The Influence of Prescribed Fire, Habitat, and Weather on Amblyomma americanum (Ixodida: Ixodidae) in West-Central Illinois, USA

Abstract

The distribution of Amblyomma americanum (L.) is changing and reports of tick-borne disease transmitted by A. americanum are increasing in the USA. We used flagging to collect ticks, surveyed vegetation and collected weather data in 2015 and 2016. A. americanum dominated collections in both years (97%). Ticks did not differ among burn treatments; however, tick abundance differed between years among total, adult, and larval ticks. Habitat variables showed a weak negative correlation to total ticks in respect to: Shannon diversity index, percent bare ground, perennial cover, and coarse woody debris. Nymphal ticks showed a weak negative correlation to percent bare ground and fewer adults were collected in areas with more leaf litter and coarse woody debris. Conversely, we found larvae more often in areas with more total cover, biennials, vines, shrubs, and leaf litter, suggesting habitat is important for this life stage. We compared weather variables to tick presence and found, in 2015, temperature, precipitation, humidity, and sample period influenced tick collection and were life stage specific. In 2016, temperature, precipitation, humidity, wind, and sample period influenced tick collection and were also life stage specific. These results indicate that spring burns in an oak woodland do not reduce ticks; other variables such as habitat and weather are more influential on tick abundance or presence at different life stages.

Keywords: litter cover; lone star tick; microclimate; oak woodland; prescribed burning; tick ecology; vegetation structure.

Figure 1

Mean counts of Amblyomma americanum (L.) by life stage, collected from transects in 2015 (n = 30 transects) and 2016 (n = 30 transects) at Alice L. Kibbe Field Station in Hancock County, west-central Illinois. Bars superscripted with different letters indicate significant differences (p < 0.05) between years as indicated by one-way ANOVA. Larval ticks were considered present (1) or absent (0), means of presence and absence are depicted. Error bars represent one standard error.

Figure 2

Comparison of larval Amblyomma americanum (L.) presence (n = 19) and absence (n = 41) on transects during all sample periods with respect to (A) Average total vegetation cover, (B) Average vine cover, (C) Average biennial cover, (D) Average leaf litter cover, and (E) Average shrub cover. Ticks were collected in 2015 and 2016 at Alice L. Kibbe Field Station in Hancock County, west-central Illinois. Presence indicates ≥ 1 larval tick was collected on a transect during the sample periods; absence indicates no larval ticks were collected.