Variability of vibratory signals and mate choice selectivity in the southern green stink bug.

The southern green stink bug, Nezara viridula, has a complex mate recognition system that implicates chemical and acoustic signals. To localise a sexual partner acoustically, a male and female alternate between the male courtship song (MCrS) and the female calling song type 1 (FCS1). Although previous research has revealed that both signals show geographical variability, until now no studies have explored the form of this variability. We analysed the temporal and spectral characteristics of MCrS and FCS1 pulse trains of males and females from a French and a Guadeloupe population. Pulse train duration of the MCrS varied within and between populations. Likewise, spectral and temporal parameters of FCS1 varied within and between the two populations. Although females did not show any behavioural responses to pre-recorded MCrS, males responded to pre-recorded FCS1 by emitting a higher number of MCrS per minute. Furthermore, males modulated the repetition rate of their MCrS pulse trains to match those of the FCS1. All males responded to FCS1 from French and Guadeloupe females despite the temporal differences in these songs; however, they responded with a shorter latency and a higher rate of MCrS/FCS1 pulse trains to the songs of females from their own population. In choice experiments with two alternatives, responses to FCS1 were inhibited when males received a simultaneous female call from another Pentatomidae sympatric species, Acrosternum hilare. We conclude that, although males prefer FCS1 from their own population, they recognise FCS1 from French and Guadeloupe N. viridula females as species-specific female calls. Variability of vibratory signals might play a role in mate choice.

Asymmetrical generalisation between pheromonal and floral odours in appetitive olfactory conditioning of the honey bee (Apis mellifera L.).

The capacity to generalise between similar but not identical olfactory stimuli is crucial for honey bees, allowing them to find rewarding food sources with varying volatile emissions. We studied bees' generalisation behaviour with odours having different biological values: typical floral odours or alarm compounds. Bees' behavioural and peripheral electrophysiological responses were investigated using a combined proboscis extension response conditioning-electroantennogram assay. Bees were conditioned to pure linalool (floral) or to pure isoamyl acetate (alarm) and were tested with different concentrations of both compounds. Electrophysiological responses were not influenced by conditioning, suggesting that the learning of individual compounds does not rely on modulations of peripheral sensitivity. Behaviourally, generalisation responses of bees conditioned to the alarm compound were much higher than those of bees conditioned to the floral odour. We further demonstrated such asymmetrical generalisation between alarm and floral odours by using differential conditioning procedures. Conditioning to alarm compounds (isoamyl acetate or 2-heptanone) consistently induced more generalisation than conditioning to floral compounds (linalool or phenylacetaldehyde). Interestingly, generalisation between the two alarm compounds, which are otherwise chemically different, was extremely high. These results are discussed in relation to the neural representation of compounds with different biological significance for bees.

Pheromone response inhibitors of the corn stalk borer Sesamia nonagrioides. Biological evaluation and toxicology.

The behavioral activity of some trifluoromethyl ketones (TFMKs) as inhibitors of the pheromone activity of the corn stalk borer Sesamia nonagrioides (Lef.) (Lepidoptera: Noctuidae) is reported. The most closely-related analogue to the pheromone tested, (Z)-11-hexadecenyl trifluoromethyl ketone (Z11-16:TFMK), elicited a significant decrease in the number of male catches in traps baited with mixtures with the pheromone in 1:1 and 10:1 ratios in comparison to the pheromone alone. The E isomer of the analogue as well as two highly hydrated ketones, 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP) and 1,1-difluoropentadecyl trifluoromethyl ketone, were inactive. Conversely, the saturated TFMKs n-dodecyl trifluoromethyl ketone and, particularly, n-hexadecyl trifluoromethyl ketone induced a synergistic effect when mixed with the synthetic pheromone in 10:1 ratio. However, in a wind tunnel these chemicals did not elicit any differential effect on flying moths attracted to a source containing a 10:1 blend of the analogue and the pheromone. In a dual choice bioassay with two dispensers, containing the pheromone alone, and mixtures of Z11-16:TFMK and the pheromone and separated 5 cm apart, males showed no particular preference for either dispenser. The ketone mixture, however, induced moths to execute erratic flights with frequent crosswind counter-turns and intersections with plume boundaries. The total number of contacts with the source were reduced when a control dispenser was paired with a dispenser containing Z11-16:TFMK and pheromone. Z11-16:TFMK and OTFP showed little toxicity on mice with a LD50 of 1 g/kg after the 6th day of treatment. For comparitive purposes, the major component of the pheromone, Z11-16:Ac, displayed a LD50 of 5 g/kg 6 days after application. Our results provide additional information about the activity of the TFMKs, which might be useful for the utilization of these chemicals in future pest control studies.

