Browsing by Subject "pollen"

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    Asthma Risk and the Co-occurrence of Thunderstorms and Elevated Pollen: Measuring the Strength of Association, Investigating the Effects in Subgroups, and Leveraging Data Across Large Areas.
    (2022-05) Smith, Morrison
    Abstract Severe asthma has been shown to occur in the combined presence of high pollen and thunderstorms, termed thunderstorm asthma. Previous research has focused on rare ‘epidemic’ events, such as in Melbourne, Australia 2016 where emergency room usage was 900% higher during a single thunderstorm asthma event. In my dissertation, we investigate thunderstorm asthma conditions in the Twin-Cities metro region, Minnesota, U.S.A., using detailed exposure estimates from a network of weather sensors along with daily pollen records, and asthma-related emergency department (ED) visits from 2007-2018. In manuscript 1, we investigate the association between asthma-related ED visits and thunderstorm asthma conditions within a study radius of 20 miles from the Minneapolis-St. Paul (MSP) airport using a time series model approach. We evaluated risk for the entire study area combined and at the individual zip code level to investigate potential effect heterogeneity and spatial auto-correlation. We find a 1.05 (95% CI: 1.012,1.083) times higher risk on the day of a thunderstorm asthma event with no evidence of spatial autocorrelation or effect heterogeneity. In manuscript 2, we investigate relative and absolute risk disparities of thunderstorm asthma by age and sex subpopulations. We find evidence that thunderstorm asthma has impacts across the life course for men and women, with variation in risk by individual age-sex groups contrary to typical baseline patterns of severe asthma incidence. For males 18-44 the RR of severe asthma was 1.123 times higher on storm days (95% CI: 1.042, 1.211) compared to non-storm days,] with 1.098 times higher risk of incident severe asthma on storm days for females over 45 (95% CI: 1.020, 1.181) compared to non-storm days. In manuscript 3, we investigate the ability to leverage exposure information from a single pollen site in MSP and land-use covariates to estimate thunderstorm asthma associations at 19 communities across the state of Minnesota. Using meta-regression, we find a positive association between deciduous tree and grassland land cover with the thunderstorm asthma effect size, and we find an attenuation of the thunderstorm asthma risk as distance increases from the MSP pollen site.
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    Effects of native prairie forbs on the foraging choices and recruitment behavior of honey bees (Apis mellifera)
    (2020-08) Carr-Markell, Morgan
    Recent increases in honey bee colony mortality have prompted many organizations to plant flowers to improve bee nutrition. However, there remain questions about which flower species to plant and how best to plant them. Honey bees and many non-native species of flowering plants arrived in North America with European colonists. To help restore diverse native species, many organizations would like to increase plantings of native flowers. In the Upper Midwest region, multiple organizations are working to reconstruct tallgrass prairie habitats, including native prairie forb species. However, it was unknown whether those species would attract and benefit honey bees. To inform future bee-friendly prairie planting projects, I conducted studies examining honey bee foraging choices. In Chapter 1, I gave honey bee colonies access to large, reconstructed prairies and recorded their recruitment behaviors (decoding and mapping waggle dance communications). I found that honey bee foragers mainly danced to advertise non-prairie flower patches and non-native flowers as profitable pollen sources, but seven native prairie taxa were also advertised as profitable pollen sources. At one site colonies became significantly more likely to advertise nectar sources in prairies in August/September. In Chapter 2, I gave honey bee colonies access to reconstructed prairies and concentrated plantings of native prairie species to further explore how access to prairies affects colony diet breadth. That study showed major contributions of non-native pollen sources, but colonies collected native prairie and native non-prairie sources as well, especially at the end of the season in most sites. The taxa most frequently collected tend to grow in dense patches, suggesting that planting density may have a strong effect on honey bee recruitment. In Chapter 3, I tested a recently-published method for mapping honey bee waggle dances using data collected during the study presented in Chapter 1. In Chapter 4, I used that new method to examine how the density of flowers in a patch affects honey bee recruitment behavior. This approach was novel as previous studies on recruitment used point-source sugar feeders. While my first attempt did not reveal significant preferences for more dense patches of flowers, it did highlight lessons for future experiments that manipulate variables at the flower patch level to better understand the factors that drive honey bee recruitment. Overall, these results provide insights into which species are most likely to attract honey bees to bee-friendly plantings in the Upper Midwest.