Photo 1. In the Eastern United States, blacklegged tick (Ixodes scapularis) habitat includes hardwood, deciduous forests that provide leaf litter cover with (presumably) suitable microclimate conditions. In this study, field plots were established at three forested sites along the East Coast. From left to right, the sites are pictured from north to south: Fort Drum, NY, West Point, NY, and Camp Lejeune, NC. Ticks of all three life stages (larva, nymph, and adult), including flat (unfed) and engorged (fed) ticks, were placed in soil core enclosures (SCEs) that consisted of cylindrical cores of intact soil and leaf litter enclosed in a mesh bag, and protected from damage from raccoon or other mammals with wire mesh cages. Microclimate conditions were measured hourly at each site and tick survival and molting, or egg-laying success, were estimated by destructively sampling groups of SCEs at multiple points in time. At Camp Lejeune (the southernmost field site), where desiccating conditions were most frequently observed, median survival of unfed larvae was about 10 days shorter than those at Fort Drum (the northernmost field site). Photo credit: Megan Schierer. Photo 2. Hurricane Florence struck the Camp Lejeune field site on September 14, 2018, accompanied by a nearly 4 m storm surge and record-breaking 0.9 m of rainfall. Our field crew was prevented from accessing the base due to safety concerns. This photo was taken on October 2nd, 2018, on our first return visit. Some data logger data were compromised due to areas of the coastal field site having been fully underwater, and tick survival data from this period was removed from data analysis. No ticks were recovered from containers that withstood the hurricane and its aftereffects. Photo credit: Megan Schierer. Photo 3. Unfed (left) and fed (right) adult female blacklegged ticks prior to deployment in SCEs. Unfed ticks were field collected using drag cloths at sites in the general areas of those pictured in Photo 1. To obtain ticks in their fed state, adult female ticks (shown above) were fed on adult rabbits. Fed larvae and nymphs were obtained by feeding ticks on lab reared white-footed mice at the Cary Institute. Overall, molting success of fed ticks to the next life stage was high and most closely fit a degree day model at all sites, with Camp Lejeune degree days accumulating fastest, leading to the quickest molting time compared to West Point and Fort Drum. Photo credits: Megan Schierer (left) and Elizabeth Valentine (right). Photo 4. An SCE deployed in the field (left) alongside an SCE during a deconstructive survival/molting assessment. Over the three-year experiment, a total of 1145 SCEs, encompassing 12,004 ticks, were deployed across the three sites. Subsets of SCEs were transported back to the Cary Institute at biweekly intervals to be searched for surviving (or molted) ticks. In addition, data loggers were deployed – one in the soil and one under the white protective cups seen on the left – in half of the SCEs. Hourly temperature and humidity data were offloaded for analysis. Photo credits: Elizabeth Valentine (left) and Megan Schierer (right). Photo 5. Various preparation methods associated with the deployment of SCEs at field sites. Soil cores were created and inserted into PVC rings shrouded in a mesh bag and sealed at least 2 weeks prior to ticks being added (left and center). At the time of tick and data logger deployment, a second mesh bag was added to reduce chances of tick escapes from the SCEs, and the mesh bags were checked for holes at this time (right). During SCE preparation and deployment, project assistants worked in pairs to ensure careful handling of soil cores, data loggers, and ticks. Photo credits: Elizabeth Valentine. These photographs illustrate the article “Off-host survival of blacklegged ticks in eastern North America: A multistage, multiyear, multisite study” by J. L. Brunner, J. S. L. LaDeau, M. E. Killilea, E. Valentine, M. L. Schierer, and R. S. Ostfeld, published in Ecological Monographs. https://doi.org/10.1002/ecm.1572
Schierer et al. (Fri,) studied this question.