Changes in lipids of the salivary glands of the lone star tick, Amblyomma americanum, during feeding.

The lipid composition of salivary glands from male and female lone star ticks, Amblyomma americanum, was investigated at progressive stages of tick feeding. The amounts of fatty acids from both phospholipid and neutral lipid fractions increased dramatically during the initial stage of feeding and peaked in partially fed females weighing 100-250 mg. Percentage compositions of myristic (14:0) and palmitic acid (16:0) decreased, but stearic (18:0), oleic (18:1), linoleic (18:2), and arachidonic acid (20:4) increased during tick feeding. Arachidonic acid, the precursor to eicosanoids including the 2-series of prostaglandins, increased from 1.3% of all fatty acids in salivary glands from unfed female ticks to 8.2% in salivary glands from fully engorged female ticks. Arachidonic acid was found in the triglyceride fraction of unfed and fed virgin females but only in phosphatidylcholine and phosphatidylethanolamine from salivary glands of other fed female ticks. Comparisons between fed and unfed male ticks and fed/virgin, fed/mated, and unfed females demonstrate that feeding is necessary for accumulation of arachidonic acid in salivary gland phospholipids.