Apidologie 36 (2005) 85-96
DOI: 10.1051/apido:2004072

Intra and interspecific variability of the cephalic labial glands' secretions in male bumblebees: the case of Bombus (Thoracobombus) ruderarius and B. (Thoracobombus) sylvarum [Hymenoptera, Apidae]

Michaël Terzo^a, Klara Urbanova^b, Irena Valterova^b and Pierre Rasmont<sup>a

a</sup>  Laboratory of Zoology, University of Mons-Hainaut (UMH), 6 avenue du Champ de Mars, 7000 Mons, Belgium
^b  Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Praha 6, The Czech Republic

(Received 8 January 2004 - Revised 28 May 2004 - Accepted 25 June 2004; Published online: 16 March 2005)

Abstract - According to the species recognition concept of Paterson, the analyses of the secretions of the cephalic parts of the male labial glands confirm the conspecificity of Bombus (Thoracobombus) ruderarius ruderarius and B. (T.) r. montanus populations from the Pyrenees. These secretions were compared in B. ruderarius and B. sylvarum. We identified the same 7 major compounds as previously known for these species. We also identified 69 minor compounds. These minor compounds emphasise the close relationship between both species. Principal Component Analyses (PCA) were carried out on standardised peak areas of GC-MS chromatograms. The first PCA component is discriminant and shows no overlap between both species. Their secretions differ mostly by the relative concentration of their compounds rather than by their qualitative composition. On the contrary, PCA is unable to separate montanus from ruderarius. The larger variance in the secretions of B. ruderarius results from the very low concentration of the main compound (9-hexadecenol) in some specimens.

Key words: Bombus sylvarum sylvarum / Bombus ruderarius ruderarius / Bombus ruderarius montanus / sexual pheromone / cephalic labial gland secretion / chemosystematics

Corresponding author: Michaël Terzo michael.terzo@umh.ac.be

© INRA, DIB-AGIB, EDP Sciences 2005