Soybean aphid, Aphis glycines Matsumura, is an important pest of North American soybean. This dissertation identifies and addresses knowledge gaps, and integrates existing knowledge regarding distribution and abundance of this species. Early summer soybean colonization patterns by A. glycines were examined relative to landscape parameters, including density of overwintering hosts (buckthorn). An information-theoretic model selection approach was used to determine which landscape parameters were most influential in the distribution of colonizing aphids. Though buckthorn abundance best explained aphid colonization and population density, a density-dependent effect was observed. When aphid populations were low, more aphids were found in the vicinity of buckthorn, when aphid populations were higher, more aphids were found farther from buckthorn. Suction trap captures of migrating populations of A. glycines from 2005-2009 from a suction trap network covering much of central North America were examined. A model selection approach was used to determine the environmental triggers of summer and fall aphid flights, and spatial analysis and modeled wind trajectories were used to examine patterns in the abundance of alates. Two alate activity peaks were observed in fall. In summer, formation of alates was a function of field infestation. A tritrophic population model was built using DYMEX, a mechanistic lifecycle based modeling software package. The model incorporated soybean, A. glycines, and three natural enemy species, interacting based on phenological, physiological and functional response data available in the literature. The model was validated using Ontario field data, and several simulations were performed and are discussed. An evaluation of proposed control strategies for efficacy and impact on natural enemies and the environment was conducted. Two novel concepts are presented: the natural enemy unit, a standardization of the impact of predator guild on prey populations by the number of prey an individual predator can eat, and the selectivity index, where the selectivity of a pesticide is a function of the change in ratio of natural enemy units to prey before and after treatment. The selectivity index was inversely correlated with the Environmental Impact Quotient (EIQ), a theoretical measure of impact, validating EIQ's field applicability. / Natural Sciences and Engineering Research Council of Canada; The Keefer family trust; the Mary Edmunds Williams trust, the family of Fred W. Presant, and the University of Guelph provided scholarship and fellowship funds. Research was funded by a grant to Rebecca Hallett and Art Schaafsma from the Agriculture and Agri-Food Canada Pest Management Centre’s Pesticide Risk Reduction Program.

Commodity projection studies anticipate an exponential increase in copper demand and decreasein mill grade of deposits currently exploited globally. Most of this demand is driven by theindispensable use of copper in electrification and currently, the growing demand in the contextof the green transition. To meet this challenge while supplying society with copper, producerssuch as Boliden AB have plans for exploration and expansion projects to increase their reservesand in turn increase production through efficient measures. As grinding is a bottleneck to mineralprocessing and the most energy intensive, more efficient comminution systems are beingconsidered for environmental sustainability. These are required to have lower energyconsumption while achieving the required liberation or better for subsequent processing byflotation. Consequently, the literature review shows there is a research query on whether more can beexpected from comminution to optimise for downstream processing. With most publishedresearch being on particles with a P80 less than 100 μm, there exists a gap in investigating theeffect of grinding on flotation for coarser size fractions which this degree project focuses on.Importantly, it includes evaluating chalcopyrite liberation and flotation performance when usinga Novel Comminution Device. Three grinding mills were considered, a vertical roller mill (VRM),a Novel Comminution Device (NCD), with a rod mill as the reference mill. The scope of this studywas an analysis of the mill products’ particle size distribution, chalcopyrite liberation andinvestigation of the flotation performance of the products from the three mills. This was done ona Cu-Au-Ag ore from the Boliden Aitik mine in northern Sweden. Particle size distribution (PSD) analysis revealed that at comparable P80 values, the VRMproduced particles had broader PSD curves than the rod mill, while the NCD provided a steeperproduct size distribution than its reference rod mill products. The chalcopyrite liberation analysisusing QEMSCAN automated mineralogy showed that for samples split into three size fractions, -45 μm, +45/-90 μm and +90 μm, the VRM and rod mill products had their highest proportion offree to liberated particles within the intermediate size fraction while for the NCD sample this waswithin the fine fraction. Overall, the NCD product had the highest free to liberated particles acrossall fractions. From shape analysis based on scanning electron microscopy (SEM) images, it wasobserved that the NCD produced particles with the higher elongation than the VRM and rod mill. The flotation performance was assessed with respect to the mass pull, kinetics, grade andrecovery in the concentrate and separation efficiency. The rougher batch flotation tests indicatedthat flotation of the VRM ground samples had higher mass pull, Cu recovery, faster kinetics andlower Cu grade than the samples from the reference rod mill. This was also a similar outcome forthe NCD with the exception of higher mass pull at an increased collector dosage in the rod millcase. For all the mills, the general trend showed that an increase in P80 was associated withreduced mass pull. Overall, at similar flotation conditions, despite having one of the coarsest P80s,the NCD product showed the fastest Cu recovery kinetics, highest total recovery and selectivityindex. The rod mill reference test samples gave the highest grade but the lowest recovery. The findings illustrate that there is a significant difference in PSD broadness between productsfrom different mills at comparable P80. The differences in flotation performance between thethree mill products were mainly attributed to differences in liberation, potential differences insurface activation between wet and dry grinding methods and to some extent, steepness of thePSD curve. Based on the high recovery yet low grade of the NCD ground product, this is best suitedfor the rougher flotation stage. Future studies should therefore include cleaner stage flotation andoptimisation tests for the NCD with respect to reagent dosages and hydrodynamic conditions.

Malaria, caused by the parasite Plasmodium falciparum, has a long history as a global health threat. The vector-borne disease causes millions of deaths yearly, especially in developing countries with tropical climates that facilitate transmission. Compounding the problem is the emergence of drug-resistant strains due to overuse of outdated treatments. New compounds with antiplasmodial activity are needed to be developed as effective drugs against malaria. The hypothesis for this project is that marine microorganisms have a high likelihood of yielding novel antiplasmodial chemotypes because of their high diversity, which has not yet been explored for antimalarial development. In this project, microbes harvested and fermented by the Harbor Branch Oceanographic Institute in Fort Pierce, Florida were explored as sources for antiplasmodial natural products. Using a SYBR Green I fluorescence-based assay, 1,000 microbial extracts were screened for inhibition of the multidrug-resistant Plasmodium falciparum strain Dd2. Dose-response analysis was performed on 46 fractions from isolates whose extracts demonstrated greater-than or equal to] 70% inhibition of Dd2 at 1 micro]g/mL. To evaluate cytotoxicity, the MTS cell viability assay was used to calculate IC50 of extracts from active isolates in NIH/3T3 embryonic mouse fibroblasts. Several extracts demonstrated low IC50 in Dd2 and high IC50 in 3T3, suggesting that they contain potential lead antimalarial compounds. Extracts with high selectivity indices (potent plasmodial inhibition with low mammalian toxicity) have been prioritized for dereplication, with the goal of identifying novel active components that can be developed as antimalarial drugs.