Sex pheromone blend of Manduca sexta: Responses of central olfactory interneurons to antennal stimulation in male moths

Recently, chemical analysis of solvent rinses of the external surfaces of pheromone glands from female Manduca sexta revealed a blend of 12 aldehydes, including the previously identified sex pheromone component, (E,Z)-10,12-hexadecadienal (bombykal). Previous electrophysiological studies showed that olfactory (deutocerebral) interneurons in the antennal lobes of males exhibited a wide range of responsiveness to pheromonal stimulation of the ipsilateral antenna. These experiments were performed with crude extracts of pheromone glands as well as two synthetic compounds: the major pheromone component, bombykal, and (E,Z)-11,13-pentadecadienal, a mimic of a second component of the female's pheromone blend. Using intracellular methods, we have now reexamined similar olfactory interneurons, using each of the 12 chemically identified components as well as synthetic blends of various combinations of them. Eight of the 12 components isolated from female glands elicited some form of response in olfactory interneurons in males. In accordance with biochemical and behavioral data, the most potent are bombykal and two trienals, (E,E,E)- and (E,E,Z)-10,12,14-hexadecatrienal. We also conclude that the C₁₅ dienal is selective for one of the trienal receptors on the antenna, but is much less potent than the natural trienal stimulant.     

Frequency filter properties of lobster chemoreceptor cells determined with high-resolution stimulus measurement

1. We developed a high resolution, on-line stimulus measurement system for accurate control of chemical stimulus applications for Homarus americanus lateral antennule chemoreceptors. Focal stimulus presentations in an electrophysiological preparation with the receptor sensilla intact were measured at small spatial (30 μm) and time (5 ms) scales.
2. We tested 15 receptor cells with ten 100 ms pulses of 10⁴ M hydroxyproline at 0.5, 1, 2 and 4 Hz and with a single 8 s square pulse. Individual cells showed differences in their capabilities to resolve pulses (“flicker fusion”). At 2 Hz stimulation, some cells could follow stimulus pulses while others could not. At 4 Hz, 3 cells could still encode individual stimulus pulses accurately. The population resolved pulses up to 2 Hz; at 4 Hz, the population response to a pulse series approximated the response to a square pulse.
3. Repetitive stimulation caused a gradual decrease in the number of spikes and a gradual increase in first spike latency (“cumulative adaptation”). Increased stimulation frequency resulted in greater cumulative adaptation.
4. Since individual differences in adaptation and disadaptation rates of the receptor cells could not be attributed to measured stimulus variability in situ, lobster chemoreceptor cell populations have intrinsic temporal diversity which, we hypothesize, could be used to analyze pulsatile stimuli that occur in natural turbulent odor plumes.

     

Resolution of pheromone pulses in receptor cells of Antheraea polyphemus at different temperatures

The ability of pheromone receptor cells of male Antheraea polyphemus (Saturniidae) to resolve stimulus pulses was determined at different temperatures (8°, 18°, 28°C). The cells were stimulated by repeated 20-ms puffs of the pheromone components (E, Z)-6, 11-hexadecadienyl acetate and (E, Z)-6,11-hexadecadienal. At higher temperatures, higher frequencies of stimulus pulses were resolved by the nerve-impulse response: about 1.25 pulses per second at 8°C, 2.5 pulses/s at 18°C and 5 pulses/s at 28°C. The decreased ability of receptor cells to resolve stimulus pulses at low temperatures may reduce the male moth's chance of reaching the pheromone source. The peak nerve-impulse frequency increased whereas the duration of nerve-impulse responses to single stimulus pulses decreased at higher temperatures. At a given temperature and stimulus intensity the peak nerveimpulse frequency decreased with shorter intervals between the stimulus pulses, but the duration of the responses remained almost constant. The time needed for recovery from adaptation caused by a single stimulus pulse was longer at lower temperatures. The aldehyde receptor cell recovered more quickly than the acetate cell. At low stimulus concentration, the resolution ability of the acetate cell was strongly decreased, whereas in the aldehyde cell it was only slightly impaired.     

