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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 Evaluation of trap crops for the management of wireworms in spring wheat in Montana(Montana State University - Bozeman, College of Agriculture, 2017) Adhikari, Ashish; Chairperson, Graduate Committee: Gadi V. P. Reddy; Michael A. Ivie (co-chair); Gadi VP Reddy was a co-author of the article, 'Evaluation of trap crops for the management of wireworm in spring wheat in Montana' submitted to the journal 'Journal of economic entomology' which is contained within this thesis.Wireworms, the larval stage of click beetles, have slender, shiny, hard bodies with three pairs of legs. They are polyphagous and have cryptic habitats. In recent years, increasing wireworm numbers and damage have become a major problem for growers in the Golden Triangle Region of Montana. The control of this pest is very difficult because after the removal of Lindane by US Environmental Protection Agency (USEPA) in 2009, the use of the second generation insecticides have not been able to provide effective control of wireworms. Thus, using insecticides to control wireworms has not been effective at high population levels. Also, little is known about the biology and feeding habit of wireworms. The goal of this study is to evaluate trap crops that can protect the spring wheat by attracting wireworms. First, field trials were conducted at two locations to investigate on the use of peas Pisum sativum L. (Fabaceae), lentils Lens culinaris L. (Fabaceae), canola/rapeseed Brassica napus L. (Brassicaceae), corn/maize Zea mays L. (Poaceae), durum Triticum durum Desf. (Poaceae) and barley Hordeum vulgare L. (Poaceae) as traps intercropped with spring wheat Triticum aestivum L. (Poaceae). The efficacy of trap cropping was determined by damage assessment in wheat plants along 1m transects and by counting wireworm populations on wheat and trap crop rows of a plot. Secondly, the effect of intercrop spacing on plant damage and the number of wireworms was determined for pea and lentil trap crops. To support field trials potted experiments were set up in the shade house to determine wireworm distributions in two-choice assays. Collectively the results from this study showed that pea and lentil trap crops resulted in significantly lower damage in wheat plants and they attracted more numbers of wireworms compared to other crops. Results from shade house trails supported observations from the field trials. An intercropping spacing of 0.5m between pea or lentil and the spring wheat crop produced highest density of spring wheat plants. The results from these experiments will add to the basic understanding of trap cropping for wireworms control.Item Chemical control and disease reservoir studies of the wheat curl mite (Aceria tosichella Keifer), vector to wheat streak mosaic virus(Montana State University - Bozeman, College of Agriculture, 2016) Murphy, Carmen Yvette; Chairperson, Graduate Committee: Mary BurrowsWheat streak mosaic virus (WSMV) causes yield loss to wheat (Triticum aestivum) in all areas of the world where the crop is grown. No chemical controls for the WSMV vector, the wheat curl mite (WCM, Aceria tosichella Keifer), are approved. Control relies primarily on avoiding a 'green-bridge' of living plant material that can host the disease between seasons. This study aimed to 1) identify chemical treatments for WCM control under conventional and organic systems and clarify misconceptions that treatments, such as sulfur, control WCM and 2) analyze the capacity of 20 grassy species to serve as reservoirs of WSMV and WCM. The effects of insecticides with varying modes of action (carbamate, organophosphate, pyrethroid, neonicotinoid, biological control, oil, ovicide, mite growth inhibitor, and soap) on WCM population growth were tested in the greenhouse. Treatment with the active ingredients aldicarb and chlorpyrifos decreased WCM populations compared to untreated controls (p<0.001 and p<0.001). Field trials were conducted in spring wheat in 2013 and winter wheat in 2013-2014. Similar effects on WSMV spread were not observed in field trials. These trials included ten products consisting of five modes of action: organophosphates, pyrethroid, oil, soap and mite growth inhibitor. Chlorpyrifos was included in the field trials, but no efficacy was seen in 2013 compared to controls under good infection and incidence and infection was low in 2014, therefore we were unable to distinguish any treatment effect. To assess the capacity of 20 grassy species to serve as reservoirs of WSMV and WCM, plants with varying lifespan and origin were grown in the greenhouse and infested with viruliferous WCM. Lifespan had the greatest impact on ability of plants to host WCM (p=0.011) and WSMV (p<0.001). Annual plant species are more likely to host WCM than perennial grasses, with all species hosting WCM. Native and introduced species tested did not differ in ability to host WCM (p=0.735) and WSMV (p=0.096). This study provides evidence of potential for use of active ingredient chlorpyrifos in WCM control, and showed that lifespan is an important determinant of WSMV disease reservoir potential of grassy species.Item