Effects of juvenile hormone analogues on larval metamorphosis in the barnacle Elminius modestus Darwin (Crustacea: Cirripedia)

Two analogues of insect juvenile hormones (JH) have been shown to interfere with the development of Elminius modestus Darwin larvae when dispersed as acetone solutions in sea water. Stage VI nauplii metamorphosed to morphologically abnormal larvae which were intermediate in size between the nauplius and cypris stages; although these larvae were cypris-like they apparently retained some nauplius characteristics. Cyprids either metamorphosed to non-attached adults or formed larvae which were larger or morphologically abnormal. There was evidence that the effects may be related to the physiological development of the larvae at time of exposure. These observations appear to be the first report of the induction of size and morphological abnormalities in a crustacean species by analogues of insect JH and resemble those arising from the hormonal imbalance which such compounds induce during the development of holometabolous insects.