Short day-triggered quiescence promotes water conservation in the American dog tick, Dermacentor variabilis

Abstract

A short day-long day exposure comparison of water balance characteristics throughout the life history of the American dog tick, Dermacentor variabilis, was conducted to examine how this tick survives winter-associated dryness. Larvae, nymphs, and adults under potential diapause-inducing conditions (short day, 20 °C) have low water loss rates compared to long day exposed ticks. Above the critical equilibrium activity, these nonfed ticks show greater water gain from lower water vapor activities. In contrast to nonfed stages, eggs and blood-engorged stages (fed larva, fed nymph) were enhanced for water conservation independent of short day exposure and did not display reduced water loss rates under short day conditions. This short day-prompted response in nonfed ticks was distinguished from a genetically programmed diapause as noted in other arthropods by: (1) reduction in water loss was temporary and could be reversed quickly by transferring to long day for only a single day, then re-triggered by returning to short day conditions; (2) switch between low and high water loss rates could be induced multiple times and for multiple different stages; and (3) response by ticks was to the photoperiod they were under, not the condition that was experienced by previous fed stages or in the mother in the case of eggs. Furthermore, short day had no impact on altering body water content, dehydration tolerance limit, instar yields, or developmental stadia. We conclude that a short day-triggered quiescence reduces desiccation stress associated with overwintering in nonfed ticks. This effect on water conservation due to short day exposure is more pronounced for subadults and is likely due to their increased sensitivity to water loss as a result of their smaller size, which is critical to prevent dehydration during the dry winter periods.

Surveillance of Host-Seeking Ticks in the Flint Hills Region (USA) and Associations with Environmental Determinants

“…Ticks are poikilothermic arthropods whose survival and fitness are closely linked to ambient conditions. Temperature and moisture available in the atmosphere, represented either as relative humidity or saturation deficit, have been long shown to exert significant effect on the questing behavior [22,23], development rate [24][25][26][27] and reproduction and survival [28,29] of various ixodid ticks, and they are a major limiting factor of the geographic distribution of a tick species [30][31][32]. NDVI, an index for remotely detecting photosynthetic activity of plants is associated with A. americanum density in the present study.…”

“…However, it is important to consider the effect of saturation deficit not in isolation but in the presence of accumulated temperature and photoperiod as these covariates together contributed to the mixed model (Table 3). The effect of photoperiod on D. variabilis has been shown to affect the questing behavior [26,34], with longer photoperiods increasing questing activity. Similarly, the maximum relative humidity recorded per month is associated with the density of A. maculatum ticks, with lower relative humidity favoring increased density.…”

Effect of snow cover on the off-host survival of Dermacentor variabilis (Acari: Ixodidae) larvae

“…Larvae remain motionless during diapause (Diyes et al 2023). This decreased activity significantly reduces water loss and potential death due to dehydration (Yoder et al 2016). Ticks also actively select a suitable refuge site to overwinter (Sonenshine 1988).…”

Amblyomma mixtum free-living stages: Inferences on dry and wet seasons use, preference, and niche width in an agroecosystem (Yopal, Casanare, Colombia)

“…In hydrophilic species of ixodids, such as Ixodes uriae or Dermacentor variabilis , sub-adult stages (larvae and nymphs) tend to be more prone to water stress from drying out than adults [ 94 , 95 ]. However, A .…”