Evidence of controlled corpus allatum activity in the adult Colorado potato beetle

The in vivo control of corpus allatum (CA) activity in females of Leptinotarsa decemlineata was investigated. Evidence was obtained that CA activity is adjusted by negative feedback when juvenile hormone (JH) titres are changed experimentally. Conclusions are based on determination of the rate of in vitro JH synthesis by the CA, on changes in CA volume, and on JH titres in the haemolymph. These assay methods are used alternatively in some of the experiments.After unilateral allatectomy, the remaining CA had doubled its activity 7 days later. On the other hand, the activity of CA in young adults was suppressed after the JH titre was elevated by the implantations of 2 CA taken from active females. Similarly, in beetles treated topically with exogenous JH the CA atrophied and showed a much reduced activity after 5 days. Denervation of CA in 0-day-old long-day and 7-day-old short-day females did not change CA activity when measured 1 day later.