抄録
The female of the subsocial shield bug, Parastrachia japonensis, provisions food to her nymphs using path integration, a type of navigational strategy that acquires information indicating the traveler's direction and distance. In this study we investigated whether and how P. japonensis females use a light compass involved in orientation at a constant angle with respect to a light source. First, we let the female run toward its burrow in an experimental room when a lamp set on the floor was turned on. Then, we changed the direction of the light source 180° horizontally by switching off the lamp and turning on another lamp on the opposite side. In response to this change, the homing bug turned back immediately. Next, we examined the effects of the light source from two different elevations. It accomplished its path integration task when the light was placed at an azimuth of 45°. When the light was at the zenith (90°), however, the bug lost the correct home direction. These results suggest that in their path integration system P. japonensis use light sources as compass references and, further, that they can estimate their direction from a point located at mid-sky but not the zenith.
