Hormonal Interference with Pheromone Systems in Parasitic Acarines, Especially Ixodid Ticks.

New evidence which confirms the existence of ecdysterone beta-ecdysone in the ticks Dermacentor variabilis Say and Hyalomma dromedarii Koch is presented. Evidence implicating the occurrence of alpha-ecdysone, in much smaller amounts than that observed for ecdysterone, is also noted. Polar compounds, at least two of which react in the radioimmunoassay for ecdysone, are also present in both species, and are probably metabolites of the active hormones. No consistent relationship was found in the changes in ecdysteroid concentrations during development, maturation or feeding and the onset of sex pheromone activity. However, ultrastructural changes in the foveal glands following exposure to exogenous ecdysterone parallel those seen in females secreting pheromone. Additional evidence of direct excitation of sex pheromone activity was found in H. dromedarii exposed to exogenous ecdysterone or an ecdysterone analog. Studies on the occurrence of genital sex pheromones were continued. Male perception of an excitatory substance detected in the female, presumably near or in the gonopore, is reviewed.