Biochemical and Physiological Studies of Certain Ticks (Ixodoidea). Osmotic Pressure of Hemolymph and Gut and Coxal Fluids during the Gonotrophic Cycle of Argas (Persicargas) persicus (Oken) and A. (P.) arboreus Kaiser, Hoogstraal, and Kohls (Argasidae)

Abstract

The osmotic pressure (OP) of the hemolymph and gut and coxal fluids of female Argas (Persicargas) persicus and A. (P.) arboreus were determined in different states of the gonotrophic cycle (unfed + 2 and + 15 days, engorgement day before and after coxal fluid emission, engorgement + 1 day, oviposition day, and oviposition completion + 1 day). OP patterns in both species were much alike. Hemolymph OP after coxal fluid emission following engorgement decreased to a minimum (155.43 and 161.00 mx/liter NaCl in persicus and arboreus, respectively), then increased to a maximum on oviposition completion + 1 day (227.10 and 245.50 mM/liter in persicus and arboreus, respectively). The gut fluid OP after feeding increased significantly in persicus on engorgement day after coxal fluid emission, but it increased in arboreus only on engorgement + 1 day. The gut fluid OP of both species decreased after oviposition almost to the initial level in the unfed state. In both species, coxal fluid was isosmotic with hemolymph after coxal fluid emission on engorgement day. The hemolymph OP in both species was higher than that of the gut fluid in each state tested except on engorgement day and engorgement + 1 day. Tick tissues and organs are bathed in hemolymph. Thus hemolymph properties affect the biochemical characteristics of the entire tick organism as well as its vector potential. In a previous study (Hefnawy, 1972), the hemolymph volume of Argas (Persicargas) persicus (Oken) and of A. (P.) arboreus Kaiser, Hoogstraal, and Kohls was investigated during the gonotrophic cycle. Osmotic pressure (OP) has an important role in exchange of water and dissolved materials between the cell and its environment. In the present work, changes in OP of the hemolymph and gut and coxal fluids of these species were investigated durReceived for publication 25 July 1972. * Request reprints from Medical Zoology Department, NAMRU-3, U. S. Interests Section, c/o Spanish Embassy, Cairo, Arab Republic of Egypt. t From Research Project MF12.524.009-3010B, Bureau of Medicine and Surgery, Department of the Navy, Washington, D. C. The opinions and assertions contained herein are the private ones of the author and are not to be construed as official or as reflecting the views of the Department of the Navy or of the naval service at large. This work was supported in part by Agreement 03-016-1 between the NIAID (NIH) and NAMRU-3. ing the gonotrophic cycle. No study of this kind has previously been made on bloodsucking arthropods. The results may contribute essential knowledge to the search for an efficient tick tissue culture medium. MATERIALS AND METHODS Newly molted female A. (P.) persicus and A. (P.) arboreus were from the same sources and reared under the same conditions as in Hefnawy (1972) and, similar to the previous study, the states tested were unfed + 2 and + 15 days after molting, engorgement day (before and after coxal fluid emission), engorgement + 1 day, oviposition day, and oviposition completion + 1 day. Hemolymph samples were obtained as in Hefnawy (1972), and gut and coxal fluids as in Araman and Said (1972). All samples were centrifuged before testing. The OP of hemolymph and gut content was determined by the method of Gross (1954) with certain modifications. The method consists of placing frozen samples of the test fluid and reference standards of known concentration in capillary tubes in a chilled bath. The bath is warmed slowly and steadily, and the samples melt according to their osmotic concentrations. A standard curve is constructed by plotting the melting time of standards against their concentrations. Standards are distilled water and NaCl concentrations of 100, 200, 300, 400, 500, and 600 mM/liter. Test fluids and standards are drawn in l-,uliter quantities in