Comparative study by electrophysiology of olfactory responses in bumblebees (Bombus hypnorum andBombus terrestris)

Electrophysiological data (EAG) were recorded on adult bumblebees stimulated with floral and/or pheromonal pure odorants at different concentrations. The responses of queen, worker, and male bees are compared and the sensitivities of these insects to the pure odorants tested are discussed.

Mandibular gland secretions of two parasitoid wasps (Hymenoptera: Ichneumonidae)

Males ofRhyssa persuasoria andMegarhyssa nortoni nortoni exhibit marked aggregation behavior prior to and during the emergence of females from host trees, and this has been linked with the secretion of an odorous liquid from the mandibular glands. The volatile components of these secretions were examined by combined gas chromatography-mass spectrometry. While both species contained 6-methylhept-5-en-2-one,M. nortoni nortoni was characterized by a series of alkyl spiroacetals andR. persuasoria contained 3-hydroxy-3-methylbutan-2-one. The same spiroacetals have previously been isolated from the mandibular glands of other Hymenoptera and have been directly associated with aggregation behavior in some species. The chemical and behavioral aspects of the two species are discussed.

Odor mimetism? : Key substances inOphrys lutea-Andrena pollination relationship (Orchidaceae: Andrenidae)

The hypothesis of chemical mimesis in the relationship betweenOphrys orchids and their pollinators was tested experimentally using preparations ofOphrys lutea var.lutea odor and the males of the solitary beeAndrena fuscipes, a species constellation that does not coexist under natural conditions. Correspondence in odor production was shown to occur. Identification of the compounds in the cephalic secretion ofA. fuscipes, males and females, and the flower labella extracts, was performed by gas chromatography and mass spectrometry. Geraniol, nerol, citral,E,E-farnesol and 6-methyl-5-hepten-2-one were present in the extracts of both the orchid and one or both sexes of the bee. Extracts, TLC fractions of extracts, blends, and separate compounds were tested in the field in the mating flight areas ofA. fuscipes males. Extracts and blends containingE,E-farnesol, geraniol, and geranial showed the highest attractivity to the male bees. These compounds seem to be responsible for the release of the odor-guided mating behavior at theO. lutea labellum and can be regarded as general attractants for many species ofAndrena.

Asymmetric synthesis of naturally occurring spiroketals

Spiroketals are widely found as substructures of many naturally occurring compounds from diverse sources including plants, animals as well as microbes. Naturally occurring spiroketals are biologically active and most of them are chiral molecules. This article aims at reviewing the asymmetric synthesis of biologically active spiroketals for last 10 years (1998-2007).

Chemical communication by behaviour-guiding olfactory signals

Chemical Ecology is a new interdisciplinary research area with close collaborations between chemists and biologists of different descriptions. It has developed during the last 40 years because of an interest in the structure, function and evolution of chemical signalling among organisms and also because of the hope to be able to use the ubiquitous phenomenon to control organisms, like pest insects. This feature article highlights the growth of the discipline and the progress made, through examples from the author's own work on chemical communication in insects and flowering plants. The research deals with olfactory signals, i.e. volatile chemical compounds perceived by the sense of smell. Analytical techniques and methods are an important part of the work.

Mating behavior and chemical communication in the order Hymenoptera

Insects of the order Hymenoptera are biologically and economically important members of natural and agro ecosystems and exhibit diverse biologies, mating systems, and sex pheromones. We review what is known of their sex pheromone chemistry and function, paying particular emphasis to the Hymenoptera Aculeata (primarily ants, bees, and sphecid and vespid wasps), and provide a framework for the functional classification of their sex pheromones. Sex pheromones often comprise multicomponent blends derived from numerous exocrine tissues, including the cuticle. However, very few sex pheromones have been definitively characterized using bioassays, in part because of the behavioral sophistication of many Aculeata. The relative importance of species isolation versus sexual selection in shaping sex pheromone evolution is still unclear. Many species appear to discriminate among mates at the level of individual or kin/colony, and they use antiaphrodisiacs. Some orchids use hymenopteran sex pheromones to dupe males into performing pseudocopulation, with extreme species specificity.

Chiral Synthesis via Organoboranes. 47. Efficient Synthesis of Unsymmetrical Ketones and Enantiomerically Pure Spiroketals Using (+/-)-Isopinocampheyldichloroborane

Readily prepared and stable (+/-)-isopinocampheyldichloroborane [(+/-)-IpcBCl(2)] was conveniently used for the stepwise hydroboration of two different alkenes using the in situ reduction-hydroboration protocol to give mixed trialkylboranes, IpcBR(1)R(2). Convenient elimination of alpha-pinene from these trialkylboranes by treatment with an aldehyde, RCHO, provided the borinate ester, R(1)R(2)BOCH(2)R. This intermediate was readily converted into the unsymmetrical ketones, R(1)COR(2), in high yields and purity, by an established method. This methodology was successfully applied to the synthesis of enantiomerically pure spiroketals using optically pure TBS ether protected homoallylic alcohols as the alkenes for stepwise hydroboration.

Identification and synthesis of new bicyclic acetals from the mountain pine beetle, Dendroctonus ponderosae Hopkins (Col.: Scol.)

Head-space volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae, were analyzed by coupled GC-MS and chiral gas chromatography. 5-Ethyl-7-methyl-6,8-dioxabicyclo[3.2.1]octane (6) was found as a new naturally occurring isomer of brevicomin (1). In addition, several stereoisomers of 7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1]octan-2-ol (11) and 1-(5-methyl-6,8-dioxabicyclo[3.2.1]octyl)ethanol (12) could be identified. Relative and absolute configurations of the compounds were determined by unambiguous syntheses, which are described.