Biogenic amines modulate olfactory receptor neurons firing activity in Mamestra brassicae.

The modulatory effects of the biogenic amines octopamine and serotonin on pheromonal receptor neurons of Mamestra brassicae were investigated. The responses to sex pheromone components of two cells types (A and B) in single male long sensilla trichodea were monitored. Cell types A and B do not respond to the same compound. The response of type A to a pulse of the major sex pheromone component increased 5 min after octopamine injection. Responses of type B to other odorants increased after 30 min. In the absence of any pheromone stimulation the background firing activity of type A increased following octopamine injection. This background activity was used to evaluate the kinetics of octopamine and other biogenic amine effects on olfactory receptor neurons. Octopamine increased this background activity in a concentration- and time-dependent manner. Clonidine, an octopamine agonist, was shown to be more powerful in increasing the background activity of olfactory receptor neurons. The effects of octopamine and clonidine were hypothesized to arise from specific receptor activation as chlorpromazine (an octopamine antagonist) was shown to block the effect of octopamine. Serotonin, a known neuromodulator in most animal species, induced a reversible inhibition of spike firing. Altogether, these results indicate that biogenic amines can modulate the sensitivity of olfactory receptor neurons of moths either directly or by an action on adaptation.

Asymmetric synthesis of both enantiomers of point-difluorinated-eldanolide, analogues of insect sex pheromone.

Substitution of two fluorine atoms on organic molecules is expected to alter both chemical reactivity and biological activity due to the strong electron-withdrawing nature of fluorine. The synthesis of partly gem-difluorinated compounds remains a significant challenge to synthetic organic chemists. We report that [2,3]-Wittig rearrangement of 1,1,2-trifluoroallylic ether gave a new type of partly gem-difluorinated allylic alcohol: 6-methyl-4,4,5-trifluorohept-1,5-dien-3-ol, 3, in a highly stereoselective fashion, and optical resolution of alcohol 3 was accomplished via lipase PS(PCL)-catalyzed reaction. Using this alcohol as the starting material, the first asymmetric synthesis of both enantiomers of point-fluorinated-eldanolides, 2,2,5,5,6-pentafluoroeldanolide 1 and 5,5,6-trifluoroeldanolide 2, analogues of the sex pheromone of the male African sugarcane borer, has been demonstrated.

Insect parapheromones in olfaction research and semiochemical-based pest control strategies.

The possibility of disrupting the chemical communication of insect pests has initiated the development of new semiochemicals, parapheromones, which are anthropogenic compounds structurally related to natural pheromone components. Modification at the chain and/or at the polar group, isosteric replacements, halogenation or introduction of labeled atoms have been the most common modifications of the pheromone structure. Parapheromones have shown a large variety of effects, and accordingly have been called agonists, pheromone mimics, synergists and hyperagonists, or else pheromone antagonists, antipheromones and inhibitors. Pheromone analogues have been used in quantitative structure-activity relationship studies of insect olfaction, and from a practical point of view they can replace pheromones when these are costly to prepare or unstable under field conditions.

Analytical studies of Spodopteralittoralis sex pheromone components by electroantennography and coupled gas chromatography-electroantennographic detection.

In this paper we present analytical studies of the sex pheromone components of the Egyptian armyworm Spodoptera littoralis (Lepidoptera, Noctuidae) by electroantennography (EAG) and coupled gas chromatography-electroantennographic detection (GC-EAD). EAG responses in three different preparations, using an insect's head, an excised antenna and a live insect, have been recorded. EAG depolarizations of live insects were significantly higher than those elicited by the insect's head or the excised antenna. The responses were dose-dependent. Live insects also allowed regular pheromone stimulations for 40 min with only 38% decrease of the EAG initial depolarization. The synthetic pheromone blend elicited the highest EAG activity (2.0+/-0.3 mV), followed by the major compound (Z,E)-9,11-tetradecadienyl acetate (I) (1.54+/-0.1mV), and the minor components (Z)-9-tetradecenyl acetate (II), (E)-11-tetradecenyl acetate (III), tetradecyl acetate (IV) and (Z)-11-tetradecenyl acetate (V) (1.21-1.32 mV range). (Z,E)-9,12-tetradecadienyl acetate (VI), although not present in the pheromone blend of our strain, also showed an EAG activity (1.32+/-0.09 mV) similar to that of the monoenic components. GC-EAD responses confirmed the composition of the sex pheromone blend, the major response being elicited by the main component I followed by the other minor compounds II-V. The new dienic compound found in the female pheromone gland, (E,E)-10,12-tetradecadienyl acetate (VII), was not electrophysiologically active. Regarding sensitivity, the minimum amount detectable to elicit an antennal response in our GC-EAD system was 15 pg of the major component. In our system, which was built with cheap and easily available materials, no cooling of the effluent at the outlet of the chromatographic column is required.

