Labial gland marking secretions of male Bombus lucorum bumblebees from Europe and China reveal two separate species: B. lucorum (Linnaeus 1761) and Bombus minshanicola (Bischoff 1936)

Differences in male bumblebee labial gland secretions can be used to separate species pairs. Cephalic labial gland secretions from male Bombus lucorum Linnaeus bumblebees from Europe, and male ‘B. lucorum’ bumblebees from China, were analyzed by gas chromatography/mass spectrometry (GC/MS). In the European B. lucorum L., ethyl tetradec-9-enoate was identified as the major compound (58% peak area), along with a complex mixture of straight-chain alkenols, acetates, hydrocarbons, and wax type esters. In contrast, the main component of the labial gland secretions of the Chinese ‘B. lucorum’, ethyl dodecanoate (31%), did not dominate the secretion, which additionally contained large amounts of 3,7,11-trimethyldodeca-6,10-dien-1-ol (=2,3-dihydrofarnesol, 24% peak area), ethyl octadec-9-enoate (15% peak area) and a mixture of acyclic diterpenes (alcohols, aldehydes, and acetates). Furthermore, in B. lucorum, 3,7,11-trimethyldodeca-6,10-dien-1-ol was only detected in trace amounts (0.05%) and ethyl octadec-9-enoate corresponded to only 0.8% of the mixture. These results indicate that ‘B. lucorum’ from China is a separate taxon from B. lucorum L. Further analysis revealed that ‘B. lucorum’ from China has been previously described as Bombus minshanicola Bischoff 1936 from Gansu/China. Differences in the chemical composition of male bumblebee labial gland secretions are discussed in comparison with other known bumblebee species pairs.