Fig. 1. (A) Training arrangement. The outbound and inbound paths of ants are indicated by black and green arrows, respectively. The heavy grey line marks a V-shaped barrier, each arm of which is 6 m long and 5 cm high, enclosing an angle of 120°. A sandy ramp (see B) attached to the inside of the V-shaped array enabled the ants to pass the barrier on their way from the nest N to the feeder F. In the opposite direction, F to N, smooth, light-brown tape glued to the feeder-facing side of the barrier forced the ants to detour around the left (E_l) or right (E_r) end of the barrier. T, central tip of the V-shaped barrier. Lengths of path elements: NF, 13 m; FT, 5 m; TE_l and TE_r, 6 m; E_lN and E_rN, 7.2 m. (B) Transverse section of the barrier. (C) Data analysis. Example trajectory of a zero-vector ant tested with the barrier in the training orientation. The ant was released at T and its path was recorded for 5 min. The following variables were analysed: (i) the walking distance along the barrier immediately before the ant turned around E_r (orange); (ii) the length of the subsequent path segment (green, ‘detour vector’) measured from the intersection of the trajectory with the imagined extension of the barrier until the ant made a sharp turn of more than 90° compared with its preceding running direction (arrowhead); (iii) the angular deviation of the detour vector from a line connecting E_r and the fictive position of the nest relative to the barrier (). For this purpose, the intersections (small circles) of the trajectory of the ant with concentric circles (radii 1, 2, 3 and 4 m) centred on E_r were determined.

Return to article