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Action of some steroids on salivary gland degeneration in the ixodid tick, A. americanum L.

1988; Elsevier BV; Volume: 34; Issue: 5 Linguagem: Inglês

10.1016/0022-1910(88)90103-5

1879-1611

Paul J. Lindsay, W. Reuben Kaufman,

Neurobiology and Insect Physiology Research

In female ixodid ticks, autolysis of the salivary gland after the blood meal is triggered by a ‘tick salivary gland degeneration factor’; which is probably an ecdysteroid. In Amblyomma americanum L. the critical weight for the synthesis-release of the degeneration factor is about 60–70 mg. Fluid secretory competence is lost by 3–4 days after engorgement. The following ecdysteroids (all at 1 μg/ml) induce salivary gland degeneration after 4 days in culture in TC medium 199: cyasterone, ecdysone, 20-hydroxyecdysone, muristerone A, polypodine B, ponasterone A, ponasterone C. Vertebrate steroids (cortisol, β-estradiol, progesterone, testosterone) and 2-deoxyecdysone (all at 1 μg/ml) did not induce salivary gland degeneration. Rather, they all significantly improved fluid secretory competence, although the mechanism for this effect is not known. We conclude that the structural requirements for causing degeneration of the salivary gland of Amblyomma americanum are similar to those generally required for ecdysteroid activity in insects.