Species-Specific Volatile Substances in the Venom Sac of Hover Wasps

Analyses of the volatile compounds in the venom sacs of seven species of stenogastrine wasps, belonging to three different genera, have revealed a mixture of linear alkanes and alkenes, with a chain length ranging from C₁₁ to C₁₇ in all the species. Among conspecifics, the composition of the mixture was consistent, while clear differences have been found between different species. Venom glands of some species also contained oxygenated compounds and, in one species, some pyrazines. Most of these compounds were found to be species-specific but were not always found in every individual of a species. In the genus Parischnogaster, P jacobsoni and P. mellyi showed the presence of some spiroacetals that were not found in P. alternata and P. striatula. The possible functions of the venom sac volatiles in the biology of the Stenogastrinae are discussed.     

Appended Aromatic Moieties in Flexible Bis-3-chloropiperidines Confer Tropism against Pancreatic Cancer Cells

Nitrogen mustards (NMs) are an old but still largely diffused class of anticancer drugs. However, spreading mechanisms of resistance undermine their efficacy and therapeutic applicability. To expand their antitumour value, we developed bis-3-chloropiperidines (B-CePs), a new class of mustard-based alkylating agent, and we recently reported the striking selectivity for BxPC-3 pancreatic tumour cells of B-CePs bearing aromatic moieties embedded in the linker. In this study, we demonstrate that such tropism is shared by bis-3-chloropiperidines bearing appended aromatic groups in flexible linkers, whereas esters substituted by aliphatic groups or by efficient DNA-interacting groups are potent but nonselective cytotoxic agents. Besides, we describe how the critical balance between water stability and DNA reactivity can affect the properties of bis-3-chloropiperidines. Together, these findings support the exploitation of B-CePs as potential antitumour clinical candidates.     

Identification of a Sex Pheromone Produced by Sternal Glands in Females of the Caddisfly <Emphasis Type="Italic">Molanna angustata</Emphasis> Curtis

In the caddisfly Molanna angustata, females produce a sex pheromone in glands with openings on the fifth sternite. Gas chromatographic analyses of pheromone gland extracts with electroantennographic detection revealed four major compounds that stimulated male antennae. These compounds were identified by means of gas chromatography–mass spectrometry and enantioselective gas chromatography as heptan-2-one, (S)-heptan-2-ol, nonan-2-one, and (S)-nonan-2-ol in the approximate ratio of 1:1:4:10, respectively. Field tests showed that the mixture of the two alcohols was attractive to males whereas addition of the corresponding ketones reduced trap catches. The sex pheromone of M. angustata, a species in the family Molannidae within the suborder Integripalpia, is similar to the pheromones or pheromone-like compounds previously reported from six other trichopteran families, including members of the basal suborder Annulipalpia. This suggests that minimal evolutionary change of the pheromone chemistry has taken place within the leptoceroid branch of integripalpian Trichoptera compared to the ancestral character state.     

Identification of Sex Pheromone Components of the Hessian Fly, <Emphasis Type="Italic">Mayetiola destructor</Emphasis>

Coupled gas chromatographic (GC)–electroantennographic detection (EAD) analyses of ovipositor extract of calling Hessian fly, Mayetiola destructor, females revealed that seven compounds elicited responses from male antennae. Four of the compounds—(2S)-tridec-2-yl acetate, (2S,10Z)-10-tridecen-2-yl acetate, (2S,10E)-10-tridecen-2-yl acetate, and (2S,10E)-10-tridecen-2-ol—were identified previously in female extracts. Two new EAD-active compounds, (2S,8Z,10E)-8,10-tridecadien-2-yl acetate and (2S,8E,10E)-8,10-tridecadien-2-yl acetate, were identified by GC–mass spectroscopy (MS) and the use of synthetic reference samples. In a Y-tube bioassay, a five-component blend (1 ng (2S)-tridec-2-yl acetate, 10 ng (2S,10E)-10-tridecen-2-yl acetate, 1 ng (2S,10E)-10-tridecen-2-ol, 1 ng (2S,8Z,10E)-8,10-tridecadien-2-yl acetate, and 1 ng (2S,8E,10E)-8,10-tridecadien-2-yl acetate) was as attractive to male Hessian flies as a similar amount of female extract (with respect to the main compound, (2S,10E)-10-tridecen-2-yl acetate). The five-component blend was more attractive to male flies than a three-component blend lacking the two dienes. Furthermore, the five-component blend was more attractive than a blend with the same compounds but that contained one tenth the concentration of (2S,8E,10E)-8,10-tridecadien-2-yl acetate (more accurately mimicking the ratios found in female extract). This suggests that the ratios emitted by females might deviate from those in gland extracts. In a field-trapping experiment, the five-component blend applied to polyethylene cap dispensers in a 100:10 μg ratio between the main component and each of the other blend components attracted a significant number of male Hessian flies. Also, a small-plot field test demonstrated the attractiveness of the five-component blend to male Hessian flies and suggests that this pheromone blend may be useful for monitoring and predicting Hessian fly outbreaks in agricultural systems.     

