Morphological responses to feeding in ticks (Ixodes ricinus)

Area of Science:

• Arthropod physiology
• Tick biology
• Morphological adaptations

Background:

• Ticks undergo extreme body volume changes during feeding.
• The castor bean tick (Ixodes ricinus) is studied for its adaptations to feeding-induced volume increases.

Purpose of the Study:

• To investigate the morphological adaptations enabling volume changes in the opisthosoma of feeding ticks.
• To understand the functional morphology that accommodates significant volume increases.

Main Methods:

• Light and electron microscopy were used.
• Comparison of cuticle, epidermis, midgut diverticula, and tracheae in fasting, semi-engorged, and fully engorged ticks.

Main Results:

• Epidermal and midgut diverticula cells change shape and size (hypertrophy) to accommodate volume.
• Tracheae elongate but do not increase in diameter, maintaining oxygen supply.
• No evidence of cell proliferation was found.

Conclusions:

• Epithelial tissue reconfiguration in the epidermis and midgut is crucial for tick feeding adaptation.
• Expandable tracheae, a novel mechanism in arthropods, were identified in Ixodes ricinus.
• These adaptations ensure oxygen delivery to tissues as body volume increases.