Defining a synthetic pheromone blend attractive to male Heliothis subflexa under wind tunnel conditions

Heliothis subflexa males were flown in a wind tunnel to a variety of combinations of synthetic pheromone components admixed on a filter paper disk. Blends containing (Z)-11-hexadecenal (Z11–16:Ald, 1000 ng), (Z)-9-hexadecenal (Z9–16:Ald, 500 ng) and (Z)-11-hexadecenol (Z11–16:OH, 10–500 ng) elicited upwind flight and source contact in 52–69% of males. All these compounds have previously been isolated and identified from female H. subflexa gland extracts and volatile pheromone emissions. Males were not attracted by blends in which Z9–16:Ald was omitted (0% source contact). Similarly, blends lacking Z11–16:OH were unattractive to male H. subflexa (3% or less source contact). Males were extremely sensitive to the presence of Z11–16:OH; however, responding in high numbers (57–69% source contact) to blends containing a dosage of 1% (10 ng) or greater Z11–16:OH. Males were unresponsive to blends in which Z9–16:Ald was replaced with a variety of dosages of (Z)-9-tetradecenal, a secondary component of a closely-related congeneric species, Heliothis virescens. Another compound present in the blend emitted by conspecific females, (Z)-11-hexadecenyl acetate (Z11–16:Ac), did not inhibit H. subflexa males (69% source contact) when added to the three-component mixture (1:0.5:0.1) at a ratio of 0.1 (100 ng) with respect to Z11–16:Ald. These results indicate that Z9–16:Ald and Z11–16:OH are required in addition to Z11–16:Ald to elicit significant levels of upwind flight in H. subflexa males. The effects of Z11–16:Ac are more subtle, but at the dosage tested in these experiments, this compound does not have an antagonistic effect on upwind flight and source location by H. subflexa males.     

Changed isoflavone Levels in Red Clover (<Emphasis Type="Italic">Trifolium pratense</Emphasis> L.) Leaves with Disturbed Root Nodulation in Response to Waterlogging

The effect of disturbed root nodulation on the quantitative and qualitative composition of the main isoflavonoid glucoside–malonates, glucosides, and aglycones in the leaves of Trifolium pratense L. grown under waterlogging conditions was investigated. Isoflavonoids are involved in the regulation of root nodule activity and the establishment of the mycorrhizal association. Isoflavonoid determination was performed using reversed-phase liquid chromatography coupled to mass spectrometric and UV absorbance detection. In response to waterlogging, the concentrations of biochanin A and biochanin A–7-O-glucoside–malonate, biochanin A–7-O-glucoside, and genistein–7-O-glucoside in the leaves increased two- to threefold after a lag period of 3 wk because of disturbed root nodulation. The other isoflavones detected—formononetin, formononetin–7-O-glucoside–malonate, and formononetin–7-O-glucoside—did not show any significant changes related to waterlogging. After restoring normal soil water conditions, the concentrations of biochanin A and its glucoside and glucoside–malonate rapidly returned to the initial values, whereas the concentration of genistein–7-O-glucoside remained high.     

Inhibition of copper corrosion by several Schiff bases in aerated halide solutions

The inhibitive action of three Schiff bases, N,N -o-phenylen-bis(3-methoxysalicylidenimine) (V–o-Ph–V), N,N -p-phenylen-bis (3-methoxysalicylidenimine) (V–p-Ph–V) and N-[(2-hydroxy-3-methoxyphenyl)methylene]-histidine (V-His), on copper corrosion in aerated 0.5 mol dm^–3 NaCl and NaBr solutions was investigated using EIS and steady-state polarization techniques. The inhibitor effectiveness depended strongly on the geometric structure of the Schiff bases. Among the three kinds of Schiff base used, the inhibition efficiency of V–o-Ph–V on copper corrosion was the highest, V–p-Ph–V the next and V-His the lowest. The Schiff bases inhibited the cathodic current more significantly than the anodic current. The different influences of V–o-Ph–V or V–p-Ph–V on the anodic and cathodic reactions led to the appearance of a low frequency capacitive loop in the impedance spectra. The inhibition action of the Schiff bases was due to their adsorption on the copper surface followed by complexation with Cu(I) or Cu(II) ions, forming a blocking barrier to copper corrosion.     

