Theses and Dissertations at Montana State University (MSU)

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Population dynamics of wheat stem sawfly, Cephus cinctus Norton, in barley in Montana
(Montana State University - Bozeman, College of Agriculture, 2020) Achhami, Buddhi Bahadur; Chairperson, Graduate Committee: David K. Weaver; Gadi V. P. Reddy, Jamie D. Sherman, Robert K. D. Peterson and David K. Weaver were co-authors of the article, 'Antixenosis, antibiosis, and potential yield compensatory responses in barley cultivars exposed to wheat stem sawfly under field conditions' which is contained within this dissertation.; Gadi V. P. Reddy, Jamie D. Sherman, Robert K. D. Peterson and David K. Weaver were co-authors of the article, 'Effect of precipitation and temperature on larval survival of Cephus cinctus (Hymenoptera: Cephidae) in barley cultivars' which is contained within this dissertation.; Robert K. D. Peterson, Jamie D. Sherman, Gadi V. P. Reddy and David K. Weaver were co-authors of the article, 'Multiple decrement life tables of Cephus cinctus Norton (Hymenoptera: Cephidae) across a set of barley cultivars: the importance of plant defense versus cannibalism' which is contained within this dissertation.; Gadi V. P. Reddy, Megan L. Hofland, Robert K. D. Peterson, Jamie D. Sherman and David K. Weaver were co-authors of the article, 'Host selection and oviposition behaviors of Cephus cinctus (Hymenoptera: Cephidae) in barley' which is contained within this dissertation.
Wheat stem sawfly (WSS) is an economically devastating pest of cereals grown in North America. The larva is the only feeding stage and remains confined within a host stem until it emerges as an adult the following year. This limited mobility increases larval vulnerability to mortality factors when host plant traits are hostile to survival. For instance, larval mortality is greater in barley than in solid stemmed wheat cultivars known to be resistant. Both solid stemmed wheat and barley kill neonates via host plant resistance traits. Traditionally, barley was recommended as an alternative rotational crop to prevent WSS outbreaks in wheat crops. There is limited data available regarding barley host plant resistance and questions persist. Has barley resistance changed over time? What is the impact of larval feeding injury on grain yield of barley? Do females display similar oviposition behaviors across barley cultivars that vary in susceptibility? To answer these questions. I conducted field experiments to assess resistance and possible tolerance to WSS in eight barley cultivars. Based on the number of eggs, 'Hockett' was the most attractive cultivar to WSS female (less antixenosis), while 'Craft' and 'Celebration' killed the greatest number of neonates due to antibiosis. Multiple decrement life table studies revealed that plant defense and cannibalism were two major causes of larval mortality. We measured greater yield in infested stems with dead larvae (potential tolerance) than for cut stems and both were greater than uninfested stems in all cultivars except 'Celebration'. A greenhouse study revealed that females preferred 'Hockett' over 'Craft' in frequencies of oviposition behaviors and numbers of eggs deposited. Additionally, a greater amount of the WSS attractant (Z)-3-hexenyl acetate was found in aerations from 'Hockett' plants than from 'Craft.' The amount of defensive compound linalool was greater in aerations from 'Craft' than from 'Hockett.' These results suggest that barley cultivars are equipped with varying levels of antibiosis, antixenosis, and tolerance traits against WSS. Thus, we can exploit these traits in the development of cultivars which can reduce WSS populations and decrease economic loss caused by this species.
Evaluation of wheat production practices under wheat streak mosaic disease risk and wheat stem sawfly pressure in Montana
(Montana State University - Bozeman, College of Agriculture, 2020) McKelvy, Uta; Chairperson, Graduate Committee: Mary Burrows; Monica Brelsford, Jamie Sherman and Mary Burrows were co-authors of the article, 'Susceptibility and tolerance of winter wheat, spring wheat and barley cultivars to mechanical inoculation with wheat streak mosaic virus' submitted to the journal 'Plant health progress' which is contained within this dissertation.; Peggy Lamb, Monica Brelsford and Mary Burrows were co-authors of the article, 'Impact of planting date, seeding rate and cultivar choice on spring and winter wheat productivity and profitability in Montana' submitted to the journal 'Agronomy journal' which is contained within this dissertation.; David Weaver and Mary Burrows were co-authors of the article, 'Evaluation of chemical and cultural management practices for wheat stem sawfly control and effects on beneficial insects in spring wheat in Montana' submitted to the journal 'Journal of economic entomology' which is contained within this dissertation.
