by Denis Michez, Researcher at Université de Mons, Belgium and contributor to the IUCN RedList assessment for several European bumblebee species.
This month Bumblebees of the World features Bombus brodmannicus, a poorly understood and endangered bumblebee species found in two fragmented populations separated by more than 2,500km!
Latin name: Bombus brodmannicus
Common name/s: None
Colour pattern: Queens, workers and males have two pale whitish-grey bands on thorax, a broad whitish band at top of abdomen and red tail.
Favoured flowers: Eastern population visits a variety of flowers including clovers. Western sub-species specialises on Cerinthe, although will also visit other plants for nectar, particularly the males.
Global region: Palaearctic
Geographic distribution: Europe: France, Italy, Asia: Turkey, Armenia
Conservation status: Endangered (at European level)
In the east B. brodmannicus can be found in north east Turkey and Armenia across the Caucasian mountains, where it can be quite locally abundant. In the West, the subspecies B. brodmannicus delmasi is restricted to high altitudes in the southern French Alps and a small number of nearby locations in Italy. The species is found on southern slopes of the southwestern Alps in subalpine and alpine zones supporting large patches of Cerinthe, its main food plant. The species is active very early in the morning and at sunset.
Bombus brodmannicus distribution map. Credit: Pierre Rasmont & Stéphanie Iserbyt
Last month we talked about how only three species of all bumblebees worldwide are considered as specialists on a particular food plant. Interestingly, the eastern population of B. brodmannicus, located in the Caucasian mountains is a generalist, while the remote subspecies found in certain valleys of the Western Alps (map above), B. brodmannicus delmasi is considered a specialist. This specialism was deduced from field observations reporting a marked preference of the subspecies for Cerinthe minor L. and Cerinthe glabra . Despite the species reliance on pollen from Cerinthe, it is also known to visit other plants such as Calamintha, Cerinthe , Epilobium, Scabiosa, Echium, Nepeta, Knautia and Stachys for nectar. This behavior is particularly relevant for males whose life-cycle is partly offset from the flowering Cerinthe.
The restricted distribution and food specialisation led to an assessment as Endangered in the IUCN Red List of European Bees. Because of its highly specialised foraging requirements and its already localised distribution in a small area of the Alps, the western population seems extremely vulnerable to warming from climate change. On the other hand, the eastern population is rather widespread in the Caucasian region with no apparent food specialisation. It is therefore much less vulnerable to climate change.
Links to further information
Dellicour, S., De Jonghe, R., Roelants, D. and Michez, D. 2012. Oligolectisme de Bombus brodmannicus delmasi Tkalců (Hymenoptera, Apidae): observations et analyses. Osmia 5: 8-11.
Delmas, R. 1976. Contribution à l'étude de la faune française des Bombidae (Hymenoptera, Apoidea, Bombidae). Annales de la société entomologique de France (N.S.) 12: 247-290.
Franzén, M. and Molander, M. 2012. How threatened are alpine environments? a cross taxonomic study. Biodiversity Conservation 21: 517-526.
Franzén, M. and Ockinger, E. 2011. Climate-driven changes in pollinator assemblages during the last 60 years in an Arctic mountain region in Northern Scandinavia. Journal of insect conservation 16: 227-238.
Goulson, D., Lye, G.C. and Darvil, B. 2008. Decline and conservation of bumble bees. Annual Review of Entomology 53: 11.1–11.18.
Iserbyt, S. and Rasmont, P. 2012. The effect of climatic variation on abundance and diversity of bumblebees: a ten years survey in a mountain hotspot. Annales de la Société entomologique de France (N.S.) 48(3-4): 261-273.
IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015.1. Available at: www.iucnredlist.org. (Accessed: 28 May 2015).
Rasmont, P. and Iserbyt, I. 2010-2012. Atlas of the European Bees: genus Bombus. STEP Project. Atlas Hymenoptera. Mons Available at: http://www.zoologie.umh.ac.be//hymenoptera/page.asp?ID=169.
Rasmont, P. and Iserbyt, S. 2012. The Bumblebees Scarcity Syndrome: Are heat waves leading to local extinctions of bumblebees (Hymenoptera: Apidae: Bombus)? Annales de la Société entomologique de France (N.S.) 48(3-4): 275-280.
Tkalcu, B. 1973. Taxonomie von Pyrobombus brodmannicus (Vogt) (Hymenoptera, Apoidea, Bombinae). Acta entomologica bohemoslovaca 70(4): 259-268.
Williams, P.H., Colla, S.R. and Xie, Z. 2009. Bumblebee vulnerability: common correlates of winners and losers across three continents. Conservation Biology 23: 931-940.