Pheromone-triggered orientation flight of male moths can be disrupted by trifluoromethyl ketones.

In a wind tunnel trifluoromethyl ketones (TFMKs) have been found to disrupt the orientation flight of male moths to pheromone sources (virgin females or synthetic pheromone). This is demonstrated by comparison of the flight parameters of the Egyptian armyworm Spodoptera littoralis and the Mediterranean corn borer Sesamia nonagrioides, which had been topically treated with TFMKs, with those calculated for untreated insects. Inhibition occurred in all types of behavior and that of the source contact has been quantified and found to be dose-dependent. The same effect has also been noticed in Mediterranean corn borer males flying to an attraction source consisting of mixtures of (Z)-11-hexadecenyl trifluoromethyl ketone (8), a closely related analogue of the major component of the pheromone, and the natural pheromone blend. The most active TFMKs are those closest in structure to the natural pheromone, along with those chemicals which easily hydrate in solution, such as the beta-thiosubstituted derivatives. Along with the previously reported reduction of catches in the field, our results suggest the possible application of these chemicals in future new pest control strategies.

Actographic analysis of the effects of an esterase inhibitor on male moth responses to sex pheromone.

The effects of 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP), a trifluoromethyl ketone that inhibits antennal esterases, on male Mamestra brassicae responses to the main pheromone component have been investigated using an actograph. This actograph used a movement detector based on the Doppler effect. The signal from the detector was digitalized and analysed on a PC microcomputer to quantify male activity. When added to the air flowing through the observation chamber, OTFP inhibited the responses of male moths to the pheromone. The number of males responding to the pheromone and the intensity of the response were decreased by OTFP. The latency of the response was increased and its duration decreased. These effects on the kinetics of the behavioural response cannot be directly correlated to the inhibition of pheromone catabolism by OTFP and other targets must be involved. The high level of inhibition of behaviour observed in presence of OTFP demonstrates the interest of trifluoromethyl ketones as mating disruption agents for pest control.

Effects of trifluoromethyl ketones and related compounds on the EAG and behavioural responses to pheromones in male moths.

Trifluoromethyl ketones (TFMKs) and analogues affect pheromone detection and behaviour in male moths. 3-Octylthio-1,1,1-trifluoropropan-2-one (OTFP), one of the most effective antiesterase agents, decreased the EAG amplitude and increased the repolarization time in Spodoptera littoralis. It also modified EAG responses of Mamestra brassicae and Heliothis zea to their pheromones and analogues, containing an acetate, an alcohol or an aldehyde function. In addition, OTFP also reduced the amplitude of the EAG response to linalool, a monoterpenic alcohol, but not its kinetics. The responses of male S. littoralis to the pheromone in the wind tunnel were significantly reduced after pre-exposure to vapours of OTFP. Comparison of the activity of other TFMKs and analogues with that of OTFP revealed a good agreement on EAG and behaviour. The effects of TFMKs on the EAG kinetics are discussed considering the hypothesis of an inhibition of the pheromone deactivation in the antenna.

Behavioral responses ofSpodoptera littoralis males to sex pheromone components and virgin females in wind tunnel.

The major component of the sex pheromone of femaleSpodoptera littoralis, (Z,E)-9,11-tetradecadienyl acetate (1), elicited all steps of the male behavioral sequence, i.e., wing fanning and taking flight, oriented upwind flight and arrival to the middle of the tunnel, close approach and contact with the source. The activity was equivalent to that elicited by virgin females. In the range of doses tested, the dosage of1 had no significant effect on the number of source contacts. Male response was significantly affected by light intensity, being optimum at 3 lux. Activity of the minor components (Z)-9-tetradecenyl acetate (2), (E)-11-tetradecenyl acetate (3), tetradecyl acetate (4), (Z)-11-tetradecenyl acetate (5), and (Z,E)-9,12-tetradecadienyl acetate (6) was significantly lower than that of the major component when assayed individually. In multicomponent blends compound4 appeared to strongly decrease the number of males arrested at the source, the effect being particularly important when compound5 was present in the blend. Results of single sensillum experiments confirmed the existence of two main physiologically distinct sensillar types. The most common type of sensilla contained a neuron that responded specifically to compound1. A second type of sensilla, located laterally on the ventral sensory surface, contained two receptor neurons responding to compound6 and to (Z)-9-tetradecenol. Among short sensilla, one hair responded to compound4 and could represent a minor sensillar type. No sensory neuron was found to detect the other minor pheromone compounds2, 3, and5.