Living Anionic Polymerization of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>–Dimethylacrylamide and Copolymerization with Methyl Methacrylate in the presence of Bulky Aluminum Phenoxide

Summary Anionic polymerization of N,N–dimethylacrylamide (DMAAm) was examined in toluene with tert–butyllithium (t–BuLi)/bis(2,6–di–tert–butylphenoxy)ethylaluminum [EtA1(ODBP)₂]. In the presence of excess amounts of the aluminum compound over t–BuLi, the polymerization proceeded in a living manner. Sequential block copolymerization of DMAAm and methyl methacrylate (MMA) with the same initiator underwent smoothly in both directions, that is, polymerization of MMA by poly(DMAAm) living anions and vice versa. Moreover, the copolymerization of an equimolar mixture of DMAAm and MMA proceeded in a monomer–selective manner to give a block–like copolymer; DMAAm was polymerized first followed by MMA polymerization through selective activation of DMAAm by the coordination of EtA1(ODBP)₂.     

Subtleties in Perception and Discrimination by Cabbage Looper Moths, Trichoplusia ni, of the two 14-carbon Acetate Sex Pheromone Components

Three compounds that are emitted by virgin female cabbage looper moths, Trichoplusia ni, (Z)-7-dodecenyl acetate (Z7–12:Ac), (Z)-7-tetradecenyl acetate (Z7–14:Ac), and (Z)-9-tetradecenyl acetate (Z9–14:Ac), are detected by antennal olfactory receptor neurons specialized to detect sex pheromone components. The principal evidence signifying that either or both of Z7–14:Ac and Z9–14:Ac have an effect on male behavior comes from an observed reduction in the numbers of males trapped by Z7–12:Ac paired with a six-component mixture. The evidence conforms to a hypothesis that either or both of these compounds are the basis for discrimination between the two mixtures. However, scant evidence for this hypothesis was obtained in paired-source laboratory wind-tunnel assays, even at airborne concentrations of Z7–14:Ac and Z9–14:Ac that ranged up to 1000× that emitted by a female. Furthermore, there was little evidence from single-source laboratory or field trap assays confirming that Z7–14:Ac and Z9–14:Ac at or above natural stimulus strengths modify the moth's perception of Z7–12:Ac. The data suggest that discrimination of small mixture differences may not be resolvable within the confines of a wind tunnel.     

Identification of a Sex Pheromone Component of the Raspberry Budmoth, Heterocrossa rubophaga

The female-produced sex pheromone of the New Zealand raspberry budmoth, Heterocrossa rubophaga, was investigated. Gas chromatographic–mass spectrometric analyses revealed the ketone, (Z)-12–nonadecen9–one (Z12–19–9–one). This compound had previously been found in extracts of the sex pheromone gland of the only other carposine moth for which a sex pheromone has been identified, Carposina niponensis, although its effect on the behavior of C. niponensis males had not been established. Field trapping trials in berry fruit gardens showed this compound to elicit high catches of male H. rubophaga, with the catch appearing to plateau (and perhaps decrease) above a dosage of 300 g on a red rubber septum. In an analysis of an extract of female H. rubophaga sex pheromone glands, there was a suggestion that the homologous (Z)-7–eicosen-11–one, the known sex pheromone component of C. niponensis, was also present. However this could not be established unequivocally and, in a field trial, addition of a small amount of this compound to Z12–19–9–one resulted in no significant increase in trap catch relative to traps baited with Z12–19–9–one alone.     