The composition of wireworm species in Montana wheat and barley fields and its effect on developing IPM programs(Montana State University - Bozeman, College of Agriculture, 2014) Morales-Rodriguez, Anuar; Chairperson, Graduate Committee: Kevin Wanner; Kevin W. Wanner was a co-author of the article, 'An evaluation of four different bait traps for sampling wireworms (Coleoptera: Elateridae) infesting cereal crops in Montana' submitted to the journal 'Journal of economic entomology' which is contained within this thesis.; Ruth P. O'Neill and Kevin W. Wanner were co-authors of the article, 'A survey of wireworm (Coleoptera: Elateridae) species infesting cereal crops in Montana' in the journal 'Pan-pacific entomologist' which is contained within this thesis.; Kevin W. Wanner was a co-author of the article, 'Determining the potential for cereal crop injury by wireworm species commonly found infesting cropland in Montana' submitted to the journal 'Canadian entomologist' which is contained within this thesis.; Kevin W. Wanner was a co-author of the article, 'Efficacy of thiamethoxam and fipronil, applied alone and in combination, to control Limonius californicus and Hypnoidus bicolor (Coleoptera: Elateridae)' in the journal 'Pest management science' which is contained within this thesis.; David Wichman and Kevin W. Wanner were co-authors of the article, 'Effects of cultural practices on wireworm populations and damage in cereal fields' submitted to the journal 'Crop sciences' which is contained within this thesis.Wireworms, the larvae of click beetles, are the most important soil-insect pest of small grain fields in Montana. Worldwide, there are about 9,300 species of elaterids in 400 different genera, and in North America 885 species in 60 genera have been identified. In Montana, 166 species were identified, among them, 21 species have been identified as possible pests in small grain fields and some are serious pests of a wide variety of crops. My research focused on three main objectives related to wireworm IPM: first, the identification of the species causing damage in the field and their geographic and seasonal distribution in Montana; second, establishing the potential of different baited traps to monitor pest wireworm populations; and third, evaluating chemical and cultural management alternatives. To complete the first objective a statewide wireworm survey was conducted for three years as well as an intense sampling of four cereal fields season for three consecutive years. To complete the second objective, the effectiveness of four baited traps were assessed: traditional pitfall compared to pot, stocking and canister type traps, in four cereal fields for three years. To complete the last objective, laboratory, greenhouse and field studies were conducted to evaluate new insecticides, crop injury, tillage practices and seeding density. 5,097 wireworms were collected from the four sites during 2010 - 2012 including four common species, Aeolus mellillus, Hypnoidus bicolor, Limonius californicus and L. infuscatus, and three minor species, Agriotes spp., Dalopius spp. and Selatosomus aeripennis. Peak wireworm activity at the soil surface was found to coincide with cereal crop germination and establishment. While all trap types can be used to detect wireworm activity and estimate population levels, pitfall and stocking were more efficient than pot and canister traps. Thiamethoxam does not kill wireworms but its ability to suppress wireworm populations in the field can be improved by the addition of fipronil. Increasing seeding density is one of the most common cultural recommendations for managing wireworms, but my studies did not support its benefit to higher crop yields. Significantly, species-specific crop injury and seasonal movement in the soil support the need for species-specific IPM research.Item Confirmation and management of glyphosate-resistant Kochia (Kochia scoparia) in Montana(Montana State University - Bozeman, College of Agriculture, 2015) Kumar, Vipan; Chairperson, Graduate Committee: Prashant Jha; Prashant Jha and Nicholas Reichard were co-authors of the article, 'Occurrence and characterization of Kochia (Kochia scoparia) accessions with resistance to glyphosate in Montana' in the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha, Darci Giacomini, Eric Westra and Philip Westra were co-authors of the article, 'Molecular basis of evolved resistance to glyphosate and acetolactate synthase-inhibitor herbicides in Kochia (Kochia scoparia) accessions from Montana' submitted to the journal 'Weed science journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Impact of EPSPS gene amplification and intraspecific competition on fitness of glyphosate-resistan Kochia scoparia inbreds' submitted to the journal 'PLoS one journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Effective preemergence and postemergence herbicide programs for Kochia control' in the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Influence of herbicides applied postharvest in wheat stubble on control, fecundity, and progeny fitness of Kochia scoparia in the US Great Plains' in the journal 'Crop protection journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Influence