The climate niche of the invasive tick species Hyalomma marginatum and Hyalomma rufipes (Ixodidae) with recommendations for modeling exercises

Abstract

The finding of immature stages of some Hyalomma spp. feeding on migratory birds in Europe is unexceptional. The reports of adults of Hyalomma in Europe (incl. the British Isles) after successful molting from immatures have increased in recent years. It has been claimed that the warming of the target territory could favor the populations of these invasive ticks. Although evaluations of the impact on health or measures of adaptation are on their way, the climate niches of these species remain undefined, preventing preventive policies. This study delineates such niches for both Hyalomma marginatum (2,729 collection points) and Hyalomma rufipes (2,573 collections) in their distribution area, together with 11,669 points in Europe where Hyalomma spp. are believed to be absent in field surveys. Niche is defined from daily data of temperature, evapotranspiration, soil humidity and air saturation deficit (years 1970–2006). A set of eight variables (annual/seasonal accumulated temperature and vapor deficit) has the maximum discriminatory power separating the niches of both Hyalomma and a negative dataset, with an accuracy near 100%. The sites supporting H. marginatum or H. rufipes seem to be controlled by the joint action of the amount of water in the air (accounting for mortality) and the accumulated temperature (regulating development). The use of accumulated annual temperature as the only variable for predictive purposes of colonization of Hyalomma spp. looks unreliable, as far as values of water in air are excluded.

Molting incidents of Hyalomma spp. carrying human pathogens in Germany under different weather conditions

“…Moreover, the two Hyalomma species have different tolerance levels of relative humidity [ 26 , 27 ]. Although humidity is regarded as equally important as temperature for defining the climate niche of both species [ 56 ], the seasonal drought index was not significantly associated with the Hyalomma occurrence locations in the present study. As mentioned before, due to the limitations of the citizen science approach, it was not possible to compare the Hyalomma numbers across years, but higher rainfall might explain the lower number of findings in 2021 compared to the preceding years.…”

Predicting climate-driven distribution shifts inHyalomma marginatum(Ixodidae)

“…In addition, surface radiation is replaced by gdd0 (growth degree days above 0 ), which was eliminated from Model 1 due to correlation threshold with other parameters. Fulfilling the required degree days is an important necessity for H. marginatum populations to establish in a new region (Estrada-Peña, 2023). It has been reported that an accumulated temperature of 3000-4000 is necessary for this species; a northern limit roughly coincides with 47 N (Estrada-Peña et al, 2011;Gillingham et al, 2023).…”

“…We used Chelsa V2.1 dataset (Karger et al, 2017(Karger et al, , 2022 available at https://chelsa-climate.org, a relatively new high-resolution (30 arc sec, ~1km) climate dataset that includes additional important microclimatic variables in addition to the counterparts (Chelsa-Bioclim) of popular WorldClim bioclim variables (Fick & Hijmans, 2017;Hijmans et al, 2005). These include variables related with microclimate, water content of air, and humidity which are important for H. marginatum (Estrada-Peña, 2023;Estrada-Peña et al, 2011). Furthermore, while the WorldClim dataset used for current distribution predictions uses extrapolations made between 1970-2000, the Chelsa dataset uses a dataset made for the period between 1980-2010.…”

High-resolution prediction models for Rhipicephalus microplus and Amblyomma cajennense s.l. ticks affecting cattle and their spatial distribution in continental Ecuador using bioclimatic factors

“…This information is available at a horizontal resolution of 30 arc sec. Although relative humidity has been commonly used, vapor pressure deficit (VPD) is a more useful parameter for evaluating environmental conditions in relation to tick development, as it accounts for the air’s drying power (Wollaeger and Runkle 2015 ; Pascoe et al 2019 ; Estrada-Peña 2023 ). The VPD data was calculated from hurs, considered a unitless fraction, and tas in ◦C as with this formula: VPD = e sat (tas) × (1 − hurs) where hurs is the relative humidity, e sat (tas) is the saturation vapor pressure.…”

“…While hosts are necessary for tick presence, we expect cattle tick survival and development to be affected by bioclimatic variables such as rainfall and temperature, that affect the number of generations per year, and thus, abundance. The most limiting factors for their presence, as well as the tick ecotype, can vary between regions (Lima et al 2000 ; Estrada-Peña 2023 ) (Lima et al 2000 ; Estrada-Peña et al 2006b ). At broad scales, climate factors have been found useful to delimit tick distribution (Estrada-Peña et al 2006a , b ).…”