Effect of Three-dimension and Color Contrast on Nest Localization Performance of Two Solitary Bees (Hymenoptera: Megachilidae)

We addressed the importance of third dimension and color contrast as cues used in close range nest localization by Osmia lignaria Say and Megachile rotundata (F.) females. By manipulating the surface of the nesting site, we compared 3-dimensional configurations of three different depths (1 cm, 2 cm, and 6 cm) and three different color contrasts (black-black, black-gray, and black-blue). We also tested the relative importance of third dimension and color contrast by manipulating both variables. Both species respond to changes in depth as well as in color contrast by increasing searching time and by displaying behaviors consistent with disorientation. Increasing the depth of the 3-dimensional configuration as well as the amount of color contrast led to an increase in the level of confusion.