of glyphosate timing on Kochia (Kochia scoparia) demographics in glyphosate-resistant sugar beet' submitted to the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Control of volunteer glyphosate-resistant canola in glyphosate-resistant sugar beet' in the journal 'Weed technology journal' which is contained within this thesis.Kochia (Kochia scoparia L.) is one of the most problematic weeds in cropland and non-cropland areas of the US Great Plains. This research confirms the first report on glyphosate-resistant (GR) K. scoparia in Montana, and elucidates the mechanisms of glyphosate and ALS-inhibitor resistance, growth and reproductive fitness of GR K. scoparia, and its management. This research also reports the response of K. scoparia demographics to glyphosate timings in GR sugar beet and evaluate herbicide options for managing volunteer GR canola in GR sugar beet. Based on whole-plant dose-response experiments, four GR K. scoparia accessions (JOP01, GIL01, CHES01, CHES02) had 4.6 to 11-fold levels of resistance to glyphosate compared to a glyphosate-susceptible (GS) accession. Confirmed GR K. scoparia accessions (GIL01, JOP01, and CHES01) also exhibited 9.3- to 30-fold resistance to sulfonylurea herbicide (ALS inhibitors). Results from PCR, quantitative PCR, and immunoblotting assays indicated that EPSPS gene amplification (~ 4 to 10 copies) and single point mutation at Pro197 in ALS gene conferred resistance to glyphosate and ALS-inhibitors, respectively. Inbred lines of GR K. scoparia (CHES01 and JOP01) with 2- to 14-fold amplification of the EPSPS gene did not confer any growth- or fecundity-related fitness cost. From a management standpoint, acetochlor + atrazine, S-metolachlor + atrazine + mesotrione, and sulfentrazone applied PRE and paraquat + atrazine, paraquat + linuron, and paraquat + metribuzin applied POST or in postharvest wheat stubble provided effective (> or = 91%) control of K. scoparia. In GR sugar beet, sequential applications of glyphosate (6-leaf fb 10-leaf stage of sugar beet) reduced survival, biomass and seed production of K. scoparia plants in cohort 1 and 2; however, an additional application of glyphosate at the canopy closure stage of sugar beet was needed to prevent seed production from the late-emerging K. scoparia (cohort 3). Ethofumesate (4,200 g ha -1) PRE followed by sequential POST triflusulfuron methyl (17.5 g ha -1) was the most effective treatment for managing volunteer GR canola in GR sugar beet. Overall, this research demonstrates the adaptability of K. scoparia evolving resistance to glyphosate and ALS inhibitors, and suggest the need for adoption of integrated weed management practices.Item Inheritance of stem solidness and its relationship to yield and other agronomic traits in spring wheat(Montana State University - Bozeman, College of Agriculture, 1993) Hayat, Mohammad AslamThe wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), a devastating pest of wheat, has caused considerable economic damage in the Pacific Northwest. Solid-stemmed wheat varieties have provided a genetic source of resistance against the insect. However, solid-stemmed wheats tend to yield less than hollow-stemmed wheats. Some, but not all, studies have shown yield to be negatively related to stem solidness. To date, it is not clear whether solid-stemmed wheats have low yield due to a negative genetic correlation or to the poor genetic background of the original solid-stemmed selections. The cause of the negative association between solid stems and other traits was studied in spring wheat using solid-stemmed wheats released in different eras. The progeny derived from different crosses between solid and hollow parents was evaluated to determine the genetic basis for improved yield in modern solid-stemmed spring wheats. Space-planted nurseries of different crosses grown in 1990 and 1991 showed that the genetic basis of stem solidness is different between an early release (Rescue) and a later release (Lew) Additionally, larger experiments of F6 progeny derived from crosses between solid and hollow parents were grown in two different environments and agronomic data were gathered. The genetic correlation coefficients between stem solidness and grain yield were small and did not tend to be negative. Therefore, no negative genetic relationship appears to exist between stem solidness and grain yield. However, stem solidness was found negatively correlated to protein and plant height in early solid-stemmed releases. Thus, it appears that a linkage existed between the genes for solid stems and genes conferring poor percent protein and tall plants in the early releases. This linkage appears to have been broken in later releases. Stem solidness was independent of all other traits studied. Heritabilities of all traits, except yield, were high.Item Factors influencing the outcome of barley yellow streak mosaic virus-Petrobia latens-barley interactions(Montana State University - Bozeman, College of Agriculture, 1995) Smidansky, Eric DanielItem Evaluation of alternative crops for management of Pratylenchus neglectus in Montana winter wheat production(Montana State University - Bozeman, College of Agriculture, 2010) Zuck, Peter