Native and invaded plant communities alter tick exposure risk via different mechanistic pathways

Plant invasions may alter vector-borne disease risk by modifying
microclimates that influence vector survival, or by changing habitat
conditions that determine reservoir host use. Here, we evaluated multiple
mechanistic pathways by which plant invasion may alter vector-borne
disease risk using the common disease vector lone star tick (Amblyomma
americanum) and the widespread invasive cogongrass (Imperata cylindrica)
in the southeastern USA. Ticks survived over 50% longer in invaded than
native plant species dominated communities, likely due to lower
temperature and higher humidity conditions. However, wildlife host
activity was higher in native than invaded plant species dominated
communities. As a result, host-seeking tick abundances were similar
between invaded and native areas, albeit through different mechanisms:
longer survival maintained tick abundances in invaded areas while greater
host use maintained tick abundance in native areas. Multiple, potentially
off-setting mechanistic pathways should be considered when evaluating
possible effects of invasive plants on vector-borne disease risk.