Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)



Committee Chair(s)

Frank J. Messina


Frank J. Messina


Jordi Bosch


Carl D. Cheney


James W. Haefner


William P. Kemp


Theresa L. Pitts-Singer


The visual and olfactory cues used in short-range orientation, specifically nest location and nest recognition, were studied in two solitary bee species Osmia lignaria Say and Megachile rotundata (F.) Osmia lignaria, the blue orchard bee, is an important pollinator of orchard crops, such as apples, cherries, and almonds; and M. rotundata, the alfalfa leafcutting bee, is used in commercial pollination of alfalfa. The general objective was to better understand how these two species locate their nests and how improving nest location could benefit crop pollination.

The use of proximal visual landmarks at the nesting site was investigated with M. rotundata, and revealed that females rely more on vertical landmarks than on horizontal landmarks for nest location. Osmia lignaria and M. rotundata were also shown to use 3-dimensional patterns as well as color contrast patterns for nest location. Changing the depth of the 3-dimensional pattern and the color contrast brightness affected nest location ability of both species. Applying these results to commercial situations with M. rotundata showed that providing 3-dimensional patterns to commercial nesting boards, either by separating the boards or by designing 3D boards, allowed M. rotundata females to improve their nest location. The 3D board also decreased the incidence of chalkbrood-related mortality, caused by the fungus Ascosphaera aggregata. Finally, in-nest observations showed O. lignaria females marking their entire nest with abdominal secretions. These secretions provided olfactory cues that O. lignaria females use for individual nest recognition. A chemical analysis of the nest markings revealed the presence of free fatty acids, long chain hydrocarbons, and wax esters.

These results have implications for commercial bee management practices, where visual and olfactory cues can be manipulated. Improving the nest location performance of M. rotundata and O. lignaria females would decrease nest location time, thus having important consequences on pollination efficiency and brood production of both species.