Thermodynamic Properties of Aqueous Solutions of Alkanes under Supercritical Conditions

P–V–T–X relationships for the water–methane, water–n-pentane, water–n-hexane, water–n-heptane, and water–n-octane systems are derived by piezometry at a constant volume in the vicinity of the critical point of water (647.096 K) and up to 673.15 K at pressures up to 40 MPa and alkane mole fractions of 0–1.0. Conditions are determined under which real mixtures behave as an ideal gas or have a constant compressibility factor. It is demonstrated that the concentration dependence of the partial molar volumes of alkanes in the range of small concentrations is asymptotic if the isothermal isobar of the solvent is critical. The molecular parameters of the equation of state that is based on perturbed-hard-chain theory are determined and used in the calculation of thermodynamic parameters for this class of solutions.     

Identification of Female Sex Pheromone of the Rice Leaf Bug, Trigonotylus caelestialium

The female sex pheromone of the rice leaf bug, Trigonotylus caelestialium, was analyzed by GC-EAD and GC-MS. Ten EAD active compounds—n-hexyl n-hexanoate, (E)-2-hexenyl n-hexanoate, n-hexyl (E)-2-hexenoate, n-octyl n-butyrate, n-octyl n-hexanoate, (E)-2-octenyl n-hexanoate, n-pentyl n-hexanoate, n-hexyl n-butyrate, (E)-2-hexenyl n-butyrate, and n-hexyl (E)-2-butenoate—were detected in the ratio of 1000:414–491:trace–5:5–11:55–71:50–63:trace–3:225:90:32 from female body extracts, and in the ratio of 1000:271–342:10–43:1–3:58–78:14–19:trace:178:36:26 from male body extracts. Field trapping tests with these synthetic compounds indicated that n-hexyl n-hexanoate, (E)-2-hexenyl n-hexanoate, and n-octyl n-butyrate are pheromone components, and mixtures in ratios of 1000:400–500:10–100 were more attractive to males. Doses ranging from 4.29 g to 14.3 g of the three-component mixture in the ratio of 1000:400:30 loaded into glass capillary tubes were most attractive to males.     

(Z)-11-Eicosenyl acetate,an aggregation pheromone inDrosophila malerkotliana

(Z)-11-Eicosenyl acetate (Z11–20:Ac) was identified as the aggregation pheromone inDrosophila malerkotliana. The pheromone (200–300 ng/fly) was isolated from hexane extracts of the ejaculatory bulb of sexually mature male flies. Males released very little, if any,Z11–20:Ac to the food at any time. During mating there was a transfer of ca. 100 ng ofZ11–20:Ac to the female's reproductive tract. The mated female fly transferred theZ11–20:Ac to the surrounding surfaces in just a few hours after mating. In bioassay in a wind-tunnel olfactometer,Z11–20:Ac was not attractive alone, but was synergistic with fermenting food or with acetone. AlthoughD. malerkotliana has no (Z)-11-octadecenyl acetate (Z11–18:Ac), it was as attracted toZ11–18:Ac as to an equal quantity ofZ11–20:Ac.D. melanogaster andD. simulans, however, responded to theZ11–18: Ac that they produced and did not respond toZ11–20:Ac.     

Sex pheromone of tomato fruit borer, Neoleucinodes elegantalis

Five candidate pheromone components were identified by analyzing pheromone gland extracts by gas chromatography (GC), coupled GC-electroantennographic detection (EAD), and coupled GC-mass spectrometry (MS): (E)-11-hexadecenol(E11–16 : OH), (Z)-11-hexadecenol (Z11–16 : OH),(E)-11-hexadecenal, (E)-11-hexadecenyl acetate, and (Z)-3,(Z)-6,(Z)-9-tricosatriene (Z3,Z6,Z9–23 : Hy). In electroantennogram (EAG) recordings, synthetic E11–16 : OH elicited stronger antennal responses at low doses than other candidate pheromone components. Field tests demonstrated that synthetic E11–16 : OH as a trap bait was effective in attracting males, whereas addition of Z11–16 : OH inhibited the males' response. Z3,Z6,Z9–23 : Hy strongly enhanced attractiveness of E11–16 : OH, but was not attractive by itself. A pheromone blend with synergistic behavioral activity of an alcohol (E11–16 : OH) and hydrocarbon (Z3,Z6,Z9–23 : Hy) component is most unusual in the Lepidoptera. The synthetic two-component pheromone is approximately 60 times more attractive than the female-produced blend and might facilitate the control of this pest.     

