The role of blood meal in the life of haematophagous horse flies (Diptera: Tabanidae)

Background and Purpose: The aim of this study was to prove whether the most abundant species Tabanus bromius L., 1758 in Eastern Croatia is autogenous or anautogenous. Analysis was performed on the ovarioles in the ovaries of 25 females. Materials and Methods: Periodical collections were carried out at localities close to the river Sava: Plesmo (XL 41) and Spačva (CQ 39) in June, July and August 1995. Horse flies were put in 4% formalin solution. In the laboratory female specimens were dissected in 0.9% water solution of NaCl. After dissection ovaries were removed and preserved in 4% formalin solution. Ovaries were then processed through a standard dehydration series of ethanol solutions, cleared in benzene solutions and embedded in paraffin. Sections were cut at 5 micrometers with the Reichert – Jung rotary microtome. The slices were stained following standard staining procedures. Results and Conclusions: The follicles of the ovarioles were mostly in stage I and II of maturation, proving that blood meal is essential for egg maturation. Based on these results we can conclude that the Tabanus bromius is an anautogenous species in the studied area. Shrunk cellular remains of the follicular epithelium in ovarioles are found in the samples collected during July. A second fully finished gonotrophic cycle was not found