Hormonal Interference with Pheromone Systems in Parasitic Acarines, Especially Ixodid Ticks.
Annual technical rept. no. 4. 1 May 83-30 Apr 84,
OLD DOMINION UNIV NORFOLK VA DEPT OF BIOLOGICAL SCIENCES
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The most important result of recent project research was the demonstration of the juvenoid JH III by radioimmunoassay. This assay revealed an estimated 78 pgtick in the hemolymph of partially fed Hyalomma dromedarii females, and an estimated 3 pgtick in the hemolymph of partially fed D. variabilis. Other studies, especially digestion of tritium labelled JH III, provided additional evidence suggesting the presence of this hormone in adult ticks. The implications of these findings for our understanding of sex pheromone regulation in ticks is discussed. Other studies described in this report deal with the source of ecdysteroid in teh camel tick, Hyalomma dromedarii, the American dog tick, Dermacentor variabilis, and the soft tick, Ornithodoros parkeri. Studies done at ODU, using radioimmunoassay high performance liquid chromatography, and autoradiography, provide new evidence implicating the tick synganglion - lateral nerve plexus as an important site of ecdysteroid activity in the ixodid ticks. Other studies with ecdysteriods suggest that metabolism of ecdysone or 20-hydroxyecdysone or both to inactive metabolites, possibly including polar conjugates. If confirmed, these findings indicate the presence of only a single active ecdysteriod hormone in ticks, 20-hydroxyecdysone.