A comparative study of the effect of different drag-reducing polymers on electrochemical mass transfer

The effect of Polyox, Separan and CMC drag-reducing polymers on the rate of electrochemical mass transfer was studied using the cathodic reduction of K₃Fe(CN)₆ in neutral media at a rotating cylinder cathode. Reynolds number and polymer concentration were varied over the ranges 764–10470 and 10–200 ppm respectively. Under these conditions it was found that the three polymers reduce the rate of mass transfer by a maximum of 47%, 30%, and 17% for Polyox, Separan and CMC, respectively. Mass transfer data in the three polymer solutions was correlated by the following equations: for Polyox: (St)=0.051(Re)^–0.3 (Sc)^–0.644 (u/u ₀ ^–0.7 for Separan: (St)=0.065(Re)^–0.3 (Sc)^–0.644 (u/u ₀)^–0.7 for CMC: (St)= 0.075(Re)^–0.3 (Sc)^–0.644) (u/u ₀)^–0.5 List of symbols I limiting current density (A cm^–2) - Z number of electrons involved in the reaction - F Faraday's constant - K mass transfer coefficient (cm s^–1) - V linear velocity of the cylinder (cm s^–1) - D diffusion coefficient (cm²s^–1) - v kinematic viscosity (cm²s^–1) - d diameter of the cylinder (cm) - u, u ₀ viscosity of solutions with and without polymer respectively (P) - density (g cm^–3) - c concentration of Fe(CN) ₆ ^3– (mol cm^–3) - (St) Stantonnumber=K/V - (Sc) Schmidt number=v/D - (Re) Reynolds number=Vd/u     

Synthesis, characterization and catalytic properties of an N-heterocyclic carbene palladium-based complex

A palladium(II) complex, bis[1,3-bis-(2,4,6-trimethylbenzyl)benzimidazol-2-ylidene]palladium(II) chloride, Pd(NHC), bearing N-heterocyclic carbenes has been synthesized and characterized by elemental analysis, IR spectroscopy and ¹H and ¹³C NMR spectroscopy. Crystal structure details of Pd(NHC) are also presented. The palladium centre in the complex lies on a crystallographic inversion centre and occupies a square-planar environment, with both chloride and N-heterocyclic carbene ligands adopting a trans arrangement with Cl–Pd–Cl and C–Pd–C angles are precisely 180°. The palladium–carbene complex was tested as a catalyst in the Suzuki–Miyaura cross-coupling reaction.     

Olfactory Responses of Plutella xylostella Natural Enemies to Host Pheromone, Larval Frass, and Green Leaf Cabbage Volatiles

The parasitoids Trichogramma chilonis (Hymenoptera: Trichogrammatidae) and Cotesia plutellae (Hymenoptera: Braconidae), and the predator Chrysoperla carnea (Neuroptera: Chrysopidae), are potential biological control agents for the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae). We present studies on the interactions between these bioagents and various host-associated volatiles using a Y olfactometer. T. chilonis was attracted to a synthetic pheromone blend (Z11–16:Ald, Z11–16:Ac, and Z11–16:OH in a 1:1:0.01 ratio), to Z11–16:Ac alone, and to a 1:1 blend of Z11–16:Ac and Z11–16:Ald. C. plutellae responded to the blend and to Z11–16:Ac and Z11–16:Ald. Male and female C. carnea responded to the blend and to a 1:1 blend of the major components of the pheromone, although no response was elicited by single compounds. Among the four host larval frass volatiles tested (dipropyl disulfide, dimethyl disulfide, allyl isothiocyanate, and dimethyl trisulfide), only allyl isothiocyanate elicited significant responses in the parasitoids and predator, but C. plutellae and both sexes of C. carnea did respond to all four volatiles. Among the green leaf volatiles of cabbage (Brassica oleracea subsp. capitata), only Z3–6:Ac elicited significant responses from T. chilonis, C. plutellae, and C. carnea, but C. plutellae also responded to E2–6:Ald and Z3–6:OH. When these volatiles were blended with the pheromone, the responses were similar to those elicited by the pheromone alone, except for C. carnea males, which had an increased response. The effect of temperature on the response of the biological agents to a mixture of the pheromone blend and Z3–6:Ac was also studied. T. chilonis was attracted at temperatures of 25–35°C, while C. plutellae and C. carnea responded optimally at 30–35°C and 20–25°C, respectively. These results indicate that the sex pheromone and larval frass volatiles from the diamondback moth, as well as volatile compounds from cabbage, may be used by these natural enemies to locate their diamondback moth host.     

