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Item Natal origin, migratory patterns, and abundance of the army cutworm moth, Euxoa auxiliaris(Montana State University - Bozeman, College of Agriculture, 2022) Dittemore, Clare Mikaela; Chairperson, Graduate Committee: Robert K. D. Peterson; This is a manuscript style paper that includes co-authored chapters.The army cutworm moth, Euxoa auxiliaris, is a migratory noctuid that migrates from and returns to the Great Plains. At their Rocky Mountain summering range, it is an important food for the Greater Yellowstone Ecosystem (GYE) grizzly bears, Ursus arctos horribilis. However, a limited understanding of moth migratory patterns, abundance at summering ranges, and the associated vulnerability and variability of these populations, is a shortfall in agency grizzly bear conservation strategies. Therefore, the objectives of our study were to assess the natal origin of moths collected from two mountain ranges and within the Great Plains, characterize larval feeding habits of migrants collected from the Absaroka Range, and assess a monitoring protocol to determine moth abundance at a GYE aggregation site. Using stable isotopes, we estimated the natal origin of migrants collected from the Absaroka and Lewis Ranges, examined migratory patterns within the Great Plains, and assessed the larval feeding habits of migrants collected in the Absaroka Range during 2017-2021. To estimate abundance, we sampled the airspace with a radar stationed within 1 km of an aggregation site in the GYE during 2020 and 2021. There was strong evidence that moths collected in the Great Plains and both mountain ranges were migrating north-south, in addition to previously established east-west movement. Although their origins were varied, moths of the Absaroka Range had the highest probability of origin in Alberta and British Columbia, and moderate probability in Montana, Idaho, and Wyoming across all collection years. Lewis Range moths had the highest probability of origin almost exclusively within the lower third of Canada. As larvae, the moths collected from the Absaroka Range fed almost exclusively on C3 plants. We estimate that 5 million moths passed through our radar's sampling plane (160-750 m above ground level and 2600 m across) over the course of 20 hours (5 nights of movement). Overall, our findings suggest that army cutworm moths at aggregation sites are 'supplied' by various source locations, and thus insulated against regional declines within their natal origins. Radar should be used at moth aggregation sites to continue monitoring army cutworm moths.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 Environmental drivers of salmonfly ecology in southwest Montana(Montana State University - Bozeman, College of Letters & Science, 2018) Anderson, Heidi Elise; Chairperson, Graduate Committee: Lindsey Albertson; Lindsey K. Albertson and David M. Walters were co-authors of the article, 'Temperature-driven range contraction and body size reduction of an iconic aquatic insect' submitted to the journal 'Freshwater science' which is contained within this thesis.; Lindsey K. Albertson and David M. Walters were co-authors of the article, 'Landscape features drive synchronicity of an aquatic insect resource pulse' submitted to the journal 'Ecological applications' which is contained within this thesis.Aquatic insects have ecological, cultural, and economic value throughout the American West. They can control the processing of in-stream nutrients, are a vital component of both aquatic and terrestrial food webs, and support economically important species such as trout and the eco-tourism industries structured around these fisheries. Salmonflies (Pteronarcys californica) are one of the most well-known aquatic insects in the American West due to their large size and popularity among fly-fishers. However, mounting anecdotal evidence suggests that salmonfly populations could be in decline. We conducted surveys and compiled historical datasets that quantified salmonfly abundance, body size, and emergence timing along the Gallatin and Madison Rivers in southwest Montana to determine the status of salmonfly populations in these rivers, understand environmental drivers that are constraining their distribution and driving their development, and initiate long-term monitoring. Most notably, we found evidence for temperature-driven changes in salmonfly distribution and body size along the Madison River in the last four decades and observed marked differences in salmonfly emergence phenology and duration at multiple spatial scales between the Madison and Gallatin Rivers. Above-optimal summer water temperatures