Theses and Dissertations at Montana State University (MSU)
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Item Integrated pest management plan for the sevilleta national wildlife refuge(Montana State University, 2021) Sprigg, Edward Wilmans; Chairperson, Graduate Committee: Jane M. MangoldEach National Wildlife Refuge (NWR) within the U.S. Fish and Wildlife Service (FWS) National Wildlife Refuge System provides landscapes that contribute to conservation of wildlife and the habitats they depend on at local, regional, and national levels. I am the New Mexico Invasive Species Strike Team Lead and am responsible for planning and management of invasive species on eight National Wildlife Refuges across the state. Part of my responsibilities included writing Integrated Pest Management Plans. My Professional Paper, the Integrated Pest Management Plan (IPMP) for Sevilleta National Wildlife Refuges presents the goals, objectives, strategies, and guidance for managing non-native invasive species, as well addresses the long-term vision, continuity, and consistency for the target species on Sevilleta NWR. My IPMP identifies the highest priority non-native invasive plant species found on the Refuge as well as prioritizes areas for treatment. I selected areas based on the conservation assets of Sevilleta NWR and then identified the invasive species that occur in these areas. I combined two tools produced by the FWS for prioritizing target areas and species. The Invasive Plant Inventory and Early Detection Tool (IPIEDT) focuses on Early Detection Rapid Response and the Invasive Plant Management and Prioritization Tool (IPMPT) prioritizes based on response to management actions. By combining the tools, I added the management aspect from the IPMPT to the inventory and rapid response portion of the IPIEDT to encourage more active management of early detection rapid response species. Without prioritization, management objectives can be subjected to personal bias and lack long term success. I established management objectives and yearly actions to meet these objectives. Regular monitoring is required to ensure management is effective and moving towards achieving the objectives. A specific monitoring protocol was not developed as a part of my plan. Ideally, this would have been included, but Refuge staff are unlikely to enact any formal monitoring due to low staffing. My plan will also guide priority work for the New Mexico Invasive Species Strike Team and its funds and is intended to be adaptable to changing circumstances and remain in effect until the objectives are met.Item Tritrophic responses to signaling formulations sprayed in wheat stem sawfly-infested field plots(Montana State University - Bozeman, College of Agriculture, 2019) Caron, Christopher G.; Chairperson, Graduate Committee: Scott PowellThe wheat stem sawfly (Cephus cinctus Norton) is an economically important pest of wheat in the Northern Great Plains of North America. Producers and researchers are continuing to search for an effective management strategy. A combination of management tactics, such as host-plant resistance and biocontrol, may be the best method to suppress wheat stem sawfly (WSS) populations. My study examines whether direct toxicity, induced host-plant resistance, or the manipulation of tritrophic interactions, can be achieved through the application of signaling molecules in WSS-infested plots. The overall objective was to assess whether signaling molecules could be incorporated as a management tactic for WSS. Field experiments assessed whether aqueous applications of methyl jasmonate (MeJA), methyl salicylate (MeSA), and Actigard? influence WSS fitness, host-plant fitness, or the recruitment of natural enemies. Treatments were applied in WSS-infested plots for 3 consecutive weeks in both 2017 and in a second experiment in 2018. Wheat samples were collected before harvest and processed to assess parameters of infestation and parasitism. Plant growth and yield parameters were also recorded. The field trials suggested that MeJA and Actigard? induced significant changes that can impact tritrophic interactions in winter wheat. No effect was observed from the applications of MeSA. WSS fitness parameters decreased with applications of MeJA. MeJA treated plots had decreased infestation (2017), decreased larval weight (2018), and increased neonate mortality (2018). Actigard? treated plots had decreased larval weight and increased recruitment of clerid beetles (Phyllobaenus dubius Wolcott) (2017). Treatments of MeJA decreased stem height and grain weight, while treatments of Actigard? decreased grain weight in 2017. Although many of these findings were not consistent for both growing seasons, this study demonstrates the potential for these signaling molecules to manipulate the interactions between the WSS, or its host plant, and associated natural enemies in winter wheat.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 Evaluating host plant preference and pheromone attract and kill as strategies to manage pea leaf weevil Sitona lineatus (L.) (Coleoptera: Curculionidae) in Montana(Montana State University - Bozeman, College of Agriculture, 2022) Kiju, Pragya; Chairperson, Graduate Committee: Michael A. Ivie and Kevin Wanner (co-chair); This is a manuscript style paper that includes co-authored chapters.Pea leaf weevil (Sitona lineatus) is the most common insect pest of field peas grown in Montana. Montana is the number one producer of field pea in the US. Currently, Montana producers spray insecticides at least once or twice during the spring growing season to avoid leaf damage inflicted by pea leaf weevil adults and larvae. Complete reliance on insecticides may, however, raise the risk of pea leaf weevil populations developing genetic resistance. Therefore, this project focuses on development of alternative pulse insect pest management strategies such as pheromone-based attract and kill and host plant preference. For the attract and kill strategy 6 different treatments compared combinations of aggregate pheromone (4-methyal-3,5- heptanedione) alone in two different forms; septa and pellet, pheromone with granular insecticide (Deltamethrin). To determine the effect of host variety on adult feeding preference, 10 field pea, 2 faba bean, 2 lentil and 2 chickpea varieties were assessed for feeding damage. Crescent shaped notches were counted on 10 individual plants per replicate plot. The average number of larvae within the nitrogen fixing root nodules of each variety was also recorded on 5 randomly selected individual plants per plot. Faba bean was the most preferred host while lentil and chickpea suffered almost no feeding damage. 'Delta' and 'Lifter' field pea varieties appeared to be preferred over 'DS Admiral' and 'AC Agassiz' varieties. Given the significant level of feeding on all pea and faba bean cultivars further evaluation of low-cost pheromone traps are essential to establishing an IPM control approach.