Data from: Abiotic and habitat drivers of tick vector abundance, diversity, phenology and human encounter risk in southern California

The distribution, abundance and seasonal activity of vector species, such
as ticks and mosquitoes, are key determinants of vector-borne disease
risk, and are strongly influenced by abiotic and habitat conditions.
Despite the numerous species of tick vectors in the heavily populated
North American West Coast, all but Ixodes pacificus, the primary vector of
the Lyme disease spirochete, is poorly characterized with regard to
seasonal activity patterns and fine scale drivers of distribution and
abundance, particularly in heavily populated regions of southern
California. This lack of knowledge inhibits both scientific understanding
and public health efforts to minimize vector exposure and risk of pathogen
transmission to humans. Here we address this gap by characterizing the
abiotic and habitat drivers of the distribution, abundance, and diversity
of the vector tick community using fine scale temporal surveys over two
seasons (2014 and 2015) across coastal and inland regions of Santa Barbara
County, CA. We also characterize patterns of seasonal activity of the more
common vector species to understand seasonality in risk of vector
exposure, and specifically focus on human encounter risk using
standardized tick drags as our method of collection. Leveraging plot-level
habitat and abiotic variables in partial least squares regression
analysis, we find the seven different vector species collected in this
study have divergent drivers of activity and abundance. For example, I.
pacificus is strongly associated with dense forest habitats and cool and
moist microclimates, while Dermacentor occidentalis and Dermacentor
variabilis, competent vectors of Rocky Mountain Spotted Fever, were found
to be more tolerant of higher average temperatures and more open habitats.
These results suggest that I. pacificus may be expected to experience
reductions in geographic distribution and seasonal activity under
projected land cover and climate change in coastal southern California,
while D. occidentalis may experience more limited effects. We discuss
implications for changing tick-borne disease risk associated with
pathogens transmitted by Ixodes as well as Dermacentor species ticks in
the western US, and contrast these predictions with eastern North America.