Cholinergic involvement in nervous control of salivary fluid secretion in ixodid ticks

Abstract

1. Approximately one-third of all adult Amblyomma maculatum ticks become bloated with a huge increase in hemolymph volume while feeding on sheep infused with fenthion at the rate of 2.5 mg/kg/day. 2. Almost all other ticks die early and appear severely desiccated while attempting to feed on the same animals. 3. All ticks are loosely attached and the usual inflammation seen at the site of tick attachment is absent. 4. These facts, along with increased haemolymph concentrations of Na +, K + and Cl − in the hemolymph and an inability of pilocarpine to induce salivation in bloated ticks suggest that normal salivary gland function is disrupted. The results support the hypothesis of cholinergic neurotransmitter involvement in the overall nervous control of ixodid tick salivary gland function.