Current and Future Habitat Suitability Models for Four Ticks of Medical Concern in Illinois, USA

Abstract

The greater U.S. Midwest is on the leading edge of tick and tick-borne disease (TBD) expansion, with tick and TBD encroachment into Illinois occurring from both the northern and the southern regions. To assess the historical and future habitat suitability of four ticks of medical concern within the state, we fit individual and mean-weighted ensemble species distribution models for Ixodes scapularis, Amblyomma americanum, Dermacentor variabilis, and a newly invading species, Amblyomma maculatum using a variety of landscape and mean climate variables for the periods of 1970–2000, 2041–2060, and 2061–2080. Ensemble model projections for the historical climate were consistent with known distributions of each species but predicted the habitat suitability of A. maculatum to be much greater throughout Illinois than what known distributions demonstrate. The presence of forests and wetlands were the most important landcover classes predicting the occurrence of all tick species. As the climate warmed, the expected distribution of all species became strongly responsive to precipitation and temperature variables, particularly precipitation of the warmest quarter and mean diurnal range, as well as proximity to forest cover and water sources. The suitable habitat for I. scapularis, A. americanum, and A. maculatum was predicted to significantly narrow in the 2050 climate scenario and then increase more broadly statewide in the 2070 scenario but at reduced likelihoods. Predicting where ticks may invade and concentrate as the climate changes will be important to anticipate, prevent, and treat TBD in Illinois.

Design and partial validation of novel eDNA qPCR assays for three common North American tick (Arachnida: Ixodida) species

“…A different sampling approach would likely be necessary to capture the small amounts of residual tick DNA spread across a large grass field or forest plot. This consideration particularly applies to I. scapularis , a specie currently more abundant in the northern third of the state (Kopsco et al., 2023; Rydzewski et al., 2011, 2012), and is relatively scant in central and southern Illinois, where our sampling occurred, compared to the other three species.…”

“…Collection sites were characterized by a mix of three habitat types: open prairie, mowed prairie or forest edge, and mixed deciduous understory. These habitats included preferential environments within the state for each of the three targeted tick species and have documented tick presence (Bacon et al., 2022; James et al., 2015; Kopsco et al., 2023). Three 250 m linear transects were established at each site (one transect per habitat type) and sampled for both ticks and plant matter via a block random design (without replacement) to reduce bias (i.e., one of the three transects was selected at random for each site per visit, for a total of three visits per site on average throughout the field season; Figure 1b).…”

“…Additionally, the plant material sampled by Lyman et al (2022) was used as nesting material by the small rodents which likely increased the amount of eDNA on the surface of these plants. Species like I. scapularis and D. variabilis, however, employ a sit-and-wait host-seeking strategy, waiting for mammals to move by them, so they are often not moving through a field and shedding DNA on plants they pass by (Sonenshine & Roe, 2014) (Kopsco et al, 2023;Rydzewski et al, 2011Rydzewski et al, , 2012, and is relatively scant in central and southern Illinois, where our sampling occurred, compared to the other three species.…”

Assessing knowledge gaps and empowering Extension workers in Illinois with information on ticks and tickborne diseases through KAP surveys

“…The increase in TBD cases has coincided with the geographic range expansion of the medically important vector tick species Ixodes scapularis , Amblyomma americanum , Amblyomma maculatum and Dermacentor variabilis [ 7 ]. Previous research found that factors associated with climate change, such as maximum average temperature and total precipitation [ 8 ], presence of forest cover in metropolitan areas [ 9 ] and wetlands [ 10 ], open habitats with minimal canopy cover [ 11 ] are associated with distribution and abundance of various tick species in Illinois. Thus, the number of tick species and cases of TBDs in the Upper Midwest region is likely to follow an upward trend in the coming decades.…”

Genome resequencing reveals population divergence and local adaptation of blacklegged ticks in the United States

“…Human disease incidence is known to depend upon the distribution and abundance of established populations of infected tick vectors (Falco et al., 1999; Pepin et al., 2012), yet the spatial distribution of tick populations is highly variable. Landscape and habitat suitability studies have found associations between I. scapularis abundance or presence with habitat features such as forest cover and soil type in the midwestern United States (Gardner et al., 2020; Kopsco et al., 2023), but there is often no clear relationship with a major host for the juvenile stages, white‐footed mice (Guerra et al., 2002). Movement patterns have also been difficult to reconstruct, though there is evidence that I. scapularis spatial expansion can be relatively rapid (Clow et al., 2017), despite the fact that ticks are flightless and crawl only a few metres (Daniels & Fish, 1990), pointing to the importance of host‐associated transport in their dispersal.…”