Red mason bees are important for both ecological and economic reasons.
A higher diversity of flowering plants increases the breeding success of wild bees and may help compensate for the negative effects of insecticides. This is what researchers from the Universities of Göttingen and Hohenheim, as well as the Julius Kühn Institute, have found in a large-scale experimental study. The results have been published in the scientific journal Ecology Letters.
In their experiment, the researchers investigated how successfully the wild bee Osmia bicornis (red mason bee) reproduced. Red mason bees are important for both ecological and economic reasons. The wild bees were experimentally kept in more than 50 large enclosure cages with flower mixtures of varying wild plant diversity and insecticide-treated oilseed rape. Subsequently, the reproductive success of the wild bees, as measured by the number of their brood cells and emerged offspring, was investigated over several months.
The research team found that the number of cells that the wild bees created for their offspring where species-rich flowering mixtures were available was twice that of wild bees where only oilseed rape was available. The reproductive success of the wild bees, which have to supply their offspring with pollen and nectar, increased both in cages with a large diversity of flowering plants and where there were particularly important plant species. In contrast, if oilseed rape treated with clothianidin, was available to the bees, this had a negative effect on their reproductive success.
The study shows that both the diversity of flowering plants and exposure to insecticides significantly influence the reproductive success of wild bees, and shows that a high diversity of flowering plants could compensate for the negative effects of insecticides.
