Biochemical and Physiological Studies of Certain Ticks (Ixodoidea). Fatty Acid Composition of Lipids and Free Fatty Acid Fractions of Hemolymph and Gut and Molting Fluids of Nymphal and Female Hyalomma (H.) Dromedarii Koch and H. (H.) Anatolicum Excavatum Koch (Ixodidae)1

Abstract

Total lipid fatty acids (LFA) and free fatty acid (FFA) fractions of the hemolymph and gut and molting fluids of premolting nymphs and engorged and ovipositing females of Hyalomma (H.) dromedarii Koch and H. (H.) anatolicum excavatum Koch (Family Ixodidae) were analyzed by gas-liquid chromatography. Qualitative analysis revealed 20 fatty acids (FA) with carbon chain lengths from C8 to C24. In each state analyzed, palmitic, stearic, oleic and linoleic acids were the major acids and comprised ca 80–90% of the total FA. In each state, LFA and FFA concentration patterns were similar though levels differed in the 2 species. After engorged ticks dropped from the host, the gut fluid FFA and LFA concentrations decreased on nymphal immobilization day and increased on female oviposition day. Total FFA concentrations of nymphal hemolymph increased and LFA decreased on immobilization and waxy days. Hemolymph FFA concentrations sharply increased and LFA concentrations sharply decreased in ovipositing females. Nymphal and female hemolymph and gut fluid FFA and LFA concentrations were much higher than in host (rabbit) plasma or whole blood. In nymphs, molting fluid FFA and LFA concentrations were lower than in hemolymph and gut fluid. Nymphs and females of each species have different requirements for FA utilization and metabolism. Gut fluid LFA in nymphs were metabolized in approximately similar proportions. Results indicate that oleic acid-associated lipids are incorporated in egg formation.