Showing papers on "Ixodes ricinus published in 1969"

Structure of the Female Reproductive System of Ixodes ricinus (L.), and Its Bearing on the Affinity of Ixodes to Other Ixodid Genera

Abstract: In the female reproductive organs of unfed Ixodes ricinus (L.), 2 oviducts, which emerge from a horseshoe-shaped ovary, enter a common oviduct ("uterus") that opens by a short connecting tube into the dorsal surface of the cervical part of the vagina. A pair of tubular accessory glands arise between the histologically different cervical and vestibular parts of the vagina. Unlike ticks of other ixodid genera, I. ricinus has no separate seminal receptacle. The common oviduct appears to function as a uterus, as in argasids. The histology of these organs is described and compared with that of other ticks. These findings, which provide supporting evidence for concepts of structural and biological differences between the genus Ixodes (Subfamily Ixodinae) and other genera in the Family Ixodidae, should be considered in comparative generic studies of transovarial transmission of tickborne disease agents. Ticks of the genus Ixodes (Subfamily Ixodinae) show several specialized structural and biological patterns differing from those in other ixodid genera (Family Ixodidae). Phylogenetically, they occupy a solitary position as a unique branch from proixodoidea stock (Hoogstraal, 1956). Their lack of eyes is considered to be a primitive feature. Sexual dimorphism is marked, in contrast to other genera. The structure of the testes and of the accessory glands differs significantly from that in other genera, as does the method of integumental splitting during molting (Kahn, 1964). Only in this genus, the anal grooves meet anterior of the anus and the male venter is covered by shields. Biologically, Ixodes is exceptional in the variety of its male-female relationships on or off the host (Nuttall, 1911), in the large number of species comprising the genus, and in the variety of host relationships and ecological and distributional patterns within a single generic assemblage (H. Hoogstraal, pers. comm.). This study of the structure of the female reproductive system in Ixodes ricinus (L.), the best known European species of this genus, provides evidence of a Received for publication 6 June 1969. * From Research Project MF12.524.009-3010, 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. distinct morphological pattern differing widely from the common structure described in other ixodid genera. Comparative investigation of the internal morphology of certain Argas species has resolved views of subgeneric divisions and has permitted correlation of internal and external characters within the subgenera of Argas (Roshdy, 1961, 1962a, 1963, 1966). The reproductive organs of ticks have been studied by Christophers (1906) and Robinson and Davidson (1914) who, while working on Ornithodoros (0.) savignyi (Audouin) and Argas (Persicargas) persicus (Oken), respectively, first used the terminology adopted by subsequent investigators for components of the female argasid genital system (Lees and Beament, 1948; Wagner-Jevseenko, 1958; Roshdy, loc. cit.). The structure of the ixodid female genital organs differs from that of argasids and is similar in all ixodid genera except Ixodes. These organs in Ixodes melicola Schulze and Schlottke were described by Yalvac (1939b). Balashov (1964) reviewed previous work and gave a comprehensive account of the structure and development of the reproductive organs in some tick species, including parts of the female organs of I. ricinus. The female genital pattern described for the ixodid genera Dermacentor (Douglas, 1943), Hyalomma (Yalvac, 1939a; Balashov, 1964), and Rhipicephalus (Till, 1961) is also found in Haemaphysalis and Amblyomma (Roshdy, unpublished).