Effect of topical application of a juvenile hormone mimic on the duration of the moulting cycle in fifth instar Rhodnius

Fifth instar Rhodnius prolixus given a single topical application of synthetic juvenile hormone (JH) on one of the first 12 days after feeding showed a sigmoid relationship between day of treatment and duration of the moulting cycle. A similar relationship was observed between day of treatment and mean ‘juvenile score’ in subsequently emerging insects. The linear relationship between mean ‘juvenile score’ and duration of the moulting cycle suggests that the increased time from feeding to ecdysis for late-treated insects is a result of the morphogenetic effects of the JH treatment. Some of the partially juvenilized insects obtained by treatment after day 5 produced an odour characteristically detected only from adult insects. The possible significance of this observation is discussed.