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]

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.Bombus sylvarum sylvarum / Bombus ruderarius ruderarius / Bombus ruderarius montanus / sexual pheromone / cephalic labial gland secretion / chemosystematics

Notes on distribution of Bombus cryptarum (Hymenoptera, Apoidea) in Moravian territory (Czech Republic) and its laboratory rearing

“…Determination using pheromones (Urbanova et al, 2001;Terzo et al, 2005;Rasmont et al, 2005) was possible in males from laboratory rearing and was carried out by the Institute of Organic Chemistry and Biochemistry (IOCB) of the Academy of Sciences of the Czech Republic in Prague.…”

Comparison of Age-dependent Quantitative Changes in the Male Labial Gland Secretion of Bombus Terrestris and Bombus Lucorum

“…The composition of male sex pheromones of closely related species partially overlap, but have often one specific component and different blend proportions. Currently, the composition of male cephalic gland secretion is used as the most efficient tool for taxonomic identification, species and subspecies discrimination (Paterson, 1985;Terzo et al, 2005;Rasmont et al, 2005;Coppée et al, 2008). However, a great individual variability in the production of pheromonal components was observed within a single species (Svensson and Bergström, 1977;Ågren et al, 1979;Šobotník et al, 2008), which makes taxonomic application sometimes a difficult task, especially in related species.…”

Subspecific differentiation in male reproductive traits and virgin queen preferences, in Bombus terrestris

“…When exposed to B. ignitus CLGS, the B. terrestris dalmatinus females reacted abnormally: they walked endlessly and erratically around the arena, exhibited stress behaviour (they reacted by getting excited, buzzing and walking very quickly), instead of exploring the arena and as observed in other interspecific comparisons in bumblebee species (Calam 1969;Terzo et al 2005). Between B. terrestris subspecies, our comparative analyses show that all B. terrestris subspecies have specific CLGS, as previously observed for all taxa except B. terrestris canariensis (these results are congruent with previous studies; Coppée et al 2008;Lecocq et al 2013b).…”

“…The CLGS are species-specific complex mixtures (mainly aliphatic compounds) dominated by few compounds with a higher concentration (main components) (Calam 1969;Svensson 1979), produced de novo by cephalic labial glands (Žáček et al 2013). CLGS locale variations have been observed among widespread bumblebee species (Terzo et al 2005;Lecocq et al 2013a), especially in Bombus terrestris (L.) Lecocq et al 2013b). However, the consequences of this interspecific differentiation on the premating recognition remain mainly unknown (but see Ings et al 2005).…”