Sulfhydryl-reagent inhibition of olfaction in a moth and effects of exposure to pheromone compounds or a pheromone analogue.

The effects on olfaction of N-ethylmaleimide (NEM), a specific reagent of free sulfhydryl groups, were studied in the moth Mamestra brassicae. The antennae of male M. brassicae bear two types of specialist receptor neurons involved in pheromone communication. One type is tuned to (Z)-11-hexadecenyl acetate (Z11-16:Ac), the main pheromone component; the second type is tuned to (Z)-9-tetradecenyl acetate (Z9-14:Ac), an interspecific inhibitor not produced by the females of this species. Vapours of NEM irreversibly inhibited the electro-antennographic (EAG) responses to Z11-16:Ac and Z9-14:Ac. When Z11-16:Ac was applied before and during NEM treatment, the responses to Z9-14:Ac were preserved and some protection was observed in the responses to Z11-16:Ac. In return, Z9-14:Ac partially prevented the disappearance of responses to Z11-16:Ac but not to Z9-14:Ac. A third compound, hexadecyl acetate (16:Ac), found in the pheromone gland, but not detected by the antennal receptors, did not prevent the inhibition caused by NEM.

Bisabolene epoxides in sex pheromone innezara viridula (L.) (Heteroptera: Pentatomidae): Role ofcis isomer and relation to specificity of pheromone.

Thetrans- andcis-(Z)-α-bisabolene epoxides (trans- andcis-(Z)-αBE) are the main components of the male sex pheromone inNezara viridula. The role of thecis isomer and the importance of thecis/trans proportion for the activity and the specificity of the pheromone are not clearly elucidated and were studied here. Interindividual variation of thecis/trans proportion produced by males was studied by individual hexanic extracts in two strains originating from the south of France (SF) and French West Indies (FWI). Thetrans isomer composed 42-82% of bisabolene epoxides in SF males and 74-94% of bisabolene epoxides in FWI males. Means (± SD) significantly differ between SF (62.8%±8.4) and FWI (82.4%±5.9) males in spite of this interindividual variation. Different isomers of bisabolene epoxide were synthesized and their EAG activity on female antennae was compared. Racemictrans- andcis-(Z)-αBE elicited low EAGs, not different from the nonnaturaltrans andcis (E)-αBE that were inactive on behavior. Behavioral tests revealed that racemictrans- andcis-(Z)-αBE attracted 45% (P<0.05) and 25% (P<0.05) of females, respectively. The same levels of attraction were obtained with (-) enantiomers oftrans- andcis-(Z)-αBE, which attracted 40% (P<0.05) and 20% (P>0.05) of the females, respectively. Binary blends containing 75/25, 50/50, and 25/75 proportions ofcis/trans isomers were more attractive thantrans-(Z)-αBE alone and response of females to the 25%cis/75%trans blend was significantly more important than the response totrans-isomer alone (P<0.05). The importance of thecis/trans proportion in relation with the specificity of the male pheromone is discussed.

Electrophysiological and field activity of halogenated analogs of (E,E)-8,10-dodecadien-1-ol, the main pheromone component, in codling moth (Cydia pomonella L.).

Pest monitoring and control of the codling moth,Cydia pomonella L., have been developed using the main pheromone component of this species, (E,E)-8,10-dodecadienol (codlemone). However, the activity of codlemone is not satisfactory for pest control by mating disruption. Thus, we have synthesized halogenated analogs of codlemone to see if they could be used as new agents for pest control of the codling moth. Their biological activity was measured by electrophysiological techniques. In EAG screening, codlemone was the most active compound. F(10,11)-codlemone [(E,E)-10,11-difluoro-8,10-dodecadienol] and Cl-codlemone [(E,E)-11-chloro-8,10-undecadienol] elicited significant EAG responses, F(10,11)-codlemone triggering responses not significantly different from responses to codlemone. EAG cross-adaptation experiments and single sensillum recordings revealed that these compounds were detected by the same receptor neuron type as codlemone. No competitive inhibition with codlemone was observed from nonactive compounds. In field trapping, F(10,11)-codlemone and Cl-codlemone were more attractive to male codling moths than codlemone itself. Possible explanations of this activity are discussed.