Wheat (Triticum aestivum L.) is an economically important crop for Montana's agricultural industry. Wheat streak mosaic (WSM) is an important viral disease in Montana and the wheat stem sawfly (WSS; Cephus cinctus Norton) is a major insect pest in the state. Understanding these disease and pest problems and the factors that promote and suppress disease and pest pressure forms the foundation for a successful integrated pest management program. In this dissertation, we evaluate wheat production practices in Montana and provide information on the effectiveness and implications of cultural and chemical management practices in mitigating WSM disease and WSS pressure. We assessed the tolerance of popular winter wheat, spring wheat, and barley cultivars in Montana to mechanical inoculation with WSMV in field studies. Winter wheat 'Brawl CL Plus' and breeding lines CO12D922 and MTV1681 demonstrated moderate WSMV incidence and minor yield penalties under WSMV inoculation, making them suitable cultivars to be grown in high-risk environments. We investigated the effects of cultivar choice, planting date, and seeding rate on grain yield and quality parameters in field studies. Our results validated current planting date recommendations for Montana. Yield reductions were observed at planting dates later than mid-September and April for winter wheat and spring wheat, respectively. No yield increase was observed when winter wheat was planted before mid-September. No meaningful and reliable economic benefits were associated with an increase in seeding rate beyond the recommended density. We developed a WSM risk prediction model and released it as the online learning tool AWaRe ('Assessment of Wheat streak mosaic Risk'). AWaRe presents the first learning tool that integrates complex information on the dynamics underlying WSM disease and relates them to the user in an interactive way. We expect the adoption of risk assessment based WSM management practices that result in a reduced economic impact through the use of this tool. The potential of different insecticides to manage WSS damage was compared to spring wheat genotypes with varying degrees of WSS resistance. Results showed that application of the systemic insecticide Thimet-20G provided effective protection of susceptible cultivar 'Reeder,' but use of solid-stem cultivars were similarly effective.
Effect of agronomic practices on disease incidence, severity, and impacts in Montana cropping systems
(Montana State University - Bozeman, College of Agriculture, 2017) Ranabhat, Nar Bahadur; Chairperson, Graduate Committee: Fabian D. Menalled; Mary Burrows (co-chair)
Integrated pest management is at the foundation of sustainable cropping systems. This thesis investigated 1) the influence of alternative host plants and agronomic practices on Wheat streak mosaic virus (WSMV) risk, and 2) how cover crop termination methods influence diseases in grazed organic, tilled organic, and chemical no-till systems. To assess the influence of alternative hosts including volunteer wheat, Bromus tectorum, Setaria viridis, and Zea mays on WSMV incidence and its vector, the wheat curl mite (Aceria tosichella, WCM) movement during the fall, a 'trap plant' capture system was used. In 2013, alternative hosts had similar WCM infestation levels compared to the control in most weeks. In 2014, spring planted B. tectorum and volunteer wheat increased the incidence of WSMV and abundance of WCM compared to control. In a study assessing the impact of planting date and winter wheat variety on WSMV incidence, there was almost no infection of WSMV across resistant wheat varieties. However, Pronghorn, a susceptible wheat variety, had a higher WSMV incidence at the early planting date than recommended and late planting dates. In a companion study of the impact of wheat variety and timing of N application on WSMV incidence, results did not differ across N application timing across resistant varieties. However, early spring N application in 2014 had a higher WSMV incidence compared to fall and late spring N application in Pronghorn and Yellowstone. A study assessing the impact of cropping systems on diseases indicated that disease incidence during the transition to organic period in 2013 and 2014 as well as an established organic year, 2016, was similar at tillering and flowering stages of winter wheat between the grazed organic, tilled organic, and chemical no till system. However, disease incidence was variable between systems at the matured growth stage in 2014 and 2016. In 2015, disease incidence varied between systems at all growth stages. Overall, disease severity was similar in winter wheat between grazed organic, tilled organic, and chemical no till systems, indicating disease is not a major constraint to organic methods of crop production during the transition period.