Temporal resolution in olfaction III: flicker fusion and concentration-dependent synchronization with stimulus pulse trains of antennular chemoreceptor cells in the American lobster

To understand how chemoreceptor organs may extract temporal information from odor plumes, we investigated the frequency filter properties of lobster chemoreceptor cells. We used rapid stimulation and high-resolution stimulus measurement for accurate stimulus control and recorded extracellular responses from chemoreceptors in the lobster lateral antennule in situ. We tested 16 hydroxyproline-sensitive cells with a series of ten 100-ms pulses at 10, 100 and 1000 μmol l⁻¹ at stimulation frequencies from 0.5 Hz to 4 Hz. Receptor cell responses could accurately encode 10 μmol l⁻¹, but not 100 or 1000 μmol l⁻¹ pulses, delivered at rates of 4 Hz. Flicker-fusion frequency and synchronization with the stimulus pulse train were concentration dependent: performance rates above 1 Hz became poorer both with increasing pulse amplitude and frequency. Flicker fusion frequency was 3 Hz for 100 μmol l⁻¹ pulses and 2 Hz for 1000 μmol l⁻¹ pulses. Individual cells showed differences in their stimulus pulse following capabilities, as measured by the synchronization coefficient. These individual differences may form a basis for coding temporal features of an odor plume in an across-fiber pattern. Accepted: 7 July 1999     

(Z)-3-nonenol, (Z,Z)-3,6-nonadienol and (S,S)-(-)-epianastrephin: male produced pheromones of the Mexican fruit fly

(Z)-3-nonenol, (Z,Z)-3,6-nonadienol and (S,S)-(-)-epianastrephin proved active as male-produced pheromones which elicited behavioral responses from virgin female Mexican fruit flies (Anastrepha ludens) (Diptera: Tephritidae) in laboratory bioassays. All three chemicals elicited attraction and/or locomotor arrest when tested individually. When tested together, (Z)-3-nonenol inhibited the behavioral effect of (Z,Z)-3,6-nonadienol but either of the alcohols synergized the effect of (S,S)-(-)-epianastrephin. Quantities of the pheromones per male abdomen were: (Z)-3-nonenol-100 ng; (Z,Z)-3,6-nonadienol-40 ng; and total epianastrephin (R,R and S,S enantiomers)-700 ng. Relative to the quantities in abdominal extract, males released these chemicals during sexual display in a blend containing a higher proportion of the alcohols.

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Résumé Le (Z)-3-nonènol, le (Z,Z)-3,6-nonadiènol et le (S,S)-(-)-épianastréphine produits par les mâles de la mouche mexicaine du fruit (Anastrepha ludens) (Diptera: Tephritidae) ont attirés les femelles lors de tests conduits en laboratoire. Le pouvoir attractif du (Z)-3-nonènol est faible comparé à celui des deux autres phéromones. Evalués ensemble, le (Z)-3-nonènol inhibe l'attractivité du (Z,Z)-3,6-nonadiènol mais chacun des deux alcools synergise l'effet attractif de la (S,S)-(-)-épianastréphine. Les quantités recouvrées par mâle dans un extrait abdominal étaient respectivement de 100, 40 et 700 ng pour le (Z)-3-nonènol, le (Z,Z)-3,6-nonadiènol, et l'épianastréphine totale (R,R et S,S) énantiomères. Comparées à ces valeurs, le mélange élange émis par les mâles lors de leur cour sexuelle est plus riche in alcools. Le rapport (Z)-3-nonènol (Z,Z)-3,6-nonadiènol est cependant identique dans l'extrait abdominal et dans le mélange émis par les mâles.

     

Concise Synthesis of (8Z,11Z,14Z)-8,11,14-Heptadecatrienal, (7Z,10Z,13Z)-7,10,13-Hexadecatrienal,and (8Z,11Z)-8,11-Heptadecadienal,Components of the Essential Oil of Marine Green Alga Ulva pertusa

The long-chain aldehydes, (8Z,11Z,14Z)-8,11,14-heptadecatrienal, (7Z,10Z,13Z)-7,10,13-hexadecatrienal, and (8Z,11Z)-8,11-heptadecadienal, were concisely synthesized by using Grignard coupling, catalytic hydrogenation with the Lindlar catalyst, and oxidation with Dess–Martin periodinane as the key steps. Particularly, (8Z,11Z,14Z)-8,11,14-heptadecatrienal and (7Z,10Z,13Z)-7,10,13-hexadecatrienal both possessed a seaweed-like odor.     

