Comparison of juvenile hormone and ecdysteroid haemolymph titres in adult worker and queen honey bees (Apis mellifera)

Measurements of both juvenile hormone and ecdysteroid haemolymph titres were made from the same individuals to explore the possibility that there is an interaction between these hormones in the regulation of adult honey bee behaviour and physiology. Queens, egg-laying workers, and workers engaged in brood care (nurses) had low titres of juvenile hormone whereas foragers had significantly higher titres, as in previous studies. In contrast, ecdysteroid titres were undetectably low in both nurses and foragers, higher in laying workers, and higher still in laying queens. Measurements of juvenile hormone titres are consistent with previous findings demonstrating that this hormone regulates worker age polyethism but does not play a typical role in reproduction. Comparison of juvenile hormone and edcysteroid titres suggests that ecdysteroids are not involved in the regulation of age polyethism but may play a role in the regulation of reproduction in honey bees.