Microhabitat-independent regional differences in survival of unfed Ixodes scapularis nymphs (Acari:Ixodidae) in Connecticut

Abstract

The effects of habitat and microclimate on survival of unfed nymphal black-legged ticks, Ixodes scapularis Say (approximately I. damnini Spielman, Clifford, Piesman & Corwin), were studied under natural conditions in southcentral and northwestern Connecticut. At both coastal and inland locations, survival of 3 groups of 20 wild-caught questing nymphs placed in nylon mesh bags was monitored in each of 3 different habitats (field, forest canopy, and forest/field edge) during summer 1995. Simultaneously, soil temperature, ground-level air temperature, and relative humidity were measured continuously within each habitat at both sites. The number of ticks surviving in each habitat was monitored weekly. Average daily survival rates of nymphs were related inversely to soil temperature but were not related to air temperature or humidity. Overall, nymphal ticks at the inland site survived significantly longer than those at the coastal site; however, no significant differences in mortality rates were found among habitats. These results suggest that inland environmental conditions are suitable for lengthy survival of unfed nymphal I. scapularis in regions where this tick is not yet abundant.