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Item Exploring the potential of entomopathogenic nematodes against wireworms in Montana(Montana State University - Bozeman, College of Agriculture, 2020) Sandhi, Ramandeep Kaur; Chairperson, Graduate Committee: Michael A. Ivie; David Shapiro-Ilan, Anamika Sharma Gadi V P Reddy were co-authors of the article, 'Efficacy of available entomopathogenic nematode strains against Limonius californicus (Mannerheim)' in the journal 'Biological control' which is contained within this dissertation.; Ratnasri Pothula, Satyendra K. Pothula, Byron J. Adams, Gadi V.P. Reddy were co-authors of the article, 'First record of native entomopathogenic nematodes from Montana agroecosystems' in the journal 'Journal of nematology' which is contained within this dissertation.; David Shapiro-Ilan and Gadi V.P. Reddy were co-authors of the article, 'Montana native entomopathogenic nematode species against Limonius californicus (Coleoptera: Elateridae)' in the journal 'Journal of economic entomology' which is contained within this dissertation.; David Shapiro-Ilan, Gadi V P Reddy and Michael A. Ivie were co-authors of the article, 'Efficacy of entomopathogenic nematode infected insect cadavers against wireworms in greenhouse and field' submitted to the journal 'Pest management science' which is contained within this dissertation.; Gadi V P Reddy, David Shapiro-Ilan and Michael A. Ivie were co-authors of the article, 'Effect of soil texture, soil moisture, and soil temperature on efficacy of entomopathogenic nematode strains against wireworms under laboratory conditions' submitted to the journal 'Journal of applied entomology' which is contained within this dissertation.Wireworms (Coleoptera: Elateridae), are important soil-dwelling pests and have become a serious threat to spring wheat in the Northern Great Plains because of lack of effective control measures, creating a need for alternative control methods such as biological control with entomopathogenic nematodes (EPNs). Ten EPN strains were tested against sugarbeet wireworm, Limonius californicus (Mannerheim) in laboratory bioassay. Out of these ten strains, Steinernema carpocapsae (Weiser) (All and Cxrd strains) and S. riobrave Cabanillas, Poinar, and Raulston (355 and 7-12 strains) were found effective in laboratory and shade house. However, the dose required to kill at least 50% of the treated L. californicus larvae was 200 infective juveniles/cm 2. Two Montana native EPN species (S. feltiae and Heterorhabditis bacteriophora) were extracted and were evaluated against L. californicus in laboratory and shade house. Although, 50% mortality was observed due to S. feltiae isolates in laboratory conditions, none of the two isolates of S. feltiae performed well against L. californicus in shade house. Steinernema carpocapsae and S. riobrave in the form of infected Galleria mellonella L. cadavers were evaluated against wireworms (L. californicus and H. bicolor) in field and greenhouse. In field, none of the four EPN strains were found effective in reducing wireworm populations or protecting crop yield in both spring wheat and barley fields. However, only one infected Galleria cadaver of S. carpocapsae (All and Cxrd) and S. riobrave 355 was able to kill wireworm larvae as well as reduce wheat plant damage in greenhouse. The imidacloprid treatment enhanced the infection and killing ability of EPNs against L. californicus. Steinernema carpocapsae All and Cxrd were able to kill 30-46% of L. californicus larvae in all four soil types tested as compared to S. riobrave 355 and 7-12 strains, when maintained at field capacity moisture levels. However, S. carpocapsae All and Cxrd strains were able to infect 35-50% wireworm larvae in sandy loam and clay loam soil type at standardized moisture (18%). Steinernema carpocapsae All and Cxrd killed greater wireworm numbers at 16% moisture level and 25 °C as compared to other moisture and temperature levels in sandy clay loam soil. These results indicate that EPN based strategies could be useful for wireworm management but need to be explored further under field conditions. This strategy can at least be part of a large Integrated Pest Management system for wireworm control in Montana.Item The effects of increasing crop diversity on populations