Most managed alfalfa leafcutting bee (Megachile rotundata) populations are assessed by providing samples of bee cells collected at the end of the growing season to x-ray diagnosis laboratories. What occurs during the nesting season to affect reproduction is largely unknown. Alfalfa leafcutting bee nests from certain bee boards housed in 16 domiciles in a Utah alfalfa field were sampled weekly throughout the summer. Half of the domiciles had one wall panel removed to allow 1) more light or 2) more light plus air to reach the bee board next to it compared to the same board in other domiciles that were paired controls with all walls intact. The board next to the manipulated area plus 3-6 other boards in the domiciles were sampled. Temperature was monitored across the season, and collected nest cells were reared or x-ray diagnosed. Results show where and when nest cells contained offspring that became adults in the summer, offspring that entered diapause, larvae that were infected with a fungal pathogen, eggs and larvae of various instars that died for reasons unknown, provision masses with no eggs, or parasitoids or kleptoparasites. Statistical analyses were employed to examine the effects of time, location, temperature, and manipulation on resultant nest cell contents.
