Complexity of Bumble Bee Marking Pheremones: Biochemical, Ecological and Systematical Interpretations

Male bumble bee labial gland marking pheromone blends from 18 species belonging to three genera (Bombus, Pyrobombus and Alpinobombus) are compared from biochemical, ecological and systematical points of view. General chemical similarities within the genera have been found and also distinct characteristics for each species. Male spatial, temporal, mechanical and marking pheromonal premating species-isolating mechanisms are compared between species in a subalpine/alpine area. Species which utilize the same mating habitat usually differ greatly by virtue of their mechanical, pheromonal and, to some extent, temporal characteristics. These mechanisms enhance species discrimination and counteract hybridization

Determination of the Double Bond Position in Monounsaturated Acetates from Their Mass Spectra

A simple method of widespread applicability in determining double bond positions in C12, C14, and C16 straight-chain monounsaturated acetates is presented. The analysis is made with a capillary gas chromatograph coupled to a low-resolution mass spectrometer which is operated in the electron impact mode. No chemical derlvatlzation of the unknowns is needed. Five pairs of selected mass spectral fragments are chosen to distinguish positional isomers. A new mathematical model is introduced which permits simultaneous comparisons of all five ratios of unknowns and references. The method can be used for analyses of very small amounts (<5 ng) of unknown acetates in insect samples

Individual variation in the pheromone of the turnip moth, Agrotis segetum

Female turnip moths (Agrotis segetum) from a laboratory culture inbred for more than 30 generations, and the offspring (first and third generation) from field-collected insects were analyzed individually for acetates and alcohols in the pheromone gland. Quantitative analysis of individual components was performed at the subnanogram level by gas chromatographymass spectrometry (selected ion monitoring). The titer of the pheromone, i.e., the sum of the homologous acetates (Z)-5-decenyl acetate, (Z)-7-dodecenyl acetate, and (Z)-9-tetradecenyl acetate was 2.0 ± 0.3 ng in the laboratory culture and 3.2 ± 0.6 ng in the "wild strain." There was no correlation between pheromone titer and female weight. The relative proportion of the pheromone components varied substantially between individuals, but there was no statistically significant difference between the two populations. The percentages of the respective compounds (-X ± coefficient of variation) were 14.8 ± 127% for Z5-10:OAc, 55.6 ± 32% for Z7-12:OAc, and 29.6 ± 59% for Z9-14:OAc. The pheromone composition varied more in the wild strain than in the laboratory culture. The significance of the pheromone variation to the attraction of males was tested in a field experiment. The ratio of males trapped by the most attractive blend versus the least attractive one was 2.2

Studies on Natural Odoriferous Compounds XXII

A comparison is made between methods for the isolation/enrichment of biologically active odors from Ophrys orchids. The main techniques discussed here are: 1. Direct odor collection (“direct headspace”), 2. Low temperature trapping, 3. Adsorption by enfleurage or by packed precolumn, 4. Strippiug of volatiles in the GC inlet system, 5. Solvent extraction, 6. Steam distillation. The organoleptic examination of thin-layer chromatographic and gas chromatographic fractions has been employed in this work and is briefly described. The further analyses of Ophrya odors were carried out by capillary gas chromatography-mass spectrometry. Four of the isolation methods are preferred. Two of these are accumulation methods (2 and 3), and the other two (4 and 5) give a cross section of the volatile constituents. Any of the six possible combinations of two of these four methods give good results depending on the main objectives of isolation. Characteristics/advantages of the six possible combinations between two of the methods are discussed

MARKING PHEROMONES OF MEGABOMBUS SYLVARUM (L.) AND M. RUDERARIUS (MULLER) MALES (HYMENOPTERA : APIDAE)

International audienc

Sex pheromone components of the turnip moth, Agrotis segetum - Chemical identification, electrophysiological evaluation and behavioral activity

Analysis of female abdominal tips of Agrotis segetum by means of GC-MS showed the presence of 13 aliphatic acetates and alcohols. (Z)-7-Dodecenyl acetate was found to be the main component in the extracts at amounts of about 1 ng/female. (Z)-9-Tetradecenyl acetate and (Z)-7-dodecenol were present to the extent of 49 and 19%, respectively, of the main component. Minor components could be identified as decyl acetate, (Z)-5-decenyl acetate, dodecyl acetate, (Z)-9-dodecenyl acetate, tetradecyl acetate, a tetradecenyl acetate, hexadecyl acetate, a hexadecenyl acetate, (Z)-5-decenol, and (Z)-9-tetradecenol. The presence and biological activity of decyl acetate, (Z)-5-decenyl acetate, and (Z)-7-dodecenyl acetate in the extracts could be detected by GC-EAD. Tested by EAG (Z)-5-decenyl acetate evoked the highest response among pheromone candidates, followed by (E)-5-decenyl acetate and (Z)-7-dodecenyl acetate. Single-cell recordings from 100 male antennal sensilla trichodea revealed receptorcells highly sensitive to (Z)-5-decenyl, (Z)-7-dodecenyl, (Z)-8-dodecenyl, and (Z)-9-tetradecenyl acetate as well as (Z)-5-decenol. The (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetate receptors were activated significantly also by female extracts. When tested in a tube olfactometer, a blend of decyl, (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetate evoked the same male response as did female glands. Tested in the field, this blend was more attractive than virgin females. Other authors previously reported many of the compounds identified in the present study. However, both quantitative and qualitative discrepancies exist among the various investigations, possibly due to the existence of geographical races

Determination of the double bond position in monounsaturated acetates from their mass spectra

A simple method of widespread applicability in determining double bond positions in C12, C14, and C16 straight-chain monounsaturated acetates is presented. The analysis is made with a capillary gas chromatograph coupled to a low-resolution mass spectrometer which is operated in the electron impact mode. No chemical derlvatlzation of the unknowns is needed. Five pairs of selected mass spectral fragments are chosen to distinguish positional isomers. A new mathematical model is introduced which permits simultaneous comparisons of all five ratios of unknowns and references. The method can be used for analyses of very small amounts (<5 ng) of unknown acetates in insect samples