Intraspecific Variation of the Cephalic Labial Gland Secretions in Bombus terrestris (L.) (Hymenoptera: Apidae)

Variations of secretions of the cephalic part of the labial glands from four different subspecies of Bombus terrestris, B. t. terrestris, B. t. lusitanicus, B. t. sassaricus, and B. t. dalmatinus, were investigated. 95 compounds were detected in the whole data set: 54 in B. t. terrestris, 54 in B. t. lusitanicus, 48 in B. t. sassaricus, and 44 in B. t. dalmatinus. The (E)-2,3-dihydrofarnesol is the main compound in B. t. dalmatinus and B. t. sassaricus, while it is dihydrofarnesyl dodecanoate in B. t. terrestris and B. t. lusitanicus. A principal component analysis produced a pattern showing three well distinct groups corresponding to dalmatinus, sassaricus, and terrestris+lusitanicus.