Tetranorsesquiterpenoids as Attractants of Yucca Moths to Yucca Flowers

Journal of Chemical Ecology - The obligate pollination mutualism between Yucca and yucca moths is a classical example of coevolution. Oviposition and active pollination by female yucca moths occur...     

Defensive Compounds and Male-Produced Sex Pheromone of the Stink Bug, Agroecus griseus

Agroecus griseus is a serious corn pest in Brazil. Contents of the dorsal abdominal glands (DAGs) in nymphs, and the metathoracic gland (MTG) in adults of this species were characterized and quantified. Compounds found were similar to those of other Pentatomidae species and included aliphatic hydrocarbons, aldehydes, oxo-alkenals, and esters. However, two compounds were found in the MTG that have not been described previously for this family. Mass spectrometry, infrared spectroscopy, and gas chromatographic analysis using coinjection with authentic standards confirmed the identities of the compounds as enantiopure (S)-2-methylbutyl acetate and 3-methyl-2-butenyl acetate. The five nymphal instars showed significantly different ratios of components, mainly between those of the first and later instars. No significant differences were detected in MTG contents between sexes. Gas chromatography (GC) analysis of aeration extracts of males and females showed the presence of a compound released exclusively by males. Gas chromatography – electroantennographic detection (GC-EAD) assays indicated that the male-specific compound is bioactive in females, suggesting the presence of an attractant pheromone. The mass spectrum and infrared data for this compound matched with methyl 2,6,10-trimethyltridecanoate, a sex pheromone component previously detected in the stink bugs, Euschistus heros and E. obscurus. The synthetic standard coeluted with the natural pheromone on two different GC stationary phases, confirming the proposed structure. Y-tube olfactometer assays showed that the synthetic standard was strongly attractive to females, and GC-EAD tests produced responses with antennae from females similar to those of the natural pheromone.     

Biosynthesis of scarab beetle pheromones

Chemical communication in scarab beetles (Coleoptera: Scarabaeidae) is achieved with a wide variety of pheromones, but one typical structure is the gamma-lactone having a long unsaturated hydrocarbon chain. Several species utilize (R, Z)-5-(-)-(oct-1-enyl)-oxacyclopentan-2-one (buibuilactone), (R, Z)-5-(-)-(dec-1-enyl)-oxacyclopentan-2-one and (S, Z)-5-(+)-(dec-1-enyl)-oxacyclopentan-2-one [(R)-japonilure and (S)-japonilure]. Using deuterated precursors, we have demonstrated that these compounds are biosynthesized from fatty acids. (9, 10-d4)-Palmitic acid, (9,10-d4)-stearic acid, (9,10-d2)-palmitoleic acid, (9,10-d2)-oleic acid, (9,10-d2)-8-hydroxypalmitoleic acid and (9,10-d2)-8-hydroxyoleic acid were readily incorporated by female Anomala cuprea into the pheromone molecules, while (Z)-(5, 6-d2)-5-dodecenoic acid and (Z)-(5,6-d2)-5-tetradecenoic acid were not. Therefore, the reaction pathway starts from saturated fatty acids, involves their desaturation, followed by 8-hydroxylation, chain shortening and cyclization. The products obtained from racemic (9,10-d2)-8-hydroxypalmitoleic acid and (9,10-d2)-8-hydroxyoleic acid were also racemic, implying that the steps following hydroxylation were not stereospecific. Perdeuterated palmitic acid was applied to disclose the mechanism of the unique hydroxylation reaction. Retention of all deuterium atoms implied that this reaction was a direct process mediated by a specific fatty acid hydroxylase, and preceding desaturation or epoxidation was not involved.     

Preparation and transplantation of photoreceptor sheets

PURPOSE: Photoreceptor (PR) transplantation may be a treatment for blindness secondary to PR degeneration. We studied different technical aspects of PR-sheet preparation. METHODS: Geographic variation in the thickness of the cat PR layer (from the outer segments to the outer plexiform layer) and inner retina (width of the remainder of the retina) was studied. PR sheets (cat and human) were prepared through gelatin embedding and subsequent vibratoming or excimer laser ablation. Cat PR sheets were evaluated after transplantation. RESULTS: The thickness of the cat PR layer and inner retina varied in different regions. The superior central retina, including the area centralis, was thickest (PR layer: 115-123 microm, entire retina: 225-230 microm, in fixed tissue). The peripheral retina was approximately 40% thinner than the center. Fresh retina was approximately 7.9% thicker than the fixed retina. Both vibratomy and excimer laser ablation removed the inner retina, leaving a PR-layer sheet with good morphology. To produce good quality PR sheets with vibratomy, use of different gelatin concentrations (2% to 35%) at various stages of sheet preparation was crucial. To produce PR sheets of uniform thickness with excimer laser ablation, control of fluid on the retinal surface was critical. Twenty-four hours after PR transplantation surgery, donor PR cells were well oriented and in close contact with host retinal pigment epithelial cells. Gelatin supporting the transplant dissolved as early as 100 min after surgery. CONCLUSIONS: We confirmed and expanded the work of previous investigators and showed that cat and human PR sheets can be manufactured using vibratomy or excimer laser ablation. This preparation provides a well oriented and organized PR cell layer after transplantation.     

