Seasonal Variation in Nymphal Blacklegged Tick Abundance in Southern New England Forests

Abstract

In the northeastern United States, risk of human exposure to tick transmitted disease is primarily a function of the abundance of the blacklegged tick, Ixodes scapularis Say. We assessed seasonal variability in the abundance of nymphal stage I. scapularis over 13 yr, collected from several forested areas throughout Rhode Island. Specifically, we examined intraseasonal differences by using two temporally distinct tick collections made during the peak nymphal tick season. Intraseasonal factors significantly impacted tick abundance, with the June tick rate (mean = 40.42, SD = 14.79) significantly more abundant than the July tick rate (mean = 27.64, SD = 15.47). The greater variability in July (coefficient of variation: June, 36.61%; July, 55.95%) lead us to conclude June tick rates are relatively stable from year to year, whereas July tick rates contribute more to intraseasonal and yearly variation.