Mouse Postganglionic Sympathetic Neurons

Basic properties of noradrenaline release were studied in primary cultures of thoracolumbar postganglionic sympathetic neurons taken from 1-3-day-old NMRI mice. After 7 days in vitro, the cultures were preincubated with [3H]noradrenaline and then superfused and stimulated electrically. Conventional trains of pulses (for example, 36 pulses at 3 Hz) as well as single pulses and brief high-frequency trains (for example, four pulses at 100 Hz) elicited a well-measurable overflow of tritium, which was abolished by 0.3 microM tetrodotoxin or omission of Ca2+, but not changed by 1 microM rauwolscine. In trains of one, two, four, six, eight, or 10 pulses at 3 Hz, the evoked overflow of tritium remained constant from pulse to pulse at 1.3 mM Ca2+, but declined slightly at 2.5 mM Ca2+. Tetraethylammonium at 10 mM selectively increased the overflow elicited by small pulse numbers and especially by a single pulse. In trains of 10 pulses delivered at 0.3, 1, 3, 10, 30, or 100 Hz, the evoked overflow of tritium increased from 0.3 to 30 Hz and then declined at 100 Hz. This relationship was particularly pronounced at low Ca2+ concentrations (for example, 0.3 mM). Tetraethylammonium at 10 mM selectively increased the overflow elicited by low frequencies of stimulation. It is concluded that primary cultures of mouse postganglionic sympathetic neurons can be used to investigate release of [3H]noradrenaline. The release is well measurable, even upon a single electrical pulse. It agrees with release in intact sympathetically innervated tissues in a number of fundamental properties, including the pulse number and frequency dependence. The preparation may be of special interest in conjunction with genetic manipulations in the donor animals.     

Green leaf volatile-detecting olfactory receptor neurones display very high sensitivity and specificity in a scarab beetle

In the Japanese scarab beetle, Phyllopertha diversa, olfactory receptor neurones specific for the detection of so-called general green leaf volatiles (GLV) display a high specificity and sensitivity. Three main types of green-leaf-volatile-detecting receptor neurones specific to (Z)-3-hexenyl acetate, (E)-2-hexenal and (Z)-3-hexenol, respectively, were identified. Each type responded at a very low stimulus concentration to the key stimulus, and required at least a thousand-fold increase in concentration to respond to any of the other GLVs tested. Flower-odour-and pheromone-detecting receptor neurones were also identified. Olfactory sensilla housing plant-odour- or pheromone-detecting receptor neurones displayed clear morphological differences, and were also separated into different antennal regions.     

Electroantennagrams of Mexican fruit flies to chemicals produced by males

Male-produced chemicals were tested on antennae of the Mexican fruit fly (Anastrepha ludens) (Diptera: Tephritidae) using the electroantennagram technique. Male and female antennae responded equivalently to six chemicals and combinations of the six chemicals. (S,S)-(-)-epianastrephin elicited responses two-three times greater than any of the other chemicals, (S,S)-(-)-anastrephin gave greater responses than (R,R)-(+)-anastrephin, and Z,Z-3,6-nonadienol gave greater responses than Z-3-nonenol. The combination of Z,Z-3,6-nonadienol and Z-3-nonenol elicited a response which was slightly less than the response to Z,Z-3,6-nonadienol alone. The EAG data were highly correlated with behavioral data from earlier experiments.

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Résumé L'étude des substances émises par les mâles d'A. ludens (Diptera, Tephritidae) comprenant 2 paires énantiomériques de lactones épimériques et 2 alcools, a été réalisée à partir d'électroantennogrammes.Les antennes des mâles et des femelles ont répondu de la même façon aux 6 substances examinées séparément, ou combinées 2 à 2, ou toutes ensembles. La (S,S)-(-) épianastréphine, seule ou en combinaison, a induit une réponse significativement de 2 à 3 fois plus importante que n'importe qu'elle autre substance. La (S,S)-(-) anastréphine a induit des EAG deux fois plus importantes que ceux obtenus avec la (R,R)-(+) anastréphine.L'importance des réponses aux 4 lactones est liée à leurs relations structurales.Le (Z,Z)-3,6 nonadiénol a provoqué des réponses 2 fois plus importantes que celles du (Z)-3 nonénol, et la combinaison des 2 alcools a induit une réponse légèrement inférieure à celle obtenue avec le (Z,Z)-3,6-nonadiénol seul.Les résultats en EAG sont très conformes aux observations comportementales d'expériences précédentes.