Exposure and risk to non-target receptors for agricultural spray drift of formulation types and adjuvants
(Montana State University - Bozeman, College of Agriculture, 2017) Preftakes, Collin James; Chairperson, Graduate Committee: Robert K. D. Peterson; Jerome J. Schleier III, David K. Weaver, Greg Kruger, Ryan Henry and Robert K. D. Peterson were co-authors of the article, 'Effect of insecticide formulation and adjuvant combination on agricultural spray drift' which is contained within this thesis.; Jerome J. Schleier III, David K. Weaver and Robert K. D. Peterson were co-authors of the article, 'Non-target insect risk assessment of drift reduction insecticide formulations and spray adjuvants' which is contained within this thesis.
Agricultural applications of crop protection products can have negative economic and ecological consequences when spray drift occurs. Among the ways to reduce spray drift is to manipulate the physical properties of the spray solution with formulated products and tank additives, but further research is required to better understand their effects. By measuring spray drift under field conditions and using the results to estimate ecological risk, we characterize the effect on drift for two formulation types and two adjuvants. A field study was conducted where off-target ground deposition and droplet size were measured to indicate spray drift for different combinations of the formulations and adjuvants, accounting for environmental conditions. Each treatment combination was also sprayed in a wind tunnel set up to precisely measure droplet spectra so that these could be related to deposition in the field. Finally, an efficacy experiment was conducted to test for tradeoffs between drift reduction and pest control. Results from the field study suggest that as much as 32% drift reduction was achieved by selecting between the tested formulation types, and as much as 62% by incorporating certain spray adjuvants, but this effect depended on the formulation/adjuvant combination. Treatments with smaller droplet sizes had greater drift, and there was no tradeoff between drift reduction and pest control. We assessed ecological risk for terrestrial insects in non-target habitats using a novel approach to estimate insecticide residue on plant surfaces based on ground deposition data from the field study. Exposure concentrations were combined with a cumulative distribution of species sensitivities to statistically represent the risk of toxicity for the active ingredient that was used and the levels of drift that were observed. We found that substantial reductions in the percentage of insect species affected in an off-target area could be achieved by certain formulation types and adjuvants. This work could be useful for developing a classification scheme for formulated products and tank additives based on their potential for reducing spray drift and ecological risk to non-target receptors.
Toxicity, exposure, and risk of insecticides used for mosquito management on the alfalfa leafcutting bee, Megachile rotundata
(Montana State University - Bozeman, College of Agriculture, 2017) Piccolomini, Alyssa Margaret; Chairperson, Graduate Committee: Robert K. D. Peterson; Shavonn R. Whiten, Michelle L. Flenniken, Kevin M. O'Neill and Robert K. D. Peterson were co-authors of the article, 'Acute toxicity of permethrin, deltamethrin, and etofenprox to the alfalfa leafcutting bee, Megachile rotundata (Hymenoptera: Megachilidae)' which is contained within this thesis.; Michelle L. Flenniken, Kevin M. O'Neill and Robert K. D. Peterson were co-authors of the article, 'Leaf residue toxicity and risk of mosquito insecticides to the bees, Megachile rotundata and Apis mellifera' which is contained within this thesis.; Michelle L. Flenniken, Kevin M. O'Neill, Ruth P. O'Neill, Casey M. Delphia and Robert K. D. Peterson were co-authors of the article, 'The effects of an ultra-low-volume application of etofenprox for mosquito management on Megachile rotundata (Hymenoptera: Megachilidae) larvae and adults in an agricultural setting' which is contained within this thesis.
