Determining Effects of Winter Weather Conditions on Adult Amblyomma americanum (Acari: Ixodidae) Survival in Connecticut and Maine, USA

Abstract

The lone star tick (Amblyomma americanum L.) is native to the United States, with its primary range encompassing the Southeast and portions of the Midwest. It is an aggressive ectoparasite that actively seeks out hosts through detection of carbon dioxide and vibrations and can transfer ehrlichiosis-causing bacteria as well as a carbohydrate that causes alpha-gal syndrome (red meat allergy) in humans. It has become of increasing concern as its range has recently expanded into coastal regions of the Northeast. Historically, harsh northeastern winter weather conditions made these areas inhospitable for A. americanum survival, but a warming climate coupled with increased host availability seem to have facilitated their range expansion. We developed a study to observe the effects of weather conditions on adult A. americanum overwintering survival. The study was conducted over three years in Connecticut and Maine. Ground-level conditions were manipulated to determine the effects of differing combinations of natural insulative barriers (leaf litter and snow accumulation) on adult A. americanum survival. We determined that there was a significant difference in survival between the two states, between years in Maine, and between sexes within Connecticut. However, presence or absence of snow and/or leaf litter had no impact on survival. Overall, we found a positive correlation between mean hourly temperature and adult survival in Maine, where temperatures were consistently below freezing. The results of this study can be included in an adaptive, predictive analytic model to accommodate the expected fluctuations and range expansion of A. americanum that will most likely accompany an increase in temperatures throughout the Northeast.

Spatio-temporal modelling of tick life-stage count data with spatially varying coefficients

“…It is clear that change in temperature affect tick numbers, such that they decrease in winter (Linske et al, 2020). We confirmed this unsurprising fact and noted also that larvae count remained low up to May.…”

Predicting the Potential Global Distribution of Amblyomma americanum (Acari: Ixodidae) under Near Current and Future Climatic Conditions, Using the Maximum Entropy Model

“…In [14], the authors showed that climate change will affect the growth, development and distribution of ticks, as temperature plays an important role in the lifecycle of ticks. When the temperature is lower than a certain value, the death probability of ticks will increase greatly, whereas an increase in temperature may help the species to be distributed in areas where the climate was previously unsuitable [15].…”

Lone Star Ticks (Amblyomma americanum):

“…In contrast to ticks that use an ambush strategy (i.e., lying in wait for a host to move by), lone star ticks actively seek hosts, attracted by carbon dioxide and vibrations from host movement. 2 To complete their life cycle, lone star ticks must take three blood meals, each from a different individual host; all three motile stages (larvae, nymphs, and adults) will readily feed on humans in addition to other vertebrate hosts. Each blood meal represents a possible exposure to pathogenic agents.…”

“…This range expansion is attributed to changing climatic factors such as shorter, milder winters, as well as the increasing abundance of preferred hosts like the white-tailed deer ( Odocoileus virgianus ), which in turn is facilitated by reduced predation pressure and changing land use patterns (e.g., forest fragmentation, suburbanization, and increased availability of edge habitat). 2 …”