We work mostly with plants and insects, and our projects are united by a focus on how land-use and land-cover change influence biodiversity and ecosystem function. Most of our research is field- and lab/greenhouse-based, but we also incorporate modeling (GIS, model fitting, simulations) and analytical (stable isotope and DNA sequencing) approaches into our research. Our research links empirically-derived data with basic ecological theory and we use this basic knowledge to better manage insects and plants for restoration and sustainable agriculture. Below is some information about our current projects.
1. Plant-insect interactions across spatial scales
Environmental variability can affect the strength of plant-insect interactions yet it is unclear how these patterns should change with spatial scale. We have worked on several NSF, USDA, and DOE funded projects examining how environmental variability influences plant-insect interactions at different spatial scales. At very small spatial scales (< 2 m2), environmental variability due to plant neighborhood composition influences damage to plants (Kim and Underwood 2015) through variability in herbivore growth, host-plant selection, and feeding behavior (Kim 2017). At medium spatial scales (i.e., landscape scale), environmental variability due landscape composition influences the strength of tri-trophic interactions between plants, insect herbivores, and arthropod predators (Liere, Kim, et al. 2014, Kim et al. 2017, Kim et al. 2018) by affecting the regional species pool of arthropods and prey-tracking ability of predators for prey. Finally, at very large spatial scales (i.e., continent scale), environmental variability due to location along a latitudinal gradient influences plant damage and resistance which were likely driven by differences in herbivore community structure, range, and distribution (Kim, 2014). Altogether these studies suggest that environmental factors affecting insect feeding behavior and their distribution can influence the strength of plant-insect interactions across multiple scales. Understanding how the strength of plant-insect interactions varies across spatial gradients has implications for predicting how disturbances such as land-use change or climate change might impact plant communities through their effects on insect herbivores (Kim et al. 2013).
2. Disturbance effects on biodiversity
Natural and anthropogenic disturbances can influence biodiversity and ecosystem function. Because disturbances can occur at both localized and landscape scales, it is unclear whether these disturbances can have additive or multiplicative effects for plant and insect communities. In Wisconsin, we examined how annual harvesting of perennial grasslands (a localized disturbance) affected predatory arthropod communities and the ecological functions they perform (natural biological control). We also examined whether land-use change (a landscape-scale disturbance) could accentuate or mitigate the potentially negative effects of disturbance for arthropod communities. We found that annual harvesting of perennial grasslands and land-use change had variable effects on the abundances of different functional groups (Kim et al. 2017), alpha and beta diversity (Kim et al. 2018), and predator diet breadth (Kim et al. 2019). Despite these changes in predator community structure and feeding behavior, there were no harvest effects on pest suppression services suggesting compensation in pest suppression function by unaffected arthropod groups. These results suggest that disturbances occurring at different spatial scales (localized versus landscape scales) can interact with one another to have unpredictable, non-additive effects on arthropod biodiversity and ecosystem function.
In Kansas, we are looking at the direct and indirect effects of bison grazing and fire on beneficial insects such as pollinators and natural enemies through their effects on the plant communities, ground cover, and the physical structure of the soil. Stay tuned for updates on this project!
3. Spatio-temporal effects of resource availability on insect population dynamics
We are investigating the relative importance of spatial and temporal heterogeneity in resource availability on population dynamics of consumers. Landscape theory has focused mainly on how the spatial arrangement of patches (i.e., amount and configuration) affect population dynamics of consumers but the importance of temporal variability in resource availability has been largely overlooked. Using three approaches, we are examining how the spatio-temporal availability of food resources affects mobile consumer populations. (1) In a field study in WI, we are examining how the phenology of prey resources affects the physiology and performance of predatory insects such as lady beetles and ecosystem function (e.g. prey consumption rates). (2) Using a controlled lab feeding experiment, we are investigating how temporal variability in prey type and amount influence the fitness and behavior of lady beetles, and (3) using a lab microcosm with bean beetles (Callosobruchus maculatus), we are testing how the spatial arrangement and timing of available resources affect populations dynamics of consumers. Bean beetles are ideal organisms to test theories in landscape ecology because they are easy to rear in the lab, landscape configurations are easy to manipulate, and generation times are relatively short (30 days from egg to adult). Because of the inherent difficulties of manipulating entire landscapes, factors such as resource amount and arrangement are often confounded. This lab approach will allow us to disentangle the relative importance of food resource timing and spatial arrangement on consumer populations.
4. Benefits of conservation strips for biological control
Chemical insecticides are a widely used component of pest management in field crops however, many insecticides can have unintended non-target effects on beneficial organisms such as natural enemies, pollinators, and resistance to insecticides is an ever-present concern that can severely limit their effectiveness in the long run. One way to mitigate the negative impact of insecticides on wildlife and humans is through the use of conservation border strips to improve ecosystem services such as pollination, pest suppression, and water quality. I am interested the economic and ecological benefits of border strips for pest management and how insects (both beneficial and harmful) move across border boundaries.