     

Odor Detection in Manduca sexta Is Optimized when Odor Stimuli Are Pulsed at a Frequency Matching the Wing Beat during Flight

Sensory systems sample the external world actively, within the context of self-motion induced disturbances. Mammals sample olfactory cues within the context of respiratory cycles and have adapted to process olfactory information within the time frame of a single sniff cycle. In plume tracking insects, it remains unknown whether olfactory processing is adapted to wing beating, which causes similar physical effects as sniffing. To explore this we first characterized the physical properties of our odor delivery system using hotwire anemometry and photo ionization detection, which confirmed that odor stimuli were temporally structured. Electroantennograms confirmed that pulse trains were tracked physiologically. Next, we quantified odor detection in moths in a series of psychophysical experiments to determine whether pulsing odor affected acuity. Moths were first conditioned to respond to a target odorant using Pavlovian olfactory conditioning. At 24 and 48 h after conditioning, moths were tested with a dilution series of the conditioned odor. On separate days odor was presented either continuously or as 20 Hz pulse trains to simulate wing beating effects. We varied pulse train duty cycle, olfactometer outflow velocity, pulsing method, and odor. Results of these studies, established that detection was enhanced when odors were pulsed. Higher velocity and briefer pulses also enhanced detection. Post hoc analysis indicated enhanced detection was the result of a significantly lower behavioral response to blank stimuli when presented as pulse trains. Since blank responses are a measure of false positive responses, this suggests that the olfactory system makes fewer errors (i.e. is more reliable) when odors are experienced as pulse trains. We therefore postulate that the olfactory system of Manduca sexta may have evolved mechanisms to enhance odor detection during flight, where the effects of wing beating represent the norm. This system may even exploit temporal structure in a manner similar to sniffing.     

Sexual communication in the termite Prorhinotermes simplex (Isoptera, Rhinotermitidae) mediated by a pheromone from female tergal glands

We studied the post-flight behavior and sex attraction in imagoes of the termite Prorhinotermes simplex (Rhinotermitidae, Prorhinotermitinae). Pairing is mediated by the secretion from tergal glands, exposed by females in a calling posture and highly attractive to males. Analysis of extracts of these glands by means of gas chromatography with electroantennographic detection indicated a chromatographic area corresponding to an intense physiological response of males. The retention characteristics of this area proved to be identical with those of (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol. Electroantennographic and behavioral assays revealed that units of picograms of the compound represent a stimulus qualitatively and quantitatively equivalent to one female tergal gland. Thus, we hypothesize that (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol is a major component of the female sex pheromone in P. simplex.     

Processing of sensory signals by a non-spiking neuron in the leech

The non-spiking neurons 151 are present as bilateral pairs in each midbody ganglion of the leech nervous system and they are electrically coupled to several motorneurons. Intracellular recordings were used to investigate how these neurons process input from the mechanosensory P neurons in isolated ganglia. Induction of spike trains (15 Hz) in single P cells evoked responses that combined depolarizing and hyperpolarizing phases in cells 151. The phasic depolarizations, transmitted through spiking interneurons, reversed at around -20 mV. The hyperpolarization had two components, both reversing at around -65 mV, and which were inhibited by strychnine (10 micromol l(-1)). The faster component was transmitted through spiking interneurons and the slower component through a direct P-151 interaction. Short trains (<400 ms) of P cell spikes (15 Hz) evoked the phasic depolarizations superimposed on the hyperpolarization, while long spike trains (>500 ms) produced a succession of depolarizations that masked the hyperpolarizing phase. The amplitude and duration of the hyperpolarization reached their maximum at the initial spikes in a train, while the depolarizations persisted throughout the duration of the stimulus train. Both phases of the response were relatively unaffected by the spike frequency (5-25 Hz). The non-spiking neurons 151 processed the sensory signals in the temporal rather than in the amplitude domain.     

Interval-specific event related potentials to omitted stimuli in the electrosensory pathway in elasmobranchs: an elementary form of expectation

