Mapping of active brain regions in Japanese honeybees that form a 'hot defensive bee ball'
Abstract
Japanese honeybee (Apis cerana japonica) workers exhibit a characteristic defense behavior against giant hornets (Vespa mandarinia japonica) that invade their hives: they form a 'hot defensive bee ball' by surrounding the hornet en masse, thus killing it with heat. In this study, we used a neural activity marker gene, termed Acks (=Apis cerana kakusei), to show that a subpopulation of neurons that comprise the mushroom bodies (a higher brain center) is active in the brains of Japanese honeybee workers that form a hot defensive bee ball. Similar mushroom body neural activity was observed in the brains of workers merely exposed to high temperature in an insect cage in the laboratory, suggesting that high temperature information is processed in the brains of workers that form a hot defensive bee ball.
Paper information
- Title:
- Detection of Neural Activity in the Brains of Japanese Honeybee Workers during the Formation of a ‘Hot Defensive Bee Ball’
- Authors:
- Atsushi Ugajin, Taketoshi Kiya, Takekazu Kunieda, Masato Ono, Tadaharu Yoshida, and Kubo Takeo
- Journal:
- PLoS ONE 7(3): e32902. doi:10.1371/journal.pone.0032902
Fig. 1. Artificial bee ball formation
The hot defensive bee ball is usually formed in the beehive. To collect only the workers involved in forming the bee ball, we inserted a giant hornet suspended on the tip of a wire into a hive (A) to allow the Japanese honeybees form a bee ball around the giant hornet (B), and recovered the bee ball in a glass beaker (C). The decoy hornet inside the bee ball was dead 60 min after formation of the bee ball (D).
Fig. 2. Active brain regions during formation of a hot defensive bee ball
(Left panel) Schematic drawing of the honeybee right brain hemisphere. Acks signals detected in the brains of workers collected 30 and 60 min after the bee ball formation are schematically indicated with black dots. (Right panels) The results of in situ hybridization are shown in panels A and B, which correspond to the red boxes in the left panel. Many dotted Acks signals were detected at 30 (middle column) and 60 min (right column) after the bee ball formation. In contrast, little signal was detected at 0 min (left column). Note that the Acks signals were much more dense in the Class II Kenyon cells (panels B). Bars indicate 100 µm.