The alfalfa leafcutting bee, Megachile rotundata F. (Hymenoptera: Megachilidae), is one of the most managed solitary bees and is an important pollinator of many crops, especially alfalfa, Medicago sativa L. However, little is known about its response to insecticides, specifically pyrethroids, which are frequently used to manage populations of adult mosquitoes that inhabit the same areas. Current regulatory requirements for insecticide toxicity to non-target insects focus on one pollinator, the honey bee, Apis mellifera L., but this species does not represent all insect pollinator species in terms of response to insecticides. Therefore, we characterized the toxicity and risk of three pyrethroid insecticides (permethrin, deltamethrin, and etofenprox) on adult M. rotundata in both laboratory and field settings. The median lethal dose, LD 50, was estimated for adult M. rotundata females when exposed to each pyrethroid to serve as a baseline toxicity test to determine the susceptibility of M. rotundata to these insecticides. The range of concentrations for permethrin and etofenprox ranged from 0.0075-0.076 microgram/bee and the range for deltamethrin was 0.0014-0.0075 microgram/bee. The estimated LD 50 results for permethrin, etofenprox, and deltamethrin were 0.057, 0.051, and 0.0016 microgram/bee, respectively. After obtaining the LD 50 values, we compared female respiration rates after dosing of each LD 50 endpoint. In a field study, we applied a formulated version of each active ingredient at the maximum labeled rate of 0.017 kg/ha over an alfalfa field via ultra-low-volume (ULV) applicator and observed mortality of both adult A. mellifera and M. rotundata for 48-hr after exposure. In both species, there was no significant difference in mortality between control and treated groups for any of the formulations. In another field study, a formulated version of etofenprox was applied in an alfalfa field at the half-maximum labeled rate of 0.003 kg/ha and directly targeted to M. rotundata nests. There was no significant difference in mortality between control and treated groups. We also did not observe a significant difference in the number of adults reared between treated vs. control shelters. Results from the field studies suggest that the risk of mortality from these insecticides applied via ULV applicators may be relatively low.
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 Burrows
Wheat 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.
Discovery and characterization of olfactory-related genes in the wheat stem sawfly, Cephus cinctus, a major pest of wheat in the northern plains
(Montana State University - Bozeman, College of Agriculture, 2014) Gress, Joanna Christine; Chairperson, Graduate Committee: Kevin Wanner; Hugh M. Robertson, David K. Weaver, Mensur Dlakic and Kevin W. Wanner were co-authors of the article, 'Odorant receptors of a primitive hymenopteran pest, the wheat stem sawfly' in the journal 'Insect molecular biology' which is contained within this thesis.; Hugh M. Robertson, Kim Walden and Kevin. W. Wanner were co-authors of the article, 'Olfactory-related genes annotated from the wheat stem sawfly, cephus cinctus' submitted to the journal 'Insect molecular biology' which is contained within this thesis.; Hugh M. Robertson, Kim Walden and Kevin W. Wanner were co-authors of the article, 'Annotation of the major chemosensory gene families in the wheat stem sawfly, Cephus cinctus, a major pest of wheat in the northern plains' submitted to the journal 'Insect molecular biology' which is contained within this thesis.; Charles C. Carey, Aurélien Mazurie and Kevin W. Wanner were co-authors of the article, 'Antennal expression of candidate olfactory-realted genes from the wheat stem sawfly, Cephus cinctus' submitted to the journal 'Insect molecular biology' which is contained within this thesis.
The wheat stem sawfly (WSS), Cephus cinctus (Hymenoptera: Cephidae), is one of the most important insect pests of wheat in the northern Great Plains region of the United States and Canada, with economic losses exceeding $100 million per year. Traditional pest management strategies including pesticides are generally unsuccessful due to an extended adult flight time and the inaccessible larval stage that feeds within the wheat stem. Research towards integrated pest management strategies based on olfaction has proved promising. However, little is known about the molecular basis of olfaction in this important insect pest. We have identified and annotated 131 members of the major olfactory-related gene families from antennal transcriptome and whole genome sequences, including: 6 odorant binding proteins (OBP), 8 chemosensory proteins (CSP), 53 odorant receptors (OR), 14 ionotropic receptors (IR), 12 carboxylesterases (CCE), 8 gluthatione S-transferases (GST), and 29 cytochrome P450s (P450). Expression levels in the antennae, sawfly bodies, and whole larvae were analyzed using RNA-seq. Gene expression results were used to identify candidate genes for further functional characterization based on higher enriched expression in antennae and/or sex-biased expression in the antennae. These candidate WSS olfactory genes may mediate important pest behaviors and serve as molecular targets for future insect management strategies.
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.
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 Aslam
The 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.
Evaluation of agronomic practices to reduce Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), damage in wheat
(Montana State University - Bozeman, College of Agriculture, 1992) Kammerzell, Kurt John

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