Nocturnal questing behavior of the blacklegged tick (Ixodes scapularis)

The blacklegged tick, Ixodes scapularis, is a vector to many pathogens including the agent of Lyme disease. Recent changes in climate have increased the average nighttime temperatures across Wisconsin which could impact the nighttime questing behavior of I. scapularis. The purpose of our study was to determine the daytime and nighttime questing pattern of I. scapularis. Ticks were collected at the Big Eau Pleine County Park during July and August of 2014 and June, July and August of 2015 by dragging a 1m² cloth drag through the forest understory. Ticks were collected over a period of 24 hours. Collections in July 2014 showed dramatic increases in the abundance of questing larvae and nymphs during the nighttime compared to the daytime hours and temporal shifts in abundance also were observed in August 2014. Collections in June 2015 again showed increased numbers of questing larvae and nymphs during the nighttime compared to the daytime hours, but the patterns in July and August did not show differences in nighttime vs daytime abundance. Differences in questing patterns could be attributed to variation in interannual weather as our site experienced cooler and milder weather in July and August 2015 compared to 2014. Despite differences in the number of questing ticks over 2014 and 2015, our study shows large numbers of larvae and nymphs questing during the nighttime that has not been recognized but should be considered in the ecology and epidemiology of tick-borne diseases.