Effect of juvenile hormone on short-term olfactory memory in young honeybees (Apis mellifera)

Reliable retention of olfactory learning following a 1-Ttrial classical con ditioning of the proboscis extension reflex (PER) is not achieved in honeyb ees until they are 6-7 days old. Here we show that treatment of newly emerg ed honeybees with juvenile hormone (JH) has a profound effect on the matura tion of short-term olfactory memory. JH-treated individuals display excelle nt short-term (1 h) memory of associative learning at times as early as 3 d ays of age and perform consistently better than untreated bees for at least the first week of their lives. By contrast, the retention of long-term (24 h) memory following a 3-trial conditioning of the PER is not significantly improved in JH-treated bees. Our study also shows that experience and (or) chemosensory activation are not essential to improve learning performance in olfactory tasks. The lack of accelerated development of long-term retent ion of olfactory memories in JH-treated honeybees is discussed in the conte xt of neural circuits suspected to mediate memory formation and retrieval i n the honeybee brain. (C) 2001 Academic Press.