Large dermal gland secretions in ticks (Acari: Ixodidae) provide no water-proofing to the integument

The large dermal glands of ticks release a wax-based fluid that acts in defense (allomone) and prompts ticks to cluster (aggregation-attachment pheromone; clustering ‘alarm’ pheromone). This study investigates whether this secretion protects against dehydration in the lone star tick, Amblyomma americanum. No significant differences were observed in net water loss rates, critical transition temperatures and activation energies for water loss between controls versus ticks that had secreted. Thus, tick secretion is ineffective at retarding water loss through the cuticle and has no apparent role in tick water balance. The role of the large dermal glands appears to be restricted to semiochemical production, implying that these glands are uniquely modified for this function.