of wheat stem sawfly (Cephus cinctus) and associated braconid parasitoids(Montana State University - Bozeman, College of Agriculture, 2019) Fischer, Benjamin Vernon; Chairperson, Graduate Committee: David K. WeaverWheat stem sawfly, Cephus cinctus (Norton) (WSS) is the most damaging pest of wheat in the Northern Great Plains. Insecticides are not widely used to control this insect, and cultural control methods provide inconsistent management of this pest. However, biological control by the parasitoids Bracon cephi (Gahan) and Bracon lissogaster Muesebeck has been shown to reduce damage caused by WSS. In addition, increased agroecosystem diversity has benefitted biological control agents in many other systems. Therefore, this study assessed the effect on populations of WSS and associated parasitoids by the inclusion of pulse and cover crops near wheat fields. Field trapping, dissection of postharvest crop residue, and rearing of insects out of crop residue were used to survey WSS and parasitoid populations in pairs of wheat fields throughout the major wheat producing regions of Montana. One wheat field in each pair was seeded next to a fallow field, and the other was seeded next to a field of either pulse or cover crop. Postharvest stem dissection samples show that wheat fields next to pulse or cover crops had a mean increase of 51 parasitoids per m 2 than wheat fields next to fallow. A corresponding 3% reduction in stem cutting was also observed in postharvest samples from wheat fields adjacent to flowering pulse or cover crops. Land-use data from CropScape TM were used as well to evaluate other land-use impacts around each wheat field such as wheat, fallow, grassland/pasture, flowering crops, and developed space. The regression equation Y = 18.96X + 6.08, where X = proportion of fallow land within 2 km of the wheat field and Y = square root of WSS abundance in a 7.5 m sample of crop residue from rows of wheat, can be used to predict WSS abundance in wheat fields. Replacing fallow fields with flowering pulse or cover crops in the Northern Great Plains may be an important integrated pest management tactic to reduce WSS damage. Cultural practices such as crop diversification are key to developing consistent biological control for WSS.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 Natural enemy abundance and biological control in Bt maize using simulations of predator-prey interactions(Montana State University - Bozeman, College of Agriculture, 2017) Brown, Christopher Regan; Chairperson, Graduate Committee: Robert K. D. Peterson; Laura A. Burkle, Daniel Salinas Duron, Adam Schapaugh, Christopher K. Sehy, Paul C. Stoy, David K. Weaver, Jeffrey D. Wolt and Robert K. D. Peterson were co-authors of the article, 'Simulating interactions between natural enemies and pests in maize to assess the influence of alternative food, cannibalism, and intraguild predation' which is contained within this thesis.; Laura A. Burkle, Daniel Salinas Duron, Adam Schapaugh, Christopher K. Sehy, Paul C. Stoy, David K. Weaver, Jeffrey D. Wolt and Robert K. D. Peterson were co-authors of the article, 'Simulating interactions between natural enemies and prey in Bt and conventional maize' which is contained within this thesis.The potential effects of genetically modified maize expressing insect-resistant proteins from Bacillus thuringiensis (Bt) on natural enemies represent an active area of research highlighting considerable interest in understanding even subtle perturbations in agroecosystems. In the case of Bt maize, indirect effects on natural enemies may occur due to a reduced prey base caused by the desired effect of pest control by the Bt plant. Although these indirect effects may be subtle and difficult to study in the field, a modeling approach offers an alternative, allowing factors related to these subtle effects to be easily explored. In this effort, simulations of interactions between maize, two pests (the European corn borer (ECB) and an aphid), and two natural enemies (a lady beetle and green lacewing) were made using a modified TrophicLink model. TrophicLink is an individual-based model that uses functional ecology and food web network theory to simulate the trophic interactions of individuals and the resulting flow of energy. The individual-based model