Wild bees also deteriorated due to lack of flowers – GroeneRuimte.nl

The loss of flowers in the landscape could very well could be a major cause of the decline of wild bee species. This had long been suspected, but until now lacked evidence of this. That evidence is provided by means of research on bee pollen from museum collections. Alterra researcher Jeroen Scheper, together with colleagues including the universities of Wageningen, Leiden and Nijmegen examined pollen bees in museum collections. On this basis they could determine which plants for 1950 by bees were used as host plant. They thereby investigated 57 bee species.

“Our study found a clear relationship between the occurrence of bee species and their host plants,” says Scheper in an explanation of the research that has just been published in the scientific journal PNAS. “The population trend of host plants accounts for a major part of the population trend of the related bee species. The preferred planting declining bee species are in the course of time also deteriorated, and prefer planting outgoing bee species are precisely improved. Bees Types flying on plant families which our crops are doing relatively well, while species that are particularly wild plant species have degraded. That fits the trend that we have observed. “

Date and body size also play a role

 Bee species that are active early in the season do relatively better than species that are active later. This is probably because the flower offering in the current agricultural landscape in the Netherlands is that bad in the spring, but later in the season, from July, is limited. Also, the body size of the bees was found to play a role. Scheper “Larger species are harder deteriorated than smaller species, perhaps because they need more food and therefore dependent on a larger flower offerings are..”

Different types of host plants needed

 To reverse the decline of bees, we are not there with the sowing of flowers standard mixtures, as is now widely deployed. “That only offers relief to a limited part of the Dutch bee species.” According to the authors targeted measures are necessary to promote the availability of preferred host plants of different species in the landscape.

For more information, see the article Museum specimens reveal loss or pollen host plants as key factor driving wild bee decline in The Netherlands at the site of PNAS

source:. Alterra Wageningen UR, 25.11.14

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