Data from: Responses of juvenile blacklegged ticks (Acari: Ixodidae) to hosts of varying quality
Data files
Abstract
Blacklegged ticks (Ixodes scapularis) are the most medically and economically important vectors in North America. Each of their three life stages requires a bloodmeal from one of many potential host species, during which they can acquire or transmit pathogens. Host species, however, vary tremendously in their quality for ticks, as measured by differences in feeding and molting success. There should be clear fitness benefits for ticks that preferentially feed upon high-quality hosts (e.g., white-footed mice, Peromyscus leucopus), or at least avoid feeding on very low-quality hosts (e.g., Virginia opossums, Didelphis virginiana). Indeed, laboratory experiments have found some evidence of host preferences in I. scapularis; but these involve presenting ticks with hosts simultaneously and measuring movement towards hosts on a horizontal plane. In nature, however, host seeking ticks encounter hosts sequentially and their movements are principally in a vertical plane. Here, we present the results of a study in which we measured the vertical movements of host-seeking juvenile blacklegged ticks before and after a host (P. leucopus, Tamias striatus, Sciurus carolinensis, or D. virginiana) was present, and whether the strength of their responses vary with host quality. We found ticks did not measurably alter the speed of their vertical movement in the presence of any hosts, regardless of host quality. Both larvae and nymphs quested slightly higher in the presence of hosts, but this did not vary by host species. These results call into question the existence of active host preferences, at least in this stage of the host seeking process. Keywords: Vector Ecology, Ecology & Behavior, Ixodidae Entomological Society of America Editorial Office: 170 Jennifer Road, Suite 230, Annapolis, MD 21401, USA. Editorial Office Phone: 1-301-731-4535.
These data come from an experiment designed to determine if larval and nymphal blacklegged ticks (Ixodes scapularis) alter their vertical movements (i.e., "questing") in the presence of hosts, and whether any changes in these behaviors scale with the quality of the host species. We used wild caught white-footed mice (Peromyscus leucopus), eastern chipmunks (Tamias striatus), gray squirrels (Sciurus carolinensis), and virginia opossums (Didelphus virginiana) as our host species, as these species span the spectrum from high-quality to very low-quality hosts. We placed ticks on clear, vertical rods, and tracked their locations on the rods without a host present, and then after a host was placed.
Description of the data and file structure
Data are measurements of either the average height or the total distance travelled in cm (converted to "speed" within the provided code) in the absence or presence of a host. We have separate data files for larva height, nymph height, larva speed, and nymph speed (four csvs). Each data file has the same structure and columns, with the exception of the columns "absent" and "present". The shared columns for each data frame are the following: - HostID: A unique identifier for each host individual.
- TickID: An ID for each tick tracked in a single trial (these values are based on tick groups and rod number, they will repeat for different host individuals)
- Ticks: A unique identifier for a single tick responding to a host individual, created by combining HostID & TickID.
- Group: An ID for the vial ticks in a trial came from. Ticks with the same group ID were collected at the same time and held in the same vial for the duration of the experiment.
- Species: Species of the host used in a trial (PL = Peromyscus leucopus, TS = Tamias striatus, SC = Sciurus carolinenses, DV = Didelphus virginiana).
- Date: Date the trial was conducted.
dflh.csv includes data measuring the average height of a larval tick on the rod in the absence and presence of a host individual. Each row is the average questing height of a single tick before and after the addition of a host. In addition to the above columns, this csv includes:
- absent: Average height of a larval tick in the absence of any host. This measurement is scaled between 0 and 1, with 0 being the bottom of the rod where the clay base meets the water line, and 1 being the top of the rod. The rods used in larval experiments were 10cm tall.
- present: Average height of a larval tick after the addition of a host. This measurement is scaled between 0 and 1, with 0 being the bottom of the rod where the clay base meets the water line, and 1 being the top of the rod. The rods used in larval experiments were 10cm tall.
dfnh.csv includes data measuring the average height of a nymphal tick on the rod in the absence and presence of a host individual. Each row is the average questing height of a single tick before and after the addition of a host. In addition to the above columns, this csv includes:
- absent: Average height of a nymphal tick in the absence of any host. This measurement is scaled between 0 and 1, with 0 being the bottom of the rod where the clay base meets the water line, and 1 being the top of the rod. The rods used in nymphal experiments were 13cm tall.
- present: Average height of a nymphal tick after the addition of a host. This measurement is scaled between 0 and 1, with 0 being the bottom of the rod where the clay base meets the water line, and 1 being the top of the rod. The rods used in nymphal experiments were 13cm tall.
dfls.csv includes data measuring the total distance a larval tick on travelled on the rod in the absence and presence of a host individual. Each row is the total distance travelled of a single tick before and after the addition of a host. In addition to the above columns, this csv includes:
- absent: Total distance a larval tick travelled (in cm) in the absence of any host during the 6 minute observation period.
- present: Total distance a larval tick travelled (in cm) in the presence of a host during the 6 minute observation period.
dfns.csv includes data measuring the total distance a nymphal tick on travelled on the rod in the absence and presence of a host individual. Each row is the total distance travelled of a single tick before and after the addition of a host. In addition to the above columns, this csv includes:
- absent: Total distance a nymphal tick travelled (in cm) in the absence of any host during the 6 minute observation period.
- present: Total distance a nymphal tick travelled (in cm) in the presence of a host during the 6 minute observation period.
Code/Software
All models are specified using Stan code (_.stan files) which are run in R. The Stan models are as follows:
- mh1.stan: Height model with species specific host effect.
- mh2.stan: Height model with generic (not species specific) host effect.
- mh3.stan: Height model with no host effect.
- ms1.stan: Speed model with species specific host effect.
- ms2.stan: Speed model with generic host effect.
- ms3.stan: Speed model with no host effect.
The TickQuestingBehaviors.pdf and similar files contain the R code to run the above Stan models and generate paper figures.
- Burton, Emily; Ostfeld, Richard; Brunner, Jesse (2024), Data from: Responses of juvenile blacklegged ticks (Acari: Ixodidae) to hosts of varying quality, , Article, https://doi.org/10.5281/zenodo.12775407
- Burton, Emily; Ostfeld, Richard; Brunner, Jesse (2024), Data from: Responses of juvenile blacklegged ticks (Acari: Ixodidae) to hosts of varying quality, , Article, https://doi.org/10.5281/zenodo.12775408