Longer study length, standardized sampling techniques, and broader geographic scope leads to higher likelihood of detecting stable abundance patterns in long term black-legged tick studies

Abstract

Ixodes scapularis (deer ticks) are a taxon of ecological and human health concern due to their status as primary vectors of Borrelia burgdorferi, the bacteria that transmits Lyme disease. Deer ticks are thought to be expanding in geographic range and population size across the eastern US, leading to concern that tick-vectored illness will correspondingly rise. However, because of wide variability in deer tick monitoring strategies, synthesis efforts may be limited by the sensitivity and reliability of data produced by existing long term studies, especially to inform forecasting and proactive deer tick management. To address this, we explicitly examined the role of how study design parameters affect the likelihood of observing temporal trends in deer tick studies. We used a moving window approach to investigate the temporal stability of deer tick population trajectories across the US. We found several study factors can have an impact on the likelihood of a study reaching stability and the likelihood of tick abundance data leading to misleading results if the study does not reach stability. Our results underscore the need for longer studies of deer ticks when trying to assess long term or broad spatial patterns. Moreover, our results showcase the importance of study length, sampling technique, life stage, and geographic scope in shaping the inferences from deer tick studies. This is especially important for synthesizing across the variety of existing surveys and for potential ecological forecasting.