Seasonal dynamics of Ixodes ricinus on ground level and higher vegetation in a preserved wooded area in southern Europe

Abstract

Ixodes ricinus is a major vector of pathogens affecting animals and humans in Europe. Despite its wide distribution, data on the ecology of I. ricinus in some areas is meager, which might impair the elaboration of reliable models to predict the risk of pathogen transmission in areas where this tick is currently present. Herein, we analyze some aspects of the ecology of I. ricinus in a wooded area of southern Italy. From March 2010 to March 2012, ticks were collected on a monthly basis by dragging and flagging in three different sites in a wooded area located in southern Italy, within the boundaries of the Gallipoli Cognato Forest, in the Basilicata region, southern Italy. Immature ticks were more abundant than adults (immature:adult ratio, 10.5:1). The abundance of larvae on the ground-level vegetation was generally higher than on higher vegetation (19.1 vs. 8.3 ticks per hour), whereas nymphs, males and females were more abundant on the higher vegetation (22.3 vs. 14.2, 2.9 vs. 0.8, 2.7 vs. 1.0 ticks per hour, respectively). Larvae were most abundant in summer (27.4 ticks per hour), whereas nymphs, females, and males peaked in seasons other than summer. This study underlines that I. ricinus is well adapted to southern Italian conditions, where it remains active during the whole year, displaying spatiotemporal distribution patterns that are different from central and north European populations. Remarkably, it points out that the life cycle of I. ricinus in southern Italy may be completed in approximately 1 year. Data generated will be valuable to elaborate better models to predict the distribution of this tick in Europe and to assess the risk of transmitted diseases, particularly Lyme borreliosis and tick-borne encephalitis.