approach emphasizes the unique experiences of individuals and their trophic interactions leading to system level effects. Pollen utilization, cannibalism, and intraguild predation by natural enemies were simulated to explore the influence of these factors and to test the model. The model performed well in terms of reasonable representation of trophic functional types and interactions between them. The natural enemies were able to reduce a lepidopteran pest population and partially protect yield. The presence of pollen was influential in natural enemy population sizes and the biological control they provide. Cannibalism and intraguild predation caused notable reductions in natural enemy populations, but only small differences in biological control levels. In a second set of simulations involving Bt maize, prey-reduced scenarios included a short-term Bt maize scenario with ECB eggs and young larvae, and a second scenario without any ECB representing regional suppression of ECB by wide adoption of the Bt maize. Lady beetle and green lacewing population mass were similar across scenarios indicating resiliency of the generalist natural enemies to prey removal in the scenarios simulated. These findings are consistent with field study data that have not found consistent effects of Bt maize on natural enemies.Item Genetic basis of wheat resistance to the wheat stem sawfly(Montana State University - Bozeman, College of Agriculture, 2016) Varella, Andrea Correa; Chairperson, Graduate Committee: Luther E. Talbert; Luther E. Talbert, Robert K. D. Peterson, Jamie D. Sherman, Nancy K. Blake, Megan L. Hofland, John M. Martin and David K. Weaver were co-authors of the article, 'Host plant quantitative trait loci affect specific behavioral sequences in oviposition by a stem-mining insect' submitted to the journal 'BMC plant biology' which is contained within this thesis. [SUBMITTED]; Megan L. Hofland, Micaela Buteler, Luther E. Talbert, Jamie D. Sherman, Nancy K. Blake, Hwa-Young Heo, John M. Martin and David K. Weaver were co-authors of the article, 'Temporal patterns of pith expression and retraction in wheat stems and its effect on resistance to the wheat stem sawfly' submitted to the journal ' ' which is contained within this thesis. [SUBMITTED] [NO MAG]; David K. Weaver, Jamie D. Sherman, Nancy K. Blake, Hwa-Young Heo, Jay Kalous, Shiaoman Chao, Megan L. Hofland, John M. Martin, Kenneth D. Kephart and Luther E. Talbert were co-authors of the article, 'Association analysis of stem solidness and wheat stem sawfly resistance in a panel of North American spring wheat germplasm' submitted to the journal 'Crop sciences' which is contained within this thesis. [PUBLISHED]The wheat stem sawfly, Cephus cinctus Norton (WSS), has been a serious pest of wheat in the Northern Great Plains of North America for decades. Host plant resistance has been most consistently effective and is the foundation for integrated pest management of the WSS; therefore, the main objective of this research was to enhance the repertoire of genetic resistance to WSS available for exploitation by wheat breeders through marker-assisted selection (MAS). We used two strategies to achieve our goal. First, we better characterized resistance provided by previously identified quantitative trait loci (QTL). For that, we developed populations of near-isogenic lines (NILs) polymorphic for resistance QTLs on chromosomes 2D (Qwss.msub-2D), 3B (Qss-msub-3BL) and 4A (Qwss.msub-4A.1). Near-isogenic lines were tested greenhouse cage trials and in the field at both WSS-infested and uninfested locations. The Qwss.msub-4A.1 was shown to affect host plant attractiveness to foraging females, but did not change oviposition preference after females landed on the wheat stem. The Qwss.msub-2D and Qss-msub-3BL where shown to be associated with decreased preference for oviposition. The Qss-msub-3BL was also shown to be associated with temporal patterns of stem solidness expression, with the allele derived from the spring wheat cultivar Conan providing decreased infestation, high neonatal mortality, high levels of early stem solidness, and a rapid rate of pith retraction during stem maturation. Together, these studies characterized the effect of each one of these QTLs on WSS resistance. This information will help wheat