of these impacts is largely unknown in drylands of the Northern Great Plains, an important region for cereal, pulse, oilseed, and forage production. Using three complementary studies, I compared the impacts of conventional and organic systems on associated biodiversity (weeds, bees, insect pests, and parasitoids), bee-flower networks, and bumblebee colony success. First, I assessed stem cuts by and parasitism on Cephus cinctus (wheat stem sawfly) in spring and winter wheat cultivars grown in conventional and organic fields. I found that organic fields had less C. cinctus infestation and more braconid parasitoids of C. cinctus, indicating an increased pest regulation in organic system. I compared C. cinctus preference and survival on Kamut with Gunnison and Reeder wheat cultivars and found the lowest C. cinctus oviposition and survival in Kamut, suggesting that Kamut is a potential genetic source for this pest. Second, I assessed the impacts of conventional and organic systems on forb and bee communities. I found greater forb diversity and more connected bee-flower networks in organic fields, but bee communities did not differ between systems. Comprising only 12% of the landscape, natural habitat did not affect small-bodied bees in either system but had a positive effect on large-bodied bees at the scale of 2000 m radius. These results indicate that an increased forb diversity and bee-flower interaction in organic fields is not enough to offset the negative effects of landscape homogeneity on bees. Third, I compared Bombus impatiens colony success, worker condition, and colony-collected pollen between farming systems. I found greater growth rate, brood cells, and pollen species richness in B. impatiens colonies as well as lower wing wear and greater body lipid mass in workers from organic fields, than in conventional fields. The greater colony success and better worker conditions could be a proxy for better ecosystem services provided by organic fields. Overall, my studies show that organic farming supports greater associated biodiversity, more complex bee-flower networks, and better biodiversity-based ecosystem services in the Northern Great Plains.Item The potential of sugar resources in the reproductive biology of wheat stem sawfly parasitoids(Montana State University - Bozeman, College of Agriculture, 2018) dos Reis, Dayane Andrade; Chairperson, Graduate Committee: David K. Weaver; Robert K. D. Peterson, Megan L. Hofland and David K. Weaver were co-authors of the article, 'Differences in longevity, egg load, and egg volume due to sucrose feeding in two sympatric congeneric braconids that are specialist parasitoids of the wheat stem sawfly ' which is contained within this thesis.; Robert K. D. Peterson, Megan L. Hofland and David K. Weaver were co-authors of the article, 'The effect of cultivated and native floral species as resources in the reproductive biology of wheat stem sawfly parasitoids' which is contained within this thesis.The wheat stem sawfly, Cephus cinctus, is the most destructive insect pest of wheat, Triticum aestivum, in the Northern Great Plains of North America. Biological control by Bracon cephi and Bracon lissogaster is an important tool for integrated pest management of this pest, but parasitism rates are difficult to predict. Therefore, the main objective of this research was to characterize aspects of the reproductive biology of both parasitoid species to provide information that could enhance their effectiveness in biological control of C. cinctus. First, we investigated the role of diapause and the effects of sucrose feeding on reproduction of females. For that, we provided sucrose solution to overwintering and summer generation adult females, and we quantified and compared their longevity, egg load and egg volume. Our results showed no differences between overwintering and summer individuals of B. cephi and B. lissogaster. In contrast, sucrose feeding, increased longevity and egg load of both species and generations. The egg load of B. cephi was surprisingly low compared to B. lissogaster. However, only B. cephi increased egg volume when sucrose was provided. Our findings highlighted the contrasting life histories of both species, and showed the potential of sugar resources in enhancing their reproductive capacity. Subsequently, we investigated the effect of flower nectar on the same, above mentioned, reproductive traits of parasitoids. We chose buckwheat (Fagopyrum esculentum), lacy phacelia (Phacelia tanacetifolia), deerhorn clarkia (Clarkia pulchella), canola (Brassica napus), and safflower (Carthamus tinctorius) based on their occurrence as native plants, use in pollinator enhancement, and occurrence in rotational or cover crop plantings in Montana. We found that only B. cephi females benefitted from these flowering plants. The longevity and egg volume of females increased with buckwheat, and egg volume increased with both buckwheat and the native species, deerhorn clarkia. The strong effect of buckwheat on reproduction of B. cephi females suggests that flowers with similar nectar quality might have similar impacts. This information will be of great importance for selection of suitable flower species to enhance reproductive capacity of parasitoids through habitat management. Collectively, this research showed that there is potential to enhance effectiveness of parasitoids with sugar supplementation.Item Mortality dynamics and life tables of Megachile rotundata(Montana State University - Bozeman, College of Agriculture, 2019) Donahoo, Claire Katherine; Chairperson, Graduate Committee: Robert K. D. Peterson.; Kevin M. O'Neill, Casey M. Delphia and Robert K. D. Peterson were co-authors of the article, 'Mortality dynamics and life tables of the alfalfa leafcutting bee, Megachile rotundata (Hymenoptera: Megachilidae)' which is contained within this thesis.The alfalfa leafcutting bee, Megachile rotundata (F.), contributes to the pollination of more than two-thirds of alfalfa seed production in North America. However, population losses of more than 50% are common in the U.S., requiring many alfalfa seed producers to import costly bees from Canada. Understanding the mortality dynamics of M. rotundata and being able to estimate these impacts on their populations are critical for identifying ways to conserve and increase their populations. Therefore, this study had three objectives: 1) identify mortality classes for M. rotundata in brood cells; 2) experimentally manipulate parasitism and temperature to determine their impact on total mortality; and 3) estimate mortality risks using the multiple-decrement life table (M-DEC). Research was conducted over two years on a 38.5 ha alfalfa field in Toston, MT. Nest shelters were manipulated for a main temperature treatment (low vs. high) and a sub-treatment for parasitism (backing-present vs. backing-absent). Females constructed and provisioned nests during the summer and offspring mortality was assessed during the summer and the following fall. Mortality classes were then analyzed using the M-DEC model. We found no temperature-treatment effect, so our main treatment was not used in the analyses. However, for every 1 °C increase in nest-tunnel temperature, there was a 7% increase in total mortality. Nest boxes without felt backing (backing-absent) had a 43% increase in mortality over both years compared to those with felt (backing-present). Average temperature decreased by 4.4 °C from 2017 to 2018, while average relative humidity increased by 12.1%. Total mortality was approximately 15% for both years, but the proportion of each mortality class differed substantially, with death by parasitoids greatest in 2017 and death by pollen ball greatest in 2018. Mortality from each class was highly irreplaceable in that it is unlikely to be replaced by another class, and death by predation was the only cause with similar mortality between the two years. The ability to identify and quantify mortality classes and their respective irreplaceable mortality, especially for parasitoids, pollen ball, and predators, will help producers maintain and increase bee populations.Item Implementation of culturally sensitive and informed health education as a part of the 'wash approach' to controlling soil-transmitted helminth infections in the rural village of Bati Kelo, east Shewa Zone, Adama Wereda, Ethiopia(Montana State University - Bozeman, College of Nursing, 2017) Dean, Courtney Elizabeth; Chairperson, Graduate Committee: Elizabeth KinionProblem Statement: A lack of population-specific approaches and interventions exist with regards to soil-transmitted helminth control measures, thus resulting in significantly reduced effectiveness and lasting impact. Purpose: The purpose of this clinical project was to develop and implement a culturally sensitive and informed health education program to address the health practices of a rural high risk population as a method for controlling soil-transmitted helminth infections. Methods: A culturally sensitive and informed health education program, utilizing the holistic method of the 'WASH Approach,' was implemented in the community of Bati Kelo, East Shewa Zone, Adama Wereda, Ethiopia. The project intervention consisted of three key components: 1) developing a culturally competent and population-specific KAP survey, 2) developing culturally competent health education material for the project population, and 3) conducting the KAP survey and health education sessions in a culturally competent manner. A convenience sample of 234 individuals was collected from the community. The project data were based on self-reported responses to the KAP survey. Ten key health behavior questions were utilized to evaluate the project: two on latrine usage, three on clean water usage, three on hand washing, and two on wearing shoes. Eighty-one surveys qualified for final inclusion. Data were analyzed using SPSS version 2.4. Descriptive statistics were utilized for the evaluation of the entire project. McNemar's test was used to analyze the differences between pre and post intervention (survey) results involving dichotomous variables. Wilcoxon's signed-rank test was used to analyze the differences between pre and post intervention (survey) results involving paired ordinal data. Findings: Positive health behavior/practice change was demonstrated post-intervention in the areas of 'latrine use,' 'clean water (treating water),' and 'handwashing;' however, it was not shown in the area of 'wearing shoes.' Conclusions: The overall findings of this clinical project were consistent with prior research studies, which found the WASH approach impactful on STH infection prevention measures (health behavior practices). A gap in the literature regarding 'cultural competence' in health education as a part of the WASH approach and STH control measures still exists. Much more inquiry and work still remains to be done.Item Breeding for root lesion nematode resistance in Montana winter wheat(Montana State University - Bozeman, College of Agriculture, 2015) May, David Bruce, III; Chairperson, Graduate Committee: Philip L. BrucknerRoot lesion nematodes (RLN; Pratylenchus spp.) present a serious challenge to dryland wheat production worldwide. Development of resistant cultivars would provide great economic benefit to growers. From 2012-2013, a set of backcross lines (MT08185//MT08184/Persia 20) was screened twice for resistance to P. neglectus. Progeny and parent lines were grown in infested soil for 16 to 18 weeks. Nematodes were then extracted from roots of individual plants and counted to obtain per plant final populations. ANOVA results from the 2013 screen showed significant differences in mean P. neglectus populations among lines (p < 0.01). The median final population of susceptible parent MT08184 was an estimated 4.9 times greater than that of resistant parent Persia 20. A 2013 field trial in the absence of root lesion nematodes indicated reductions in grain yield, volume weight, and protein were not associated with resistance. Seven RLN-resistant lines were identified in field evaluations with agronomic phenotypes for yield, volume weight and protein comparable to those of five widely-grown checks. Identification of quantitative trait loci (QTL) for resistance to RLN will facilitate marker-assisted introgression of resistance genes in a backcross-breeding program. Single-marker analysis of 218 genome-wide single nucleotide polymorphism markers (SNPs) was performed to identify genomic regions associated with resistance to P. neglectus. The analysis identified putative marker-trait associations on chromosomes 1AL, 1DS, 2BL, 5BL, 5DL, 7AL and 7DL (all p < 0.05). Overall, phenotypic screens as applied were inadequate to consistently characterize wheat lines for RLN resistance. As such, RLN resistance phenotypes and putative QTL effects identified in the study must be verified in future experiments.Item Geothermal habitats as sites for year-round transmission of Fasciola hepatica(Montana State University - Bozeman, College of Agriculture, 1995) Potts, Robert StanleyItem Isolation and partial characterization of macrophages from bovine peripheral blood(Montana State University - Bozeman, College of Agriculture, 1990) Mukherjee, Goutam