Studies on the regulation of the juvenile hormone titre in bumblebee workers, Bombus terrestris

Abstract

The synthesis of juvenile hormone (JH) by corpora allata (CA) in vitro was studied in queenright and queenless workers during the first 5 days after emergence. In queenless workers the activity of the CA is strikingly higher than in queenright workers, the first differences were observed on the very first day of adult life. The synthetic activities of the CA correspond fairly well with the JH titre obtained by Galleria bioassay. Since the excretory rate was not found to be lower in queenless workers, it is postulated that the increased JH titre is caused mainly by higher activities of CA. The activity of the CA for its part depends upon the presence or absence of a queen. It is shown by HPLC determination as well as by Galleria bioassay that only JH III is produced in vitro.