Flower Diversity May Mitigate Insecticide Effects on Wild Bees
Published:07 Feb.2021    Source:University of G√∂ttingen

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 (from the neonicotinoid class of insecticides), was available to the bees, this had a negative effect on their reproductive success. However, this negative effect of the insecticide only occurred in cages with oilseed rape monocultures, which suggests that such effects can be mitigated by alternative food resources from species-rich flowering mixtures.