Palp-splaying Behavior and a Specific Mouthpart Site Associated with Active Water Vapor Uptake in Amblyomma Americanum (Acari: Ixodidae)

Ticks actively absorb water vapor from unsaturated air via their mouthparts. A wax technique was used to cover select areas of the mouthparts of the lone star tick, Amblyomma americanum (L.), to examine whether a specific site is involved in uptake. Covering dorsal, ventral, and distal regions failed to inhibit uptake, whereas wax applied to the proximal region, specifically the hypostome-cheliceral junction, blocked water absorption. A novel occurrence of a palp-splaying behavior was observed during hydrating conditions (93% RH), while ticks were motionless, compared with those held at desiccating conditions (63% RH), which were more active and the palps were not splayed.