Multiunit activity and slow local field potentials show Omitted Stimulus Potentials (OSP) in the electrosensory system in rays (Platyrhinoidis triseriata, Urolophus halleri) after a missing stimulus in a 3 to >20 Hz train of V pulses in the bath, at levels from the primary medullary nucleus to the telencephalon. A precursor can be seen in the afferent nerve. The OSP follows the due-time of the first omitted stimulus with a, usually, constant main peak latency, 30–50 ms in medullary dorsal nucleus, 60–100 ms in midbrain, 120–190 ms in telencephalon — as though the brain has an expectation specific to the interstimulus interval (ISI). The latency, form and components vary between nerve, medulla, mid-brain and forebrain. They include early fast waves, later slow waves and labile induced rhythms. Responsive loci are quite local. Besides ISI, which exerts a strong influence, many factors affect the OSP slightly, including train parameters and intensity, duration and polarity of the single stimulus pulses. Jitter of ISI does not reduce the OSP substantially, if the last interval equals the mean; the mean and the last interval have the main effect on both amplitude and latency.Taken together with our recent findings on visually evoked OSPs, we conclude that OSPs do not require higher brain levels or even the complexities of the retina. They appear in primary sensory nuclei and are then modified at midbrain and telencephalic levels. We propose that the initial processes are partly in the receptors and partly in the first central relay including a rapid increase of some depressing influence contributed by each stimulus. This influence comes to an ISI-specific equilibrium with the excitatory influence; withholding a stimulus and hence its depressing influence causes a rebound excitation with a specific latency.Abbreviations DN dorsal nucleus of medullary lateral line lobe - EEG electroencephalogram - EP evoked potential - ERP event related potential - IR induced rhythm - ISI interstimulus interval - OSP omitted stimulus potential - MLN mesencephalic lateral nucleus - P75 positive peak at 75 ms     

The habituation of event-related potentials to speech sounds and tones

We examined the short- and long-term habituation of auditory event-related potentials (ERPs) elicited by tones, complex tones and digitized speech sounds (vowels and consonant-vowel-consonant syllables). Twelve different stimuli equated in loudness and duration (300 msec) were studied. To examine short-term habituation stimuli were presented in trains of 6 with interstimulus intervals of 0.5 or 1.0 sec. The first 4 stimuli in a train were identical standards. On 50% of the trains the standard in the 5th position was replaced by a deviant probe stimulus, and on 20% of the trains the standard in the 6th position was replaced by a target, a truncated standard that required a speeded button press response.Short-term habituation (STH) was complete by the third stimulus in the train and resulted in amplitude decrements of 50–75% for the N1 component. STH was partially stimulus specific in that amplitudes were larger following deviant stimuli in the 5th position than following standards. STH of the N1 was more marked for speech sounds than for loudness-matched tones or complex tones at short ISI. In addition, standard and deviant stimuli that differed in phonetic structure showed more cross-habituation than did tones or complex tones that differed in frequency. This pattern of results suggests that STH is a function of the acoustic resemblance of successive stimuli.The long-term habituation (LTH) of the ERP was studied by comparing amplitudes across balanced 5.25 m stimulus blocks over the course of the experiment. Two types of LTH were observed. The N1 showed stimulus-specific LTH in that N1 amplitudes declined during the presentation of a stimulus, but returned to control levels when a different stimulus was presented in the subsequent condition. In contrast, the P3 elicited by the deviant stimuli showed non-specific LTH, being reduced across successive blocks containing different stimuli. P3s elicited by target stimuli remained stable in amplitude.     

Mating calls of three prochilodontid fish species from Brazil

Passive acoustic monitoring (PAM) of fish sounds has been used as a means of detecting the presence and abundance of fishes. Prior to PAM, bioacoustical analyses of sounds are needed to characterize species-specific characteristics of calls. With hydrophones placed in outdoor ponds, we recorded the mating calls of three species of prochilodontid fishes (Prochilodus argenteus, P. costatus, P. lineatus). Fish were induced to spawn and call by injection of carp (Cyprinus carpio) pituitary gland extract. We recorded a total of 394 pulse train calls and additional single pulse calls that were not associated with trains. The trains of all three species were similar in nature - series of low frequency pulses that lasted from 1 to 11 s, often with an initial rapid rise followed by a slow tapering of pulse amplitude. Dominant frequency of single pulses and trains was greatest in P. lineatus, with P. costatus and P. argenteus exhibiting lower single pulse dominant frequencies, and P. costatus having lower train dominant frequency. With data from the three species combined, the dominant frequency of pulses significantly increased with fish standard length. There was also a significant linear relationship between the dominant frequency of pulses and trains. Discriminant function analysis showed that differences in train dominant frequency, pulse duration, and pulse period between the three species were significant enough to discriminate between them. This study was the first to fully characterize the sounds of these three Prochilodus species, and should assist fisheries biologists monitoring spawning behavior in these species.     

