The nesting of Osmia rufa (L.) (Hymenoptera, Megachilidae) in the Crimea: Structure and composition of nests

The impact of nest tube dimensions on reproduction parameters in a cavity nesting solitary bee, Osmia bicornis (Hymenoptera: Megachilidae)

“…Although all length classes were used by the bees in our study, the shorter ones (70 and 100 mm) were occupied later than the longer ones, indicating a preference for deeper nest tubes. This result is consistent with increasing frequencies of occupation of reed tubes up to 230 mm depth (Ivanov 2006), but only partly consistent with the preference of 120-mm tubes over both 140-and 100-mm tubes (Maddocks and Paulus 1987).…”

“…The lower acceptance of 4 mm tubes could be a body size exclusion phenomenon. In contrast to the low diameter discrimination in our study, O. bicornis females preferred in other studies either narrow nest diameters of 5-6 mm (Free and Williams 1970;Tasei 1973;Brechtel 1986) or wider nests of 7-9 mm (Jacob-Remacle 1976; Maddocks and Paulus 1987;Ivanov 2006). This inhomogeneity of preferred diameters reflects the diversity of bee body size found in autochthony and managed populations.…”

“…However, the impact of tube length can be expected to diminish above a critical number of brood cells. Females construct a few brood cells for sons at the entrance of the nest (e.g., Raw 1972;Maddocks and Paulus 1987;Ivanov 2006). Therefore, short tubes limit the space left over for the construction of brood cells for daughters.…”

“…This location provides a high diversity and stable richness of food plants. Effects of resource shortage or extensive traveling costs on maternal investment can be excluded (Kim 1999;Ulbrich and Seidelmann 2001;Ivanov 2006;Peterson and Roitberg 2006). Beside the test block, additional nesting tubes of Japanese knotweed (various dimensions) and wooden nest blocks (tube dimensions 8×150 mm, 100-120 tubes per block) were offered in one and the same shelter that protected the nest material from rain and direct sunshine.…”

“…Statistical analysisNesting females adapt the progeny sex ratio and progeny body size to their age-specific provisioning capability (Torchio and Tepedino 1980;Ivanov 2006;Seidelmann 2006). To take these shifts into statistical account, the relative season date for each nest was determined as mean of start and closure dates (see electronic supplementary material for details) and normalized to a total nesting period of 50 days.…”