title: Scale-dependent effects of nonnative plant invasion on host-seeking tick abundance.
abstract: Nonnative, invasive shrubs can affect human disease risk through direct and indirect effects on vector populations. Multiflora rose (Rosa multiflora) is a common invader within eastern deciduous forests where tick-borne disease (e.g. Lyme disease) rates are high. We tested whetherR. multiflorainvasion affects blacklegged tick (Ixodes scapularis) abundance, and at what scale. We sampled host-seeking ticks at two spatial scales: fine-scale, withinR. multiflora-invaded forest fragments; and patch scale, amongR. multiflora-invaded andR. multiflora-free forest fragments. At a fine scale, we trapped 2.3 times more ticks underR. multifloracompared to paired traps 25 m away fromR. multiflora. At the patch scale, we trapped 3.2 times as many ticks inR. multiflora-free forests compared toR. multiflora-invaded forests. Thus, ticks are concentrated beneathR. multiflorawithin invaded forests, but uninvaded forests support significantly more ticks. Among all covariates tested, leaf litter volume was the best predictor of tick abundance; at the patch scale,R. multiflora-invaded forests had less leaf litter than uninvaded forests. We suggest that leaf litter availability at the patch-scale plays a greater role in constraining tick abundance than the fine-scale, positive effect of invasive shrubs.
authors.affiliation: Department of Entomology and Wildlife Ecology, University of Delaware, Newark, Delaware 19716 USA.
authors.forename: Solny A
authors.initials: SA
authors.lastname: Adalsteinsson
authors.affiliation: United States Department of Agriculture Forest Service, Northern Research Station, Newark, Delaware 19716 USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: D'Amico
authors.affiliation: Department of Entomology and Wildlife Ecology, University of Delaware, Newark, Delaware 19716 USA.
authors.forename: W Gregory
authors.initials: WG
authors.lastname: Shriver
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 USA.
authors.forename: Dustin
authors.initials: D
authors.lastname: Brisson
authors.affiliation: Department of Entomology and Wildlife Ecology, University of Delaware, Newark, Delaware 19716 USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Buler
keywords: Ixodes scapularis; Rosa multiflora; forest fragmentation; invasive species; nonnative plant; scale