Soft ticks perform evaporative cooling during blood-feeding

Area of Science:

• Zoology
• Arthropod Physiology
• Thermoregulation

Background:

• Haematophagous arthropods face thermal stress when feeding on warm-blooded hosts.
• Insects utilize heat-shock proteins or thermoregulation to maintain physiological integrity.
• Tick thermoregulation strategies remained largely undescribed.

Purpose of the Study:

• To describe the thermoregulatory mechanism in the tick Ornithodoros rostratus.
• To investigate how Ornithodoros rostratus copes with thermal stress during feeding.

Main Methods:

• Real-time infrared thermography was employed during tick feeding on mice.
• Observation of fluid elimination and its spread on the tick's cuticle.

Main Results:

• Ornithodoros rostratus eliminates significant amounts of fluid (urine) via coxal glands.
• Evaporation of this fluid from the cuticular surface effectively cools the tick.
• Capillary diffusion through the exoskeleton facilitates fluid spread.

Conclusions:

• This study presents the first documented thermoregulatory mechanism in a tick species.
• Fluid evaporation from coxal glands is an adaptive strategy for Ornithodoros rostratus to manage feeding-induced thermal stress.
• Findings contribute to understanding arthropod adaptations to host-associated thermal challenges.