Christopher; Chairperson, Graduate Committee: Alan T. Dyer.A series of crop rotations were evaluated for their impacts on soil-borne populations of root lesion nematodes, Pratylenchus neglectus. Population changes, measured as the ratio of P. neglectus adults counted at harvest to those counted at planting time, was recorded under a series of two-year rotations alternating winter wheat with either fallow, barley, pea, lentil, canola, and camelina. Fallow, barley, pea, and camelina were found to have a neutral effect on nematode populations (p < 0.001). Winter wheat and canola caused significant increases in populations, while lentils caused significant decreases (p < 0.001). Populations were sustained through winter following winter wheat and barley, but not canola, camelina, pea, lentil, or fallow treatments (p < 0.001). In addition to the rotation study, cultivars of barley and canola were evaluated for their resistance to P. neglectus. Greenhouse trials for barley showed significant differences among 19 cultivars tested (p < 0.001), with a 5-fold difference in P. neglectus multiplication separating the least- from the most resistant. Separation among cultivars was not found with canola (p = 0.20). The information gathered in this study will help Montana wheat growers better understand the impacts of their crop selections on this important pest.Item The pathogenicity of Fusarium spp. to Wheat Stem Sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae)(Montana State University - Bozeman, College of Agriculture, 2008) Sun, Zhitan; Chairperson, Graduate Committee: David K. WeaverThe wheat stem sawfly is the most destructive insect pest in both winter wheat and spring wheat production in the northern Great Plains. The sawfly is univoltine, and spends all immature stages within protective wheat stems, which explains the difficulty in controlling populations. However, the almost continuous inhabitation of stems also makes larvae more vulnerable to invasion by microorganisms colonizing both living stems and postharvest stubble. Fusarium spp. were frequently isolated from fungalcolonized larval cadavers, and were found to be the major lethal factors for overwintering larvae in both laboratory emergence experiments and field surveys over three years. The pathogenicity of single isolates of three Fusarium spp., including F. pseudograminearum, F. culmorum, and F. acuminatum, was evaluated against overwintering larvae in sawflycut stems and against actively-feeding larvae in growing winter wheat plants over two years. The tested Fusarium isolates caused twenty to sixty percent mortality in overwintering larvae, and caused forty to eighty percent mortality in actively-feeding larvae. The Fusarium isolates also caused decomposition of sawfly-cut stems and disease in wheat plants, which reflected the versatility of Fusarium isolates acting as saprophytes, entomopathogens, and phytopathogens. Deoxynivalenol was detected in wheat stem tissues colonized by the Fusarium isolates from two years of field experiments, and deoxynivalenol caused toxicity and inhibited the growth of second and third-instar actively-feeding larvae in laboratory bioassays. Wheat grower observations of greater sawfly infestation in dryland wheat fields led to assessment of larval mortality from Fusarium infection in both dryland and irrigated wheat fields. This was studied using cage experiments or field surveys at different locations for three years. Parasitoid attack and fungal infection, mainly by Fusarium spp., were found to be the major lethal factors for developing and overwintering larvae, respectively. There was no difference in sawfly survival in dryland or irrigated wheat fields. As ubiquitous soil microorganisms and plant pathogens, Fusarium spp. impact wheat stem sawfly populations in the field each year.Item Discovery and distribution of root lesion nematode, Pratylenchus neglectus, in Montana(Montana State University - Bozeman, College of Agriculture, 2007) Johnson, Wendy Ann; Chairperson, Graduate Committee: Alan T. Dyer.Root lesion nematodes (Pratylenchus neglectus and P. thornei) cause significant yield losses for wheat worldwide. To assess the prevalence of root lesion nematodes in Montana, soil samples were collected statewide in 2006 and 2007. In 2006, P. neglectus was found in 12 of the 17 counties and in 41% of all field samples surveyed. In 2007, P. neglectus was found in 11 of 15 counties and in 37% of all field samples surveyed. No P. thornei was found. For fields having root lesion nematode in 2006, P. neglectus mean population densities were 1213 nematodes/kg soil with population densities exceeding the damage threshold of 2500 nematodes/kg soil in 14% of the sampled fields. For fields having root lesion nematodes in 2007, P. neglectus mean population densities were 1303 nematodes/kg dry soil with densities exceeding the damage threshold of 2500 nematodes/kg dry soil in 13% of the samples. Damaging populations were restricted to the north central part of the state and were generally found in fields following a crop of winter wheat (p= 0.02). Stunt nematodes (Tylenchorynchus spp.) were detected in 93% and 85% of sampled fields for 2006 and 2007, respectively.