Spatiotemporal dynamics of Amblyomma americanum abundance and infection prevalence across a subcontinental scale

Abstract

Tick dynamics and tick infection prevalence are influenced directly by climate conditions (e.g., temperature, precipitation) and indirectly by mast seeding patterns of trees that influence the abundance of tick hosts such as small mammals. Tick and tick‐borne disease dynamic studies have been done primarily at local scales, which represent a small fraction of the geographical range of ticks across the United States; it is not yet known how synchronous tick dynamics are at a macrosystems scale. Here, we explored patterns and potential drivers of spatiotemporal synchrony of tick abundance dynamics for the lone‐star tick, Amblyomma americanum , on a subcontinental scale, and test whether climate variables are associated with A. americanum nymph abundance and pathogen prevalence. We used 8 years of tick drag and tick pathogen data from the National Ecological Observatory Network (NEON), with a focus on seven distinct eco‐regions (“domains”) across the NEON network of sites, spanning over 2000 km. Multiple regression on distance matrices (MRM) analysis found that intraspecific spatial synchrony in temporal patterns of nymph abundance declined with increasing distance between NEON sites. A. americanum nymph dynamics were influenced by lags in July temperature differences, ∆ T ₃ (difference in mean July temperatures in year t  − 3 minus t  − 4) and ∆ T ₄ (difference in mean July temperatures in year t  − 4 minus t  − 5), and July temperatures and June precipitation were most strongly associated with the proportion of infected A. americanum nymphs. Understanding the synchrony and drivers of tick dynamics and tick infection prevalence across large spatial scales—knowing whether tick populations and tick‐borne disease risk are high throughout their range, or not—could influence public messaging about ticks and the risk of tick‐borne diseases.