Sex pheromone of the european sunflower moth,Homoeosoma nebulellum (Den. & Schiff.) (Lepidoptera: Pyralidae).

Four components, (Z)-9-tetradecenal (8.6%), (Z,E)-9,12-tetradecadienal (4.8%), (Z)-11-hexadecenal (49.5%), and (Z)-13-octadecenal (37.1%), were identified in extracts of female pheromone glands of the European sunflower moth,Homoeosoma nebulellum (Lepidoptera: Pyralidae) using GC and GC-MS analyses. EAG and single-cell recordings of male antennal receptors gave strong evidence for (Z,E)-9,12-tetradecadienal as the antennal key compound of sex pheromone detection in this species. This result was confirmed by field trapping; removal of (Z,E)-9,12-tetradecadienal from quaternary blends completely suppressed the male catches. The synthetic blends with this compound as a major component caught five times less males than the blends reproducing the ratio found in the female extracts [5% of (Z,E)-9,12-tetradecadienal only]. The occurrence of a minor component perceived as the most biologically relevant compound is discussed.

Male-produced aggregation pheromone of the american palm weevil,Rhynchophorus palmarum (L.) (Coleoptera, Curculionidae): Collection, identification, electrophysiogical activity, and laboratory bioassay.

Male American palm weevils (APWs),Rhynchophorus palmarum (L.) produced two sex-specific compounds, which were disclosed by volatile collections on Supelpak-2 and gas chromatography. One was a minor compound, not always detected. The major male-produced volatile was identified as (2E)-6-methyl-2-hepten-4-ol through coupled gas chromatography-mass spectrometry and gas chromatography-Fourier transform infrared spectrometry, proton nuclear magnetic resonance spectrometry, and rational synthesis. We propose the trivial name rhynchophorol for this new molecule, which proved to be the essential component of the APW aggregation pheromone by electroantennography, coupled gas chromatography-electroantennography and behavioral bioassays.

Multivariate analysis of the correlation between noctuidae subfamilies and the chemical structure of their sex pheromones or male attractants.

Female-emitted pheromones and sex attractants of Noctuidae were investigated using a specific computer procedure to analyze data collected from the literature. Correspondence analysis was used to survey the structure-activity relationships of sex pheromones in seven subfamilies. Structural, stereochemical, and functional features of active molecules were related to taxonomy. This multidimensional analysis revealed that the prevalent chemical frame of noctuid moth pheromones was a monounsaturated acetate withZ stereochemistry and a double bond on the fifth carbon closest to the nonfunctional branch of the molecule. Possible phylogenetic relationships within Noctuidae and between Noctuidae and other families are discussed in light of the sex pheromone biochemistry. Female sex pheromones appeared to be an additional character to be considered in the classification of noctuid moths.

The manpower debate -- what is the current position in relation to general practice?

With the changing situation in medical manpower, it is important that a close watch be kept on the total number of medical practitioners in the community and their distribution between salaried and self-employed work, between hospital and community practice, between city and country practice, between general and specialist practice and between the general specialties and subspecialties. More accurate manpower data are now being sought by the Medical Boards and what must be emphasized is that the collection of these data has to be regular and ongoing, with surveys being conducted each year at the time of registration, and not just spasmodically as the need arises. The groups involved in planning for medical manpower must be able to work with accurate information. Australia is a long way from defining how many medical practitioners are needed in the community, and the RACGP is certainly a long way from defining the number of general practitioners who are needed. As a result, it is probably inappropriate at present to evaluate the current numbers of general practitioners against any stated level of adequacy.

[A study of the lower urinary apparatus using 105 mm ampliphotography (author's transl)]. / Etude du bas appareil urinaire dn ampliphotographie 105 mm

The exploration of the lower urinary apparatus was carried out using a 105 mm ampliphotography system. 230 examinations were performed according to several techniques: descending and micturition cystography; urethrocystography or retrograde and voiding cystography; cystography with suprapublic puncture; and cystometrography. An analysis of the results enabled an evaluation of the method. The morphological study may appear inadequate if electronic enlargement is not employed. The dynamic study is excellent in the diagnosis of diseases of the neck and uretheral stenosis. The limits of the amplifier field should not lead to a failure to recognize a possible vesicoureteral reflux. A decrease in the exposure dose makes it a technique of choice in children on the condition that the rate of exposures is not excessive and electronic enlargement is not performed too frequently.