The effect of shape parameters on maximal detection distance of model targets by honeybee workers

The influence of several spatial parameters on the maximal detection distance of a target by approaching foraging honeybees was examined. The roles of target diameter, color and luminance contrasts have been already demonstrated in earlier studies. The present study used, for the first time, dissected flower like targets that differed in addition to diameter (D) and area (pi(D/2)(2) = Acir) also in the length of contour line (C), the area of the colored "petals" (Acol) and the degree of dissectedness as expressed mainly by the ratio Acol2/C. The color and luminance contrasts were identical for all targets. Our results confirm the importance of size. However, we demonstrate for the first time, that full circular shapes have the greatest maximal detection distance among targets of equal diameters, and even more than dissected targets with equal Acol and double D. The parameter Acol2/C was found as the best predictor of maximal detection distance of vertically presented targets with varying diameter and degree of dissection for honeybee workers. We propose that an increase in the colored area and decrease in contour line is advantageous due to the fact that it increases the amount of contrast that the target as a whole produces against its background.