Comparative Study of Pheromone Production and Response in Swedish and Zimbabwean Populations of Turnip Moth, Agrotis segetum

Analysis of female sex pheromone gland extracts of the turnip moth (or common cutworm), Agrotis segetum, from Zimbabwe revealed three compounds previously identified as sex pheromone components in the Swedish population, namely (Z)-5-decenyl acetate (Z5–10:OAc), (Z)-7-dodecenyl acetate (Z7–12:OAc), and (Z)-9-tetradecenyl acetate (Z9–14:OAc). However, the proportions from the Zimbabwean population (1:0.25:0.03) differ from those in the Swedish population (1:5:2.5). In addition, gas chromatography–mass spectrometric (GC-MS) analysis of the Zimbabwean female gland extracts revealed a trace of (Z)-5-dodecenyl acetate (Z5–12:OAc). This compound has recently been identified as a fourth sex pheromone component for the Swedish population. Single-sensillum recordings from both Zimbabwean and Swedish populations showed the presence of two types of antennal receptors responding to either Z5–10:OAc or Z7–12:OAc. In Zimbabwean males the Z7–12:OAc receptor neuron appeared to be confined to the basal and medial thirds of the antennal branches, while in Swedish males it was distributed along the entire antennal branch. Dose–response curves of Z5–10:OAc or Z7–12:OAc specific receptor neurons from males of both populations showed similar response profiles, but the neurons of the Zimbabwean population showed higher maximal responses. In flight tunnel tests with Zimbabwean males, the three-component Zimbabwean blend of Z5–10:OAc, Z7–12:OAc and Z9–14:OAc elicited significantly greater responses than the Swedish blend, but not significantly greater than pheromone glands from calling Zimbabwean females. (Z)-5-decenol (Z5–10:OH), a constituent of gland extracts, exerted an antagonistic effect in the flight tunnel. In field tests conducted in Sweden, local males were preferentially attracted to local females, while in Zimbabwe preferential attraction to local females was less pronounced. Local response to the Swedish and Zimbabwean synthetic four-component blends mirrored the responses to the local females. Zimbabwean males are much more strongly attracted to Z5–10:OAc alone than are Swedish males and the high concentrations of Z7–12:OAc and/or Z9–14:OAc present in the Swedish blend reduced attraction of Zimbabwean males. This reduced attraction appears to be counteracted by the trace amounts of Z5–12:OAc found in the Swedish four-component blend. Addition of Z5–12:OAc to the three-component Zimbabwean blend did not, however, significantly increase the trap catches of Zimbabwean males.     

A reaction model for the electrochemical production of p-anisidine

The work examines the possibility of a simple reaction model describing a complex organic electrosynthesis, such as the formation of p-anisidine. The experimental results obey the linear relationships of the model and in consequence the kinetic constants obtained in this way define reaction behaviour. The paper demonstrates how such a model can play a useful role in the design of pilot plant experimentation. Results from a parallel plate cell fit prediction from the model.Nomenclature [X] Concentration of species X (kmol m^–3) - b Slope of Tafel plot (mV^–1) - E Electrode potential (mV) - F Faraday (C g-equiv^–1) - F Faraday based on k-equiv = 10³F (C k-equiv^–1) - i _A Partial current density for the primary reaction (A m^–2) - i _B Partial current density for the consecutive secondary reaction (A m^–2) - i _H Partial current density for the parallel secondary reaction (A m^–2) - i Total current density=i _A+i _B+i _H (A m^–2) - k Reaction rate constant (A m^–2 per kmolm^–3) - k _H Rate constant for the parallel secondary electrode reaction (A m^–2) - k _I Individual mass transfer coefficient (m s^–1) - N Flux (kmol m^–2 s^–1) - r Reaction rate (kmol m^–2 s^–1) Sufixes A Appertaining to primary electrode reaction or species A - B Appertaining to consecutive secondary electrode reaction or species B - b In the bulk of the electrolyte - H Parallel secondary electrode reaction - s Near the electrode surface     