Sex Pheromone of the Bud Borer <Emphasis Type="Italic">Epinotia aporema</Emphasis>: Chemical Identification and Male Behavioral Response

Epinotia aporema (Walsingham) is a Neotropical pest of legumes in southern South America. Its importance has increased during the last decade owing to the significant growth of soybean production in the region. Monitoring of E. aporema is difficult due to the cryptic behavior of the larvae, and hence, chemical control is carried out preventively. We analyzed the female-produced sex pheromone so as to develop monitoring traps and explore pheromone-based control methods. We analyzed pheromone gland extracts by combined chromatographic, spectrometric, and electrophysiological methods. Based on the comparison of retention indices, mass spectra, and electroantennogram (EAD) activity of the insect-produced compounds with those of synthetic standards, we identified two EAD-active compounds, (Z,Z)-7,9-dodecadienol and (Z,Z)-7,9-dodecadienyl acetate (15:1 ratio), as sex pheromone components of E. aporema. We also studied the behavior of males in wind tunnel tests using virgin females and different combinations of synthetic standards (15:1, 1:1, and 1:0 alcohol/acetate) as stimuli. A significantly greater percentage of males reached the chemical source with the 15:1 synthetic mixture than with any of the other treatments, indicating that these two compounds are pheromone components. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Volatile Organic Compounds of Conspecific-Damaged Eucalyptus benthamii Influence Responses of Mated Females of Thaumastocoris peregrinus

Plants respond to herbivory by synthesizing and releasing novel blends of volatile organic compounds (VOCs). Natural enemies are attracted to these VOCs, but little is known about the effects of these chemicals on the herbivores themselves. We studied the effect of Thaumastocoris peregrinus herbivory on VOCs released by Eucalyptus benthamii plants and the responses of this herbivore to the VOCs. In total, 12 compounds released by E. benthamii were identified. Five compounds (β-pinene, linalool, 9-epi-(E)-caryophyllene, viridiflorol, and one unidentified compound) emitted after herbivore and mechanical damage were not detected in collections from undamaged plants. The three most abundant VOCs, α-pinene, aromadendrene, and globulol, were released in greater quantities from herbivore-damaged plants compared to plants with mechanical damage, which, in turn, released greater amounts than undamaged (control) plants. The VOCs emitted after herbivore damage did not differ during the photophase and scotophase in either quantity or quality. In an olfactometer, mated female T. peregrinus showed a preference for undamaged plants over herbivore-damaged plants, and also for hexane over α-pinene at an amount equivalent to that released by a herbivore-damaged plant. In the olfactometer, virgin females did not exhibit any preference between conspecific-damaged or undamaged plants.     

Biosynthesis and Site of Production of Sex Pheromone Components of the Cerambycid Beetle, Hedypathes betulinus

We determined the site of pheromone production tissues and a partial route for the biosynthesis of the sex pheromone in Hedypathes betulinus (Coleoptera: Cerambycidae: Lamiinae), Brazil’s main green maté pest. Pheromone was found predominantly in the prothorax of males, suggesting that this is the region of production of pheromones in this insect. Scanning electron microscopy revealed small pores that may be associated with pheromone release in males; these pores also were observed in females. A deuterium-labeled putative precursor (geranyl acetone-D₅) of the sex pheromone of H. betulinus was synthesized. When applied to the prothorax of males, label from the precursor was incorporated into the pheromone components, confirming that pheromone production occurs in the prothorax and that the pheromone components are biosynthesized from geranyl acetone.     

Identification of male-specific chiral compound from the sugarcane weevil Sphenophorus levis

Comparative gas chromatographic analyses of airborne volatiles produced by males and females of the sugarcane weevil Sphenophorus levis, showed one male-specific compound. Gas chromatography–mass spectrometry data indicated an aliphatic alcohol that was identified as 2-methyl-4-octanol. Both optical isomers were synthesized in five steps by employing commercially available (R)- and (S) -2,2-dimethyl-1,3-dioxolane-4-methanol as starting material. Enantiomeric resolution by gas chromatography with a chiral column demonstrated that the natural alcohol possessed the S configuration. Preliminary indoor observations suggested that the alcohol elicited aggregation behavior among adults. The same compound has been previously described as an aggregation pheromone in several other curculionid species.     

A Simple and Innovative Route to Prepare a Novel Carbon Nanotube/Prussian Blue Electrode and its Utilization as a Highly Sensitive H2O2 Amperometric Sensor

The utilization of iron‐based species (mainly metallic iron, hematite and magnetite) encapsulated into multi‐walled carbon nanotubes (CNTs) as reactants in an electrochemical synthesis is reported for the first time in this work. Prussian blue (PB) is electrosynthesized in a heterogeneous reaction between ferricyanide ions in aqueous solution and the iron‐species encapsulated into CNTs, resulting in novel CNT/PB paste electrodes. This innovative preparation route produces an intimate contact between the PB and the CNTs, which improves the stability and redox properties of PB. The PB formation and the chemical interaction between the PB and the CNTs are confirmed by Raman spectroscopy. The electrode is employed as a hydrogen peroxide amperometric sensor, resulting in a very low limit of detection (1.94 × 10^?8 mol L^?1) and very high sensitivity (15.3 A cm^?2 M ^?1).     

Polyphosphate based electrochemical capacitors

Environmentally friendly electrochemical capacitors (ECs) were assembled using hybrid materials formed by a polyphosphate gel matrix in which carbon-based materials were inserted and polyaniline were formed in a single-step synthesis. The hybrid materials were deposited on FTO glasses and symmetric ECs were assembled using a cellulose membrane soaked with an aqueous NaH₂PO₄ solution as a separator. The capacitance values were calculated from impedance spectroscopy and galvanostatic charge/discharge measurements. The devices showed capacitances ranging from 4.0 to 27.0 F cm^?3, which are comparable to some commercial devices. Better results were achieved in samples with polyaniline, which were ascribed to the pseudocapacitance impaired to the samples by the conducting polymer.