The Bombus lucorum complex – a study across urban and rural habitats

During summer 2018, Trinity College Dublin undergraduate student, Maeve McCann, carried out a research project using molecular methods to identify individual bumble bees belonging to the Bombus lucorum complex. She wrote a blog about her fieldwork back in July, and now she has completed her project. Here’s what she found…

Summary:

Bumble bees are commercially and ecologically important pollinators. They are declining in Ireland due to climate change, land use change and habitat loss. To inform effective conservation it is vital that species distribution and abundance is known. Four of the most common bumble bees in Ireland, belonging to the Bombus lucorum cryptic complex, require molecular identification through PCR/RFLP digest to distinguish individual species, as morphological characteristics are shared in a cryptic manner.

Our study used molecular techniques to identify bees from the urban and rural settings of Dublin city and County Fermanagh respectively.

We were able to identify a total of 98 individuals, which revealed a unique species composition in each region. In Dublin, individuals were identified as Bombus cryptarum (4.2%), Bombus lucorum (8.3%) and Bombus terrestris (87.5%); and in Fermanagh, Bombus cryptarum (46%), Bombus lucorum (20%) and Bombus terrestris (34%).

No Bombus magnus individuals were found.

Conclusions:

This research project has shown differentiation in the species composition of the B. lucorum complex across a rural and urban setting. The species present varies between each region, but pooled regional data are mostly representative of each site within the region. While the findings show clear regional differences, this difference in species composition could indicate that these species are variable with regard to their preference for a rural or urban environment. However, the extent to which the B. lucorum complex reliably differentiates across all of Ireland can only be assessed by an all-Ireland study controlled for these rural and urban differences. As it stands, B. cryptarum and B. magnus are data deficient, however it could be noted that much of the data on B. lucorum is inconclusive as it too is also deficient on high quality (molecular) identifications.  More investigation is required to understand the ecology of each species uniquely and thus inform conservation strategies.

Download the full report here.

Maeve McCann is an undergraduate Science student at Trinity College Dublin, and her project was supported by the C.B. Dennis British Beekeepers’ Research Trust.