breeders and entomologists to better integrate management strategies to reduce damage caused by the WSS. Our second strategy, involved the identification of new marker-trait associations for WSS resistance. For that, we used a panel of 244 elite spring wheat lines from North America. By conducting an association mapping study we were able to identify several QTLs for WSS resistance, including QTLs for early and late stem solidness, heading date, stem cutting, and larval mortality. This study showed that improvements in WSS management may be obtained using alleles that already exist in elite germplasm. Collectively, our research provided wheat breeders with a better tool kit for improving resistance to the WSS.Item Impacts of three insect growth regulators and the particle barrier film, Kaolin, on alfalfa weevil, Hypera postica (Gyllenhal), secondary pest, pea aphid, Acyrthosiphon pisum (Harris) & natural enemy complex(Montana State University - Bozeman, College of Agriculture, 2015) Tharp, Cecil Irwin; Chairperson, Graduate Committee: Mary BurrowsStudies were conducted in Montana to evaluate the impacts of the insect growth regulators novaluron, diflubenzuron, azadirachtin and the particle barrier film, kaolin, on the primary pest, alfalfa weevil (AW, Hypera Postica [Gyllenhal)], natural enemies of alfalfa weevil and the secondary pest, pea aphid, Acyrthosiphon pisum (Harris). Kaolin, diflubenzuron and azadirachtin treatments caused low (<53%) AW mortality and did not prevent AW feeding damage across 5 field sites. Novaluron caused the highest mortality (74 ± 3% at one field site) while significantly reducing feeding damage across two of five field sites (P < 0.05) and two greenhouse trials. Plants treated with novaluron weighed significantly more than untreated plants at harvest in either greenhouse study with a final harvest weight of 2.7 ± 0.2 and 3.4 ± 0.3g / pot in the novaluron treated pots compared to 2.2 ± 0.1 and 2.4 ± 0.3 g / pot in the untreated; however harvest yields were not increased in field trials. All experimental treatments provided some pre-harvest benefits to the predator-alfalfa weevil and predator-pea aphid complex at various field sites; however novaluron treatments provided significantly higher predator-alfalfa weevil ratios consistently across four of five field sites when compared to the synthetic pyrethroid, lambda cyhalothrin (P < 0.05). At these four field sites, novaluron treated plots harbored an average predator-alfalfa weevil ratio of 0.15 ± 0.07 compared to 0.02 ± 0.02 in lambda cyahlothrin treated plots in the first harvest cycle. Parasitism rates were significantly higher when experimental treatments were used compared to the lambda cyhalothrin treated plots across five field sites (P < 0.05). The added benefit of conserving predators and parasitoids in combination with direct pesticide efficacy never reduced densities of AW or pea aphid to that of the synthetic pyrethroid treatment in the first or second harvest cycle. While novaluron had little benfit on reducing AW or pea aphid poulations to that of the synthetic pyrethroid treatment, it offers the best potential for developing a soft-chemical/biological system for protecting alfalfa from this key arthropod pest. Future studies taking advantage of novalurons mode of action as a feeding deterrent should be explored.Item The millipede of Santo Antao, Spinotarsus caboverdus : survey for pathogenic microorganisms, bioassay tests of fungal pathogens against S. caboverdus and Melanoplus sanguinipes(Montana State University - Bozeman, College of Agriculture, 1994) Brito, Jorge MendesItem Isozyme analysis of Paecilomyces farinosus and Paecilomyces fumosoroseus (Deuteromycotina: Hypomycetes), two potential biological control agents of the sweet potato and silverleaf whiteflies (Bemisia spp.)(Montana State University - Bozeman, College of Agriculture, 1995) Bunnell, Joseph E.Item Temperature-sensitive Beauveria bassiana mycosis in the Mormon cricket, Anabrus simplex(Montana State University - Bozeman, College of Agriculture, 1998) Turnbow, Jonathan HunterItem Pathogenicity of Vairimorpha sp. (Nosematidae: Microsporida) in the Mormon cricket, Anabrus simplex (Tettigoniidae: Orthoptera)(Montana State University - Bozeman, College of Agriculture, 1991) Currey, David Michael