appear to be the major constraint on salmonfly populations in the Madison River, but only play a minimal role in dictating salmonfly distribution along the Gallatin River. This research provides rare empirical evidence of long-term biological change of an aquatic insect and highlights the importance of combining temporal and spatial datasets to explicitly address species' responses to environmental stressors across multiple spatial and temporal scales. Freshwater habitats are increasingly imperiled by climate change and human-induced habitat alteration, which will invariably continue to impact the ecology of aquatic insects like salmonflies. This work contributes to the understanding of how these ongoing changes will influence the structure of aquatic communities, the flow and transfer of energy and nutrients, consumer-resource dynamics, and stream--riparian food web linkages.Item Seasonal and spatial patterns of mortality and sex ratio in the alfalfa leafcutting bee, Megachile rotundata (F.)(Montana State University - Bozeman, College of Agriculture, 2004) O'Neill, Ruth Pettinga; Chairperson, Graduate Committee: Sue Blodgett.Nests from five seed alfalfa sites of the alfalfa leafcutting bee Megachile rotundata (F.) were monitored over the duration of the nesting season in 2000 and 2001, from early July through late August. Cells containing progeny of known age and known position within the nest were subsequently analyzed for five commonly encountered categories of pre-diapause mortality in this species. Chalkbrood and pollen ball had the strongest seasonal relationships of mortality factors studied. Chalkbrood incidence was highest in early-produced cells. Pollen ball was higher in late-season cells. Chalkbrood, parasitism by the chalcid Pteromalus venustus, and death of older larvae and prepupae , due to unknown source(s) exhibited the strongest cell-position relationships. Both chalkbrood and parasitoid incidence were highest in the inner portions of nests. The “unknown” category of mortality was highest in outer portions of nests. Sex ratio was determined for a subset of progeny reared to adulthood. The ratio of females to males is highest in cells in inner nest positions. Sex ratio is female-biased very early in the nesting season, when all cells being provisioned are the inner cells of nests, due to the strong positional effect on sex ratio.Item Evaluation of sweep sampling as a method for determining grasshopper community composition on rangeland(Montana State University - Bozeman, College of Agriculture, 1996) Larson, Deanne PassaroItem The structure and performance of an adult population of Aulocara elliotti (Thomas) (Orthoptera, Acrididae) near Billings, Montana(Montana State University - Bozeman, College of Agriculture, 1972) Mussgnug, Gerald LouisItem The distribution and abundance of aquatic insects in the middle West Gallatin drainage(Montana State University - Bozeman, College of Agriculture, 1973) Garrett, Paul AllenItem Plecoptera of the West Fork of the West Gallatin River and factors influencing their distribution(Montana State University - Bozeman, College of Agriculture, 1973) Burns, David CharlesItem Aquatic insects in sediment traps(Montana State University - Bozeman, College of Agriculture, 1976) Mangels, Francis Wayne; Chairperson, Graduate Committee: George R. RoemhildSediment traps were set in three tributaries and in three areas of the upper Gallatin River. The kind, sizes and amount of sedimentation was analyzed and related to numbers and orders of aquatic insects found in gravel in the traps. From August, 1972, to October, 1973, samples were taken at monthly intervals in a monthly renewed sample and in a cumulative sample undisturbed since the beginning of the project. These sampling methods show that living space is of prime importance to aquatic insects and sculpins, and that it is a limiting factor for insect communities presently in the upper Gallatin. Measurable current speeds (up to 2.5 fps) did not seem to affect insect numbers. High percentages of organic matter in sediment coincided with high insect numbers, but actual weight had no apparent relationship. High numbers of insects were present in the spring, but were drastically reduced after runoff. They recovered much more slowly and to lower levels in the cumulative traps, which remained filled with sediment. The low sedimentation rates through fall and winter resulted in higher insect numbers in cumulative traps, presumably because they were undisturbed. Diptera was the dominant order in all areas.Item Sampling of grasshopper populations(Montana State University - Bozeman, College of Agriculture, 1948) York, George T.