Amblyomma ticks and future climate: Range contraction due to climate warming

Area of Science:

• Ecology
• Environmental Science
• Vector-borne Diseases

Background:

• The Amblyomma cajennense species complex are significant vectors of spotted fever in Latin America.
• Environmental factors dictate tick distribution, making climate change a potential driver of tick-borne disease dynamics.

Purpose of the Study:

• To assess the potential geographic distribution of Amblyomma cajennense complex ticks in Brazil under current and future climate scenarios.
• To analyze tick distribution considering dispersal limitations and no evolutionary adaptation to climate warming.

Main Methods:

• Utilized presence records for Amblyomma cajennense sensu stricto (s.s.) and Amblyomma sculptum.
• Employed Maxent niche modeling with climate data from 1950-2000.
• Projected models using CCSM4 and HadGEM2-AO for 2050 and 2070 climate conditions.

Main Results:

• Identified broad suitable areas for both tick species under present-day climate models.
• Observed reduced suitability when projecting to future climate conditions.
• Highlighted the emergence of novel, extremely high temperatures in future climate models, leading to unrealistic suitability predictions.

Conclusions:

• Future climate projections indicate reduced suitable habitats for A. cajennense complex ticks, contrary to some expansion predictions.
• Novel climatic conditions in projected future scenarios may yield biologically unrealistic tick distribution forecasts.
• Caution is advised for studies predicting vector population expansion due to climate change without accounting for adaptation limitations.