The stomatogastric nervous system of the honey bee (Apis mellifera) in a critical phase of caste development.

Abstract

Progress in our understanding of polymorphic differentiation of female honey bee larvae into queens and workers required a re-evaluation of neuronal pathways potentially involved in transmitting information on food quality. This study presents new data on the anatomy of one of these pathways, the stomatogastric nervous system (SNS) of honey bee larvae and pupae. Scanning electron microscopy preparations demonstrated not only developmental changes in frontal ganglion structure, but also provided firm evidence for a hypocerebral ganglion in the honey SNS. In addition to previously described SNS nerves, the frontal, recurrent and esophageal nerves, and the frontal connectives, we observed three new nerves that connect the SNS to the central nervous system and the foregut. The first one is an unpaired connective nerve of the frontal ganglion to the anteromedial protocerebrum. The second consists of paired lateral branches of the recurrent nerve, and the third is a plexus of fine nervous branches associated with the pharynx. Lateral extensions of the newly described hypocerebral ganglion also make contact with the pharynx. Similar but smaller branches were also observed to originate from the esophageal nerves as they run along the foregut. The exact anatomical localization of the cardiostomatogastric nerves, which connect the SNS with the retrocerebral complex, could also be detected. The description of such new nervous connections will serve as a database for functional analyses on the role of the SNS in differential feeding responses of the honey bee larvae, representing the initial step in caste differentiation. J. Morphol. 236:139-149, 1998. © 1998 Wiley-Liss, Inc.