Increased overwintering temperature reduces the reproductive success of solitary bees

Wild bees play a key role as pollinators of wild plants and crops, but they are increasingly at risk through anthropogenic global change, such as climate warming. However, how increased temperature during overwintering of solitary wild bees affects their reproductive success remains largely unknown. In a semi-field experiment, we assessed the individual life-long reproductive success of 144 marked females of solitary bee species Osmia bicornis that have been wintered at 0°C, 4.5°C, and 8°C. Overwintering mortality of bees was on average 32% higher at winter temperatures of 8°C compared to 4.5°C or 0°C, at which almost all bees successfully hatched. Moreover, female bees wintered at 4.5°C and 8°C produced less offspring than those overwintered at 0°C (26% or 36% less offspring, respectively). Longevity or daily offspring production rate was not significantly affected by overwintering temperature. However, the nesting duration of females wintered at 0°C tended to be longer (+2.5 days) tha..., Overwintering of solitary bees under controlled conditions:
Solitary bee (Osmia bicornis) females were overwintered under controlled conditions at three different temperature treatments: 0°C, 4.5°C, and 8°C.
Semi-field experiment to assess consequences on the reproductive success of hatched female bees:
To study the consequences of overwintering temperatures on fitness-related parameters, a semi-field experiment using flight cages was conducted with hatched bees. From the day of release until the last bee was observed in the flight cages the number of females roosting inside the nesting units during the night was counted as an estimate of females alive inside each cage. This data was also used for the estimation of longevity (i.e., the time from hatching until the bee was last observed alive). Longevity data was complemented by analysis of recorded videos. Software analysis of video recordings was used to link individual nests with produced brood cells (offspring) to individual females...., , # Increased overwintering temperature reduces the reproductive success of solitary bees

[https://doi.org/10.5061/dryad.3tx95x6pt](https://doi.org/10.5061/dryad.3tx95x6pt)

## Description of the data and file structure

The Excel file \"DATA Mueller et al. Overwintering Temperature Affects Bee Reproduction\" contains the data used for the analyses presented in:

Increased overwintering temperature reduces the reproductive success of solitary bees by Sarah Müller, Jana Collatz, Henning Richter, Robert Zboray, and Matthias Albrecht

Corresponding author: Matthias Albrecht: [[e-mail]](mailto:[e-mail])

The Excel data file contains several sheets. The first sheet is a Read Me file describing all variables used in the different sheets containing different sets of data used for the analyses. The sheet \"hatching rate\" contains all relevant data for the analyses of hatching rate and emergence duration of bees; the sheet \"weight\" contains the...