Major Sex Pheromone Component of Female Herald Moth Scoliopteryx libatrix is the Novel Branched Alkene (6Z,13)-Methylheneicosene

The major component of the female-produced sex pheromone of Scoliopteryx libatrix has been characterized by chemical analysis, synthesis, electrophysiological studies and field tests as (6Z,13)-methylheneicosene, probably the 13S-isomer. This is the first example of a branched chain alkene as a sex pheromone in the Noctuidae and is markedly different from the pheromones of other members of the family. The systematic position of S. libatrix, belonging to a monotypic genus of a one-member subfamily within the Noctuidae, may reflect the unusual structure of the sex pheromone.     

Modification of carbon nanostructures by high energy ball-milling under argon and hydrogen atmosphere

High energy ball-milling of graphite leads to nanocrystalline structures of carbon. The structures are characterised by small crystalline particles embedded in an amorphous matrix causing a high specific surface area. To investigate and quantify these nanostructures X-ray powder diffraction, high resolution transmission electron microscopy and specific surface area measurements were used. By changing the atmosphere in milling vials from argon to hydrogen the generation of the graphitic nanostructures can be decelerated. Thereby, it is possible to modify the structures in a definite way and to receive higher specific surface areas for longer milling times. Furthermore, during milling under hydrogen atmosphere the broken carbon bonds are saturated by hydrogen. In this way, it is possible to stabilise the produced nanostructures and to prevent agglomeration.     

Identification of sex pheromone composition of click beetle Agriotes brevis candeze

Geranyl butyrate (GB) and (E,E)-farnesyl butyrate (FB) were identified in the pheromone gland extract of females of the click beetle, Agriotes brevis (Candeze) (Coleoptera: Elateridae) as the major sex pheromone components. Polyethylene vial dispensers containing 20–200 mg of a 1:1 mixture caught high numbers of beetles. Captures did not decrease even after 73 days of field exposure of dispensers. At sites where both Agriotes sputator L. and A. brevis were present, the above baits were selectively catching only A. brevis, despite the fact that GB is also the main pheromone component of A. sputator, suggesting that FB has a role in reproductive isolation. In the early part of the season, traps into which the insects could both crawl and fly captured more A. brevis than designs where the insects could only fly in. Trap design was not important later in the season. This indicates the need for future development of a trap suitable for use throughout the whole season.     

Trail pheromone of ponerine ant Gnamptogenys striatula: 4-methylgeranyl esters from Dufour's gland

Dufour's gland is the origin of the trail pheromone of Gnamptogenys striatula. Chemical analysis of the glandular extracts revealed a series of new natural products, especially esters of (2E)-3,4,7-trimethyl-2,6-octadien-1-ol (4-methylgeraniol), and (2E)-3,4,7-trimethyl-2,6-nonadien-1-ol (a bishomogeraniol isomer) with medium-chain fatty acids. Bioassays with synthetic racemates of the esters revealed that the 4-methylgeranyl esters are highly active as trail pheromones, while the bishomogeranyl esters are either marginally active or not active at all. Assays with the individual 4-methylgeranyl esters showed each of them to be inferior to the glandular secretion in eliciting trail following. However, the mixture of racemic 4-methylgeranyl octanoate and the corresponding decanoate and dodecanoate, the main Dufour's volatile constituents, is as active as the natural secretion at similar concentration. We conclude that the trail pheromone constitutes a mixture of at least the 4-methylgeranyl esters identified in the gland. Since G. striatula generally preys on small arthropods rather than monopolizing large resources, we assume that trails are rarely used during foraging, but more often during nest migration. Production of new societies in this species is generally performed by budding, a period of considerable predation risk. Utilizing trails for efficient displacement in this context is, therefore, highly adaptive. This behavioral repertoire may also provide the ants with additional means of food resource exploitation.