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Males of Bombus terrestris (L.) adopt a patrolling behaviour during their nuptial parade using cephalic labial gland (CLG) secretions containing sexual pheromones to attract conspecific virgin queens. The changes in chemical composition of their CLG secretions with age are quite well known. In this study, we investigate the evolution of CLG secretions with age in greater detail and compare behavioural reactions of conspecific virgin queens to the secretions. We show that compounds of CLG secretions follow two profiles. Most of the compounds increase from the first day after emergence until the bees are 15-days-old and then decrease. Others are less abundant in 1 to 15-day-old males and then increase (e.g. tricosane, tricosene, henicosane, tetradecanoic acid, pentacosene, pentacosane, heptacosene, heptacosane, nonacosene and geranylcitronellyl tetradecanoate). Differences in secretion composition lead to preferences of virgin queens for males according to the male’s age. Virgin queens prefer the pheromonal gland secretions of bees of the following ages in decreasing order; 1 day = 3 days < 7 days = 30 days < 15 days < 10 days. The virgin queens are strongly attracted by secretions containing high amounts of 2,3-dihydrofarnesol, 2,3-dihydrofarnesal, ethyl dodecanoate and hexadecanol. On the contrary, geranylcitronellol is more abundant in 30-day-old males.

International audience; The diterpene neocembrene A or (1E,5E,9E,12R)-1,5,9-trimethyl-12-(1-methylethenyl)-1,5,9-cyclotetradecatriene, known as the trail-following pheromone of the advanced Termitidae Nasutitermitinae Nasutitermes exitiosus and Trinervitermes bettonianus, has been identified after SPME-GC/MS as the major component of the trail-following pheromone of the Rhinotermitidae Prorhinotermitinae, Prorhinotermes canalifrons and P. simplex. In all the other Rhinotermitidae studied until now, the major component of their trail pheromones is dodecatrienol ((3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol). This biochemical data further add to the anatomical and molecular characteristics that give a special status to the taxon Prorhinotermes among Rhinotermitidae. In Prorhinotermes canalifrons and P. simplex, neocembrene A was the only secretory compound specific to the sternal gland surface that could be detected after SPME. It elicited orientation as well as recruitment behavioral effects. However, the comparison of the respective biological activities triggered by neocembrene A and by sternal gland secretion suggests that minor components of the latter are acting in synergy with neocembrene A.

The biosynthetic pathway of the formation of males'marking pheromones of two bumblebee species, Bombus lucorum and B. lapidarius, was studied for the first time. After applications of deuterium labelled palmitic acid ([2H31]-hexadecanoic acid) into either the head capsules or abdomens the corresponding deuterium labelled pheromone components were detected in the labial gland (LG) extracts of males of both species. In B. lucorum, ethyl [2H29]-hexadec-9-enoate and ethyl [2H31]-hexadecanoate were identified. No deuterium-labelled ethyl tetradecenoate, that would correspond to shortening of the carbon chain, was detected. In B. B. lapidarius, [2H31]-hexadecan-1-ol and [2H29]-hexadec-9-en-1-ol were found in the LG. Furthermore, the deuterium labelled precursor was incorporated into triacylglycerols (TAG) of the fat bodies of males. In vitro incubation of the labial glands of B. lucorum males with deuterium-and 13C-labelled palmitic acid lead to the formation of saturated ethyl esters only.

The compositions of 23 monoterpene hydrocarbons of six pine species (Pinus sylvestris, P. yunnanensis, P. armandii, P. tropicalis, P. cubensis and P. caribaea) were compared, using multivariate data analysis. Four of the six species were clearly different from the other species in a Principal Components Analysis (PCA) model, based on the relative amounts (selective normalization) of the monoterpenes. The correlation coefficients between constituents were determined separately for each species and the strongest correlations were found between (+)-α-pinene and (+)-camphene and between the corresponding (—)-enantiomers, in all species. This pattern, i.e. a good correlation in all species, was neither shown by the correlation of the structurally more similar (+)-α/β-pinenes, nor by the (—)-α/β-pinenes or within the enantiomeric pairs of α-pinene and β-pinene. For these pairs of monoterpenes, good correlations were found in some species. None of the species showed good correlations in all the investigated monoterpene pairs presented here. Correlations between monoterpenes in insect-attacked trees (P. cubensis and P. caribaea, attacked by Dioryctria horneana, and P. yunnanensis, attacked by Tomicus piniperda) were also determined. The results are discussed from chemotaxonomic and biosynthetic points of view.

Frontal gland secretions of termite soldiers of the speciesNasutitermes costalis, N. ephratae, N. nigriceps, N. rippertii, andN. hubbardii were analyzed. The chiral compositions of the monoterpene hydrocarbons were investigated by means of two-dimensional gas chromatography. Two of them, 3-carene andβ-pinene were present in the form of (−)-enantiomers of high purity in the majority of the samples. The other monoterpenes,α-pinene, camphene, sabinene, limonene, andβ-phellandrene, exhibited a great variation in the enantiopurity between different species.α-Pinene and limonene varied significantly even between different colonies within the species.N. costalis was the only species with an invariable composition of the secretion, independent of the locality or origin.