QUANTITATIVE VARIATION OF 20‐HYDROXYECDYSONE IN THE NYMPH OF DERMACENTOR NIVEUS NEUMANN*

Abstract

The variation of 20‐hydroxyecdysone (20 E) levels in the unfed, feeding and engorged nymphs of Dermacentor niveus was studied. The results showed that 20 E existed in all stages of nymphal development. There were two peaks. A small peak (2. 34 ng/nymph) appeared in the feeding period (5 days after attachment) which was connected with the fast feeding before dropping from the host, and a big peak (16.17 ng/nymph) in the moulting period (8 days after engorgement). The latter might be correlated with epicuticle deposition. From the 6th day to the 8th day after engorgement, the level of 20 E rose rapidly. Apolysis occurred in this period.

ECDYSTEROIDS IN THE LARVA OF HAEMAPHYSALIS LONGICORNIS NEUMANN (ACARI: IXODIDAE)*

“…They are also found in ticks. They are involved in nymphal molting and super molting (Connat et al 1983, Liu et al 1995, terminating diapause of larva and adult (Wu et al 1994), salivary gland degeneration (Ma0 et al. Thereafter, a great deal of works on ECs were conducted.…”

“…U p to now, ECs have been found in ixodid and argsid ticks (Diehl et al 1986, Liu et al 1995. They are involved in nymphal molting and super molting (Connat et al 1983, Liu et al 1995, terminating diapause of larva and adult (Wu et al 1994), salivary gland degeneration (Ma0 et al. 19951, oogenesis inhibition (Connat et al 1983), and sex pheromone production (Dees et al 1984;Liu et al 1997).…”