Hormonal Interference with Pheromone Systems in Parasitic Acarines, Especially Ixodid Ticks.
Annual technical rept. no. 1, 1 May 80-30 Apr 81,
OLD DOMINION UNIV NORFOLK VA DEPT OF BIOLOGICAL SCIENCES
Pagination or Media Count:
Treatment of Hyalomma dromedarii and Dermacentor variabilis with abnormally high concentrations of insect hormones and hormone antagonists did not greatly alter sex pheromone regulated communication in these ticks. Slight reductions up to 20 in the ability of D. variabilis to inseminate the treated females were observed, but the response was not dose related. Precocene was found to be highly toxic to immature ticks and embryos. Disruption of the gonadotrophic cycle was complete in females which developed from embryos treated on the day of oviposition, and partial disruption was found in those treated later in embryogenesis. Application of juvenile hormone JH to females previously treated with Precocene resulted in restoration of gonadotrophic function, suggesting the possibility of a naturally occurring JH in these ticks. The identify of the sex pheromone of Hyalomma dromedarii and H. excavatum 2, 6-dichlorophenol, was confirmed by gas chromatography and bioassay of the pheromone containing fractions. Unfed H. dromedarii females had 1.03 ngtick unfed H. excavatum females had 0.25 ngtick. No 2, 6-dichlorophenol was found in fed H. dromedarii males. In addition to this general ixodid pheromone, evidence of another species-specific chemical mechanism minimizing interspecific mating was discovered. Tests to determine the effects of exogenous hormone treatments must consider alterations in the entire sequence of mate-seeking responses, since the effects may be limited to alterations of only one of the controlling chemicals. Primordia of the foveal glands, or sex pheromone glands, were found in the engorged nymphs of H. dromedarii.
- Anatomy and Physiology