Enantiomeric composition of ipsdienol: A chemotaxonomic character for north American populations ofIps spp. in thepini subgeneric group (coleoptera: Scolytidae)

Thirty-five populations ofIps pini (Say) and one population each ofIps avulsus (Eichhoff) andIps bonanseai (Hopkins) were analyzed for the enantiomeric composition of ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol). Populations ofI. pini occur as at least two distinct regional pheromone variants: New York type [32%-(–) to 56%-(–)-ipsdienol] and California type [94%-(–) to 98%-(–)-ipsdienol]. A third phenotype may occur in southeastern British Columbia, Idaho, and Montana [91%-(–) to 95%-(–)], possibly indicating a zone of hybridization. Populations of the New York type occur in southwestern British Columbia, Alberta, Saskatchewan, Minnesota, and Wisconsin suggesting a continuum through the Canadian provinces and Lake States. The presence of the New York type in western Canada is likely linked to the Quaternary history of the transcontinentally distributed host,Pinus banksiana Lamb. MaleI. avulsus [25%-(–)] and maleI. bonanseai [–29%-(–)] both produce ipsdienol, but not ipsenol. Production of ipsdienol by maleI. pini was evaluated in six differentPinus spp. hosts. Following transfer of maleI. pini to hosts other than the host of origin, the percentage of the (–)-enantiomer of ipsdienol declined when compared to production in the host of origin.     

The effect of the type of electric current on the cathodic corrosion of aluminium

A comparative experimental study on the cathodic corrosion of aluminium in 0.52 M sodium chloride distilled water solutions is carried out. The electrolysis is conducted using a single half-cycle rectified, direct or industrial frequency current. Characteristic relationships concerning the cathodic corrosion are noted. Attention is drawn to the higher rates of cathodic corrosion observed on electrolysis with single half-cycle rectified current which is combined with lower energy costs.Nomenclature w _k1 cathodic corrosion rate for direct current electrolysis (g s^–1 m^–2) - w_k2 cathodic corrosion rate for single half-cycle rectified current electrolysis (g s^–1 m^–2) - w _a anodic dissolution rate (g s^–1 m^–2) - w _F theoretical Faradaic dissolution rate (g s^–1 m^–2) - w dissolution rate for alternating current electrolysis (g s^–1 m^–2) - j electric current density (A m^–2)     

Isolation,identification, and synthesis of sex pheromone components of female tea cluster caterpillar,Andraca bipunctata walker (Lepidoptera: Bombycidae) in Taiwan

Octadecanal (18:Ald), (E)-11-octadecenal (E11–18:Ald), (E)-14-octadecenal (E14–18:Ald) and (E,E)-11,14-octadecadienal (E11,E14–18:Ald) were isolated and identified as major components from the pheromone glands of the tea cluster caterpillar,Andraca bipunctata, in Taiwan by analyzing the mass spectra of gland components and their DMDS adducts. GC retention times and mass spectra of the components were in agreement with those of authentic synthetic compounds. The average amount of 18:Ald,E11–18:Ald,E14–18:Ald andE11,E14–18:Ald per female gland (1 to 3 days old) was 121±76, 50±20, 187±75, and 237±110 ng, respectively, in a ratio of 20:8:31:41. SyntheticE11,E14–18:Ald caught more males than each of the other three components or blank control in field trapping tests.E11,E14–18:Ald is reported as an insect sex pheromone for the first time. Male antenna responded toE11,E14–18:Ald strongly in an EAG analysis. Furthermore, 4 hr after the injection of PBAN (pheromone biosynthetic activating neuropeptide) into decapitated female moths (2 days old), the percentage of theE11,E14–C18 Ald in the gland extract increased from 0% to 75.5%, which was also significantly more than that of unligated and uninjected control at 55.1%. All these data indicated thatE11,E14–18:Ald is the sex pheromone of theAndraca bipunctata in Taiwan.     

