Associations between soil salinity, plant communities, and predaceous arthropods affecting ixodid distribution on the South Texas coastal plain

Authors: Showler, Allan

Submitted to: Journal of Vector Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: The subtropical coastal plain of deep South Texas provide a wildlife corridor for hosts of disease-transmitting ticks, including the southern cattle fever tick. Wind tides and storm surges push hypersaline Lower Laguna Madre water inland on occasion, creating substantial areas of saline soil dominated by sea ox-eye daisy, and inhabited by numerous mud flat fiddler crabs. Tick populations, especially larvae, in the saline areas are mostly negligible because of salt water toxicity to eggs, desiccation, and predators. Soil salinity, mud flat fiddler crab populations, and ant foraging activity were determined for areas dominated by sea ox-eye daisy, areas with intermediate stands, and areas without the plant. Sea ox-eye daisy density and mud flat fiddler crab populations were moderately correlated with soil salinity but predatory ant foraging was not correlated with soil salinity, sea ox-eye daisy density, and mud flat fiddle crab abundance. Sea ox-eye daisy stand density, however, was strongly correlated with numbers of mud flat fiddler crab holes, hence, the plant is an indicator of negligible tick activity. GIS mapping of high-sea ox-eye daisy habitats might be useful for refining surveillance of tick populations, particularly one-host ticks, such as the southern cattle fever tick.

Technical Abstract: The subtropical coastal plain of deep South Texas provide a wildlife corridor for hosts of disease-transmitting ixodid species, including the southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini). Wind tides and storm surges push hypersaline Lower Laguna Madre water inland on occasion, creating substantial areas of saline soil dominated by sea ox-eye daisy, Borrichia frutescens (L.) DC, and inhabited by numerous mud flat fiddler crabs, Uca rapax (Smith). Ixodid populations, especially larvae, in the saline areas are mostly negligible because of salt water toxicity to eggs, desiccation, and predators. Soil salinity, U. rapax populations, and ant foraging activity were determined for areas dominated by B. frutescens, areas with intermediate stands, and areas without the plant. Borrichia frutescens density and U. rapax populations were moderately correlated with soil salinity but predatory ant foraging was not correlated with soil salinity, B. frutescens density, and U. rapax abundance. Borrichia frutescens stand density, however, was strongly correlated with numbers of U. rapax holes, hence, the plant is an indicator of negligible ixodid activity. GIS mapping of high-Borrichia habitats might be useful for refining surveillance of tick populations, particularly one-host ixodid ticks, such as R. microplus.