SPATIAL DISTRIBUTION, HABITAT PREFERENCE, AND SOCIETAL IMPACT OF THE NUISANCE BLACK FLY, SIMULIUM JENNINGSI

Abstract

Black flies (Diptera: Simuliidae) can cause pest problems through the females’ blood-seeking behavior. Nuisance black flies are managed through area-wide pest management at the larval stage, which necessitates tracking the distribution of both life stages. The species Simulium jenningsi is a nuisance pest in the mid-Atlantic United States. In Washington County, Maryland, residents began campaigning for state management of S. jenningsi in 2013. In my dissertation I used the localized nature of the S. jenningsi nuisance in western Maryland to investigate the environmental correlates to S. jenningsi abundance patterns and how this pest impacts the lives of residents. Survey responses regarding the annoyance and impact of black flies on resident quality of life were used to assess the societal component of S. jenningsi nuisance. Online respondents, those with children, and those who had lived in the region for a shorter amount of time were more likely to report black flies as “extremely annoying.” Quality of life concerns stemmed from avoidance of exercise and dissatisfaction with preventative strategies. The results contextualized the needs of residents in future management and topics for outreach efforts. Distribution patterns of the host-seeking females were studied within a 2000 km2 area centered on Washington County. High counts of flies were clustered in southern Washington County, although S. jenningsi could be found throughout the sampling area. Regression analysis showed relationships between higher adult fly abundance and environmental factors, including higher elevation, less surrounding impervious surface, and closer proximity to productive larval habitat. The factors associated with immature S. jenningsi abundance were studied at eight sites spanning the Potomac and Shenandoah Rivers. Simulium luggeri, a related species not identified as a pest in Maryland, was also found at each location. S. jenningsi was associated with higher flow velocity and temperature, while S. luggeri was associated with higher seston chlorophyll a content. Both species were associated with higher surrounding tree canopy, implying a possible connection to oviposition cues. Results from this dissertation suggest factors associated with optimal monitoring locations for adult S. jenningsi and indicate management should focus on areas of high flow velocity for larval populations.