Multi-scale patterns of tick occupancy and abundance across an agricultural landscape in southern Africa

PLoS One. 2019 Sep 20;14(9):e0222879. doi: 10.1371/journal.pone.0222879. eCollection 2019.

Abstract

Land use influences the prevalence and distribution of ticks due to the intimate relationship of ticks with their environment. This relationship occurs because land use alters two essential tick requirements: vertebrate hosts for blood meals and a suitable microclimate when off-host. Given the risks to human and animal health associated with pathogens transmitted by ticks, there is an ongoing need to understand the impact of environmental drivers on tick distributions. Here, we assessed how landscape features, neighborhood effects, and edges influenced tick occupancy and abundance across an agricultural landscape in southern Africa. We found that Rhipicephalus appendiculatus and Rhipicephalus simus increased in abundance closer to protected savanna, while Haemaphysalis elliptica increased in abundance closer to human habitation. The composition of the landscape surrounding savanna patches also differentially influenced the occupancy of each tick species; H. elliptica was more likely to be found in savanna patches surrounded by subsistence agriculture while R. appendiculatus and R. simus were more likely to be found in savanna surrounded by sugarcane monocultures. At the local scale we found that R. appendiculatus and R. simus avoided savanna edges. The availability of hosts and variation in vegetation structure between commercial agriculture, subsistence agriculture, and savanna likely drove the distribution of ticks at the landscape scale. Understanding how anthropogenic land use influences where ticks occur is useful for land use planning and for assessing public and animal health risks associated with ticks and tick-borne diseases.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Africa, Southern / epidemiology
  • Animals
  • Ecosystem*
  • Humans
  • Population Density
  • Population Dynamics
  • Rhipicephalus / immunology*
  • Rhipicephalus / physiology
  • Seasons*
  • Tick Infestations / epidemiology
  • Tick Infestations / immunology*
  • Tick Infestations / parasitology
  • Tick-Borne Diseases / epidemiology
  • Tick-Borne Diseases / immunology*
  • Tick-Borne Diseases / parasitology

Grants and funding

KL was supported by the National Science Foundation Graduate Research Fellowship under grant no. DGE-1842473. This study was funded by NSF ISE grant (no. 1459882) and the College of Agriculture and Life Science at the University of Florida.