The role of dietary breadth in national bumblebee (Bombus) declines: Simple correlation?

Bumblebee species declines have been reported in Europe, North America and Asia. Loss of suitable habitat to agricultural intensification is considered to be the main cause of declines in Europe. Differential impacts on species have been recorded but insufficient knowledge of species ecology means that effective conservation management prescriptions cannot be put into place with certainty. Dietary specialisation, specifically on flowers of Fabaceae, has been hypothesised as driving differential declines but the reliability of previous studies has been questioned. Here we present a three-year study of the foraging behaviour of two UK Biodiversity Action Plan bumblebee species. For the first time, analysis of nectar and pollen foraging was performed on sites where nationally rare UK bumblebees were as abundant as more nationally ubiquitous species. Results indicated that the nationally rare Bombus sylvarum collected the majority of its pollen from flowers of Odontites verna and had a significantly narrower mean nectar dietary breadth than ecologically similar species Bombus humilis and Bombus pascuorum (p = 0.004 and 0.008 respectively). In contrast, the dietary breadth of the nationally rare B. humilis was similar to the more nationally ubiquitous species B. pascuorum and Bombus lapidarius. Moreover, B. lapidarius was recorded as having the narrowest pollen dietary breadth, collected pollen from the least number of floral taxa and was the most specialised of the Bombus species on pollen of Fabaceae. Patterns of dietary specialization were inconsistent with national declines and results highlighted a need for further detailed investigation into the factors contributing to differential declines.

University of East London: the 2015 biodiversity update

In May 2012 the Rio+20 summit confirmed a 30% global decline in wildlife since 1970. Following on from the United Nations (UN) International Year of Biodiversity in 2010, global declines in biodiversity have never had such high profile. Rio+20 has been billed as a chance for world leaders to put global society on a sustainable path and an opportunity for the world to get serious about the need for development to be sustainable (Black 2012). For development to be truly sustainable this must include conserving, on a landscape scale, the valuable ecosystem services that biodiversity provides (TEEB 2010). Not only does this mean protecting and enhancing natural and semi-natural landscapes, but also restoring green and blue infrastructure of high biodiversity value in urban areas. As such, rather than merely targeting conservation efforts across the broader countryside, biodiversity also must be returned to our cities, towns and suburbs by breaking up expanses of hard impermeable surfaces and creating niches within which nature can take a hold.