Hormonal Regulation of Vitellogenin Biosynthesis in Ticks. In: Harris KF, editor. Advances in Disease Vector Research. New York: Springer; 1994. pp. 1-22. [DOI: 10.1007/978-1-4612-2590-4_1]

Morphological characteristics and developmental changes of the ovary in the tick Haemaphysalis longicornis Neumann

Haemaphysalis longicornis (Ixodida: Ixodidae) is an important vector of transovarially transmitted parasites of the genus Babesia (Piroplasmida: Babesiidae). In the present study, we investigated the morphological characteristics and developmental changes of the ovary of H. longicornis. We show that the ovary of H. longicornis has a single tubular structure and is surrounded by a tunica propria. There is a longitudinal groove along one side of the ovary. During feeding and after engorgement, great changes can be observed in the ovary of H. longicornis and two rapid growth phases can be detected. The number of major protein bands of the ovary is significantly increased from day 3 of feeding and reaches a maximum on the day of engorgement. Therefore, the great diversity of proteins in the ovaries of H. longicornis can facilitate the identification of new targets for vaccine development.

Absence of insect juvenile hormones in the American dog tick, Dermacentor variabilis (Say) (Acari:Ixodidae), and in Ornithodoros parkeri Cooley (Acari:Argasidae)

Synganglia, salivary gland, midgut, ovary, fat body and muscle alone and in combination from the ixodid tick, Dermacentor variabilis (Say), or the argasid tick, Ornithodoros parkeri Cooley, were incubated in vitro in separate experiments with L-[methyl-(3)H]methionine and farnesoic acid or with [1-(14)C]acetate. Life stages examined in D. variabilis were 3 and 72 h old (after ecdysis) unfed nymphs, partially fed nymphs (18 and 72 h after attachment to the host), fully engorged nymphs (2 d after detachment from host), 3 and 72 h old (after eclosion) unfed females, partially fed unmated females (12-168 h after attachment to host) and mated replete females (2 d after detachment from the host). Those from O. parkeri were third and fourth stadium nymphs and female O. parkeri, 1-2 d after detachment. Corpora allata from Diploptera punctata, Periplaneta americana and Gromphadorina portentosa were used as positive controls in these experiments. No farnesol, methyl farnesoate, JH I, JH II, JH III, or JHIII bisepoxide was detected by radio HPLC from any tick analysis while JH III, methyl farnesoate, and farnesol were detected in the positive controls. To examine further for the presence of a tick, insect-juvenilizing agent, Galleria pupal-cuticle bioassays were conducted on lipid extracts from 10 and 15 d old eggs, unfed larvae (1-5 d after ecdysis), unfed nymphs (1-7 d after ecdysis), and partially fed, unmated female adults (completed slow feeding phase) of D. variabilis. Whole body extracts of fourth stadium D. punctata and JH III standard were used as positive controls. No juvenilizing activity in any of the tick extracts could be detected. Electron impact, gas chromatography-mass spectrometry of hemolymph extracts from fed, virgin (forcibly detached 7 d after attachment) and mated, replete (allowed to drop naturally) D. variabilis and fully engorged (1-2 d after detachment) O. parkeri females also failed to identify the common insect juvenile hormones. The same procedures were successful in the identification of JH III in hemolymph of fourth stadium D. punctata. Last stadium nymphal (female) O. parkeri implanted with synganglia from second nymphal instars underwent normal eclosion to the adult. The above studies in toto suggest that D. variabilis and O. parkeri do not have the ability to make the common insect juvenile hormones, and these juvenile hormones do not regulate tick metamorphosis or reproduction as hypothesized in the literature.