Effects of Landscape Fragmentation, Habitat, and Vegetation on Abundance of Ixodesscapularis as a Lyme Disease Carrier in Essex County, Massachusetts

Abstract

The blacklegged tick (Ixodes scapularis) is the main vector for the Lyme disease‐causing spirochete Borrelia burgdorferi, which is transmitted to humans through the tick's bite. One explanation for the increased incidences in Lyme disease and tick abundance in the Northeast is fragmentation, in which continuous forest is transformed into small isolated patches. This study sought to connect landscape, habitat, and vegetation variables with Lyme disease prevalence. We monitored tick abundance among larva, nymph, and adult stages at 16 study sites representing 4 different habitat types (natural edge, pasture edge, residential edge, interior forest) in Essex County, MA. In order to detect the etiologic agent, B. burgdorferi, we isolated DNA and performed nested PCR to the 16S‐23S rRNA intergenic spacer region. Results showed that larvae correlated positively with % vegetation cover, total basal area (TBA) deciduous, and tree richness, but negatively to coniferous density. Nymphs demonstrated a positive relationship with % vegetation cover, TBA deciduous, and tree richness, but a negative relationship with coniferous density, deciduous density, and leaf litter. At a landscape scale, adults showed a positive relationship to human edge (forest edge created by humans) within a 500 m radius of the sampling point. Based on preliminary results, nested PCR has yielded adult ticks positive for B. burgdorferi, but additional data is needed in order to determine the relationship between Lyme disease prevalence and landscape, habitat, and vegetation variables. This work is supported by internal funding from Gordon College.