Simultaneous determination of juvenile hormone and ecdysteroid titers in the hemolymph of bumblebee prepupae (Bombus hypnorum and B. terrestris).

By means of radioimmunoassays the titer of juvenile hormone and ecdysteroids in the hemolymph was simultaneously determined in single prepupae throughout prepupal development. The concentrations of both hormones increase and show a peak, thereafter the titers fall sharply at larval/pupal ecdysis. Caste-specific differences in the time sequence of titer changes and in the concentration of JH are discussed.