"In recent years, our understanding of predator-prey interactions has grown in recognizing that predators can affect prey species both through consumptive and non-consumptive effects. While consumptive effects result in direct consumption of a prey species, non-consumptive effects result in a behavioral or physiological prey response to predation threat, and may have an overall larger impact on prey success than predator consumptive effects. Additionally, there is a gap in our understanding of how habitat management practices, such as cover crop mulches or nutrient management, might influence these interactions. My research aims to fill these knowledge gaps by 1) determining the impact of habitat, host plant, and predator cues, alone and in combination, on P. rapae oviposition in greenhouse choice tests and field observations; 2) investigate how top-down (predator) cues and bottom-up (plant) cues interact to influence P. rapae adult and larval behavior; 3) determine consumptive and non-consumptive effects of different predator species, alone and in combination, on P. rapae; 4) investigate how habitat management practices influence predator -- prey interactions; 5) identify habitat domains of three common natural enemies and how their interaction might alter these domains; 6) and determine how habitat management practices influence wild natural enemy abundance. Oviposition preference of P. rapae was observed in greenhouse choice tests in 2015-2017 and in field observations in 2016 to determine the impacts of plant size, habitat structure, plant nitrogen, and predator cues on host plant choice. In both greenhouse and field experiments, P. rapae preferred plants that were large in size compared to small plants, and plants without added habitat structure (no plastic leaves or cover crop mulch). Plant size and nitrogen had a synergistic effect on host plant choice, with large high nitrogen plants accruing more eggs than either cue alone. Predator cues had no significant effect on oviposition. Single predator species consumptive and non-consumptive effects were measured in environmental chamber bioassays in 2017-2018 and in field experiments in 2016-2018. Adult and larval P. rapae altered their preference for bottom-up factors (plant nitrogen) under predation threats from differing predator species, preferring high nitrogen plants when threatened by Hippodamia convergens, but not Podisus maculiventris. Additionally, larvae consumed more leaf tissue and grew larger when threatened by H. convergens, but leaf tissue consumption and larval growth did not change under threat by P. maculiventris, suggesting that larvae may change their behavior if they are able to quickly outgrow life stages vulnerable to predation. Multiple species assemblage consumptive and non-consumptive effects on P. rapae were observed in environmental chamber bioassays in 2016 and in field experiments in 2016-2017. Predator habitat domains were measured in 2017, and a wild natural enemy analysis was performed in the field in 2017. Hippodamia convergens present with P. maculiventris had the highest level of control on P. rapae larvae. Lycosidae negatively impacted P. rapae consumption in almost all predator assemblages, and both H. convergens and P. maculiventris altered their behavior when present in cages with Lycosidae. Habitat management in field experiments did not impact predator effects; however, habitat management in field plots did influence abundance of some natural enemies. Overall, the results of this research provide a deeper understanding of the effects of habitat management and predator species identity on predator consumptive and non-consumptive effects on P. rapae, and have implications for cole crop growers who may want to utilize habitat management strategies to aid in P. rapae pest management."--Pages ii-iii.
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