Preparation and characterization of novel main-chain azobenzene polymers via step-growth polymerization based on click chemistry

A novel α-azide and ω-alkyne A–B type azobenzene monomer, 3′-ethynylphenyl[4-(4-azidobutoxy)phenyl]azobenzene (EAPA), was synthesized and used to generate a novel polymer via step-growth polymerization using 1,3-dipolar cycloaddition reaction under the catalysis of CuSO₄·5H₂O/sodium ascorbate/H₂O (“Click” chemistry). The structure of the resultant main-chain azobenzene polymer, PEAPA, was characterized by GPC, ¹³C NMR, UV–vis and FT-IR spectra. Thermal stability and crystallinity of PEAPA powder were studied by TGA and WAXD. The photo-induced trans–cis isomerization of PEAPA and EAPA in N,N′-dimethyl formamide (DMF) solution was investigated. Furthermore, the thermal cis–trans isomerizations of PEAPA and EAPA were also observed at 60 °C in dark. Thermal stability and trans–cis–trans isomerization behavior of PEAPA was compared with its non-triazole analog, PDHA.     

Differences in sex pheromone communication systems of closely related species:Spodoptera latifascia (walker) andS. descoinsi lalannecassou & silvain (Lepidoptera: Noctuidae)

S. latifascia andS. descoinsi are closely related species that occur sympatrically over limited areas in French Guiana. We examined allopatric populations,S. latifascia originating from Barbados andS. descoinsi from French Guiana. Studies on nocturnal activity cycles showed temporal partitioning of female calling behavior, male sexual activity, and mating behavior.S. descoinsi were sexually active in the first half of the scotophase whereasS. latifascia were sexually active in the second half. Seven compounds (Z9–14: Ac,Z9,E12–14: Ac,Z11–16: Ac,E9,E12–14: Ac,Z9–14: Ald,Z9,E11–14: Ac andZ11–14: Ac) were identified in females of bothS. latifascia andS. descoinsi extracts.Z9–14: Ac was a main pheromone component for the two species. The major difference between the pheromones ofS. latifascia andS. descoinsi was the proportion ofZ9,E12–14: Ac in the extracts: 7% forS. latifascia and 42% forS. descoinsi. The proportion ofZ9,E12–14: Ac relative to the sum ofZ9–14: Ac andZ9,E12–14: Ac in individual gland extracts was 4±1% (mean ± standard deviation) forS. latifascia and 44.8±6% forS. descoinsi. Electrophysiological studies showed no major differences between species in the morphology and physiology of the pheromone receptors of males. Receptors were identified forZ9–14: Ac andZ9,E12–14: Ac, but no receptor was found for the other compounds. In the wind tunnel, synthetic blends withZ9–14: Ac andZ9,E12–14: Ac gave the same behavioral responses as conspecific female extracts for the males of the two species. Some cross-attraction was observed with synthetic blends and female extracts. Nethertheless, previous field trapping experiments in French Guiana were species-specific and suggested differences in the attractivity of males. In the laboratory,S. latifascia andS. descoinsi could hybridize in both reciprocal crosses. FemaleS. descoinsi × maleS. latifascia mating rate was significantly lower than for the reciprocal cross, and 26.7% of femaleS. descoinsi could not separate from maleS. latifascia after mating. These copulatory problems may involve genital incompatibilities between males and females. Several barriers against interbreeding betweenS. latifascia andS. descoinsi seem to combine including differences in nocturnal activity cycles, pheromone differences, and genital barriers. The study of sympatric populations will be necessary to define the role of sex pheromones in the reproductive isolation ofS. latifascia andS. descoinsi.