Effects of the nonsteroidal ecdysone mimic RH 5849 on larval crustaceans

The effects of the nonsteroidal ecdysone mimic RH 5849 on larvae of a crab (Rhithropanopeus harrisii) and the cypris larva of a barnacle (Balanus amphitrite) have been investigated. Larvae were exposed to exogenous RH 5849 in the concentration range of 0.1–10.0 mg/L. The two lowest concentrations tested (0.1 and 1.0 mg/L) accelerated molting of crab zoeae. RH 5849 did not induce premature apolysis. A concentration of 10 mg/L RH 5849 was toxic to zoeae: these larvae underwent apolysis but not ecdysis and subsequently died. Attachment and metamorphosis of barnacle cyprids was enhanced by 10.0 mg/L RH 5849. Increased attachment may be a result of physiological aging of larvae by the ecdysone mimic. Increased metamorphosis is consistent with the stimulatory effect of 20‐hydroxyecdysone on this process. RH 5849 was first demonstrated as an ecdysone mimic in insects (Wing, Science, 241:467–469, '88). The present study provides preliminary evidence for a similar action in crustaceans. © 1992 Wiley‐Liss, Inc.