The honeybee, Apis mellifera L., is a social insect and they show wide variety of exquisite social behaviors to maintain colony activity. To enable the elucidation of those social behaviors at a molecular level and gene function in the nervous system, we developed an in vivo method to perform gene transfer in the adult brain of living honeybee by electroporation. When green fluorescent protein-expressing plasmid was transferred to the brain with this system, green fluorescence was observed near the anode location. The expression of transfected genes was confirmed at both transcriptional and translational levels by reverse transcription-polymerase chain reaction and immunoblot analyses. This system will facilitate the analysis of gene function and the regulatory mechanisms of gene networks in the nervous system and provide clues to clarify the relation between those genes and the complex behaviors of the honeybee. (C) 2004 Elsevier Inc. All rights reserved.