Identification and field optimisation of the female sex pheromone of the rice leaffolder,Cnaphalocrocis medinalis in India

Analysis of ovipositor washings from virgin femaleCnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae) of Indian origin by linked gas chromatography and electroantennography indicated the presence of three electrophysiologically-active compounds. These were identified on the basis of their gas chromatographic retention times and mass spectra as (Z)-11-hexadecenyl acetate, (Z)-13-octadecenyl acetate and (Z)-13-octadecen-1-ol with (Z)-13-octadecenyl acetate present in amounts of between 0.25 and 1.5 ng per ovipositor and the other two components at less than 10% of this. Trace quantities of octadecyl acetate were identified by mass spectrometry but no electroantennographic responses were observed to this compound. Field trials conducted with a range of blends of the three electrophysiologically-active compounds showed that blends containing between 5% and 30% (Z)-11-hexadecenyl acetate in (Z)-13-octadecenyl acetate dispensed from either white rubber septa or polythene vials were more attractive to male moths than a virgin female moth. Addition of (Z)-13-octadecen-1-ol reduced attractiveness to male moths in the blends and concentrations tested.     

Components of the female sex pheromone of the yellow stem borer, Scirpophaga incertulas

Ovipositor washings and volatiles from virgin female Scirpophaga incertulas (Walker) (Lepidoptera: Pyralidae) were analysed by gas chromatography (GC) linked to electroantennography (EAG). Two EAG responses were observed at retention times consistent with those of monounsaturated 16-carbon aldehydes and monounsaturated 16-carbon alcohols. Analysis of ovipositor washings on high-resolution, capillary GC columns showed peaks which cochromatographed with (Z)-11-hexadecenal, (Z)-9-hexadecenal, (Z)-11-hexadecen-1-ol and hexadecanal. EAG responses of male S. incertulas to synthetic hexadecenal isomers were greatest for the (Z)-11 and (Z)-11 isomers. Field tests in the Philippines showed that traps baited with a mixture of (Z)-11-hexadecenal and (Z)-9-hexadecenal in the naturally occurring 3:1 ratio caught significantly more male S. incertulas moths than those baited with a virgin female moth. Addition of (Z)-11-hexadecen-1-ol to this mixture reduced trap catches.

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Résumé Des produits provenant du lavage d l'ovipositeur et des substances volatiles de femelles vierges de S. incertulas Walker (Lep.: Pyralidae) ont été examinées en chromatographie en phase gazeuse (GC) avecélectroantennogramme simultané(EAG). Deux réponses EAG ont été enregistrées à des temps de rétention correspondant à ceux des aldéhydes monoinsaturés 16 carbones et des alcools monoinsaturés 16 carbones. L'analyse des produits provenant du lavage de l'ovipositeur en colonnes GC capillaires à haute résolution a donné des pics correspondant aux (Z)-11-hexadécenal, (Z)-9-hexadécenal, (Z)-11-hexadecen-1-ol et à l'hexadecanal. Les réponses EAG de mâles de S. incertulas aux isomères synthétiques d'hexadécenal étaient plus intenses pour les isomères (Z)-11 et (E)-11. Des essais en champ aux Philippines ont montré que les pièges contenant un mélange de (Z)-11-hexadécenal et de (Z)-9-hexadécenal dans le rapport natural 3/ 1 capturaient plus de mâles de S. incertulas que ceux contenant une femelle vierge. L'addition au mélange de (Z)-11-hexadecen-1-ol réduit les captures.

     

CHARACTERISTICS OF MINKE WHALE (BALAENOPTERA ACUTOROSTRATA) PULSE TRAINS RECORDED NEAR PUERTO RICO

A nine-day acoustic and visual survey was conducted off the West Indies in March 1994 to study the pulse trains that were detected on SOSUS arrays throughout winter in deep water between the West Indies and Bermuda. During the survey, pulse train sounds were consistently recorded in an area 190–350 km northeast of Puerto Rico. Vocalizing animals were never visually observed, but visual sighting conditions were often poor and observation height was low. Pulse trains occurred in two basic forms. The "speed-up" pulse train was characterized by an accelerating series of pulses with energy in the 200–400 Hz band, with individual pulses lasting 40-60 msec. Speedup pulse trains started with average pulse rates of 1.5 pulses/sec, lasted 43.7 ± 6.0 sec, and ended with average pulse rates of 2.8 pulses/sec. The less common "slow-down" pulse train was characterized by a decelerating series of pulses with energy in the 250-350 Hz band. Slow-down pulse trains started at pulse rates averaging 4.5 pulses/sec, lasted 60.9 ± 5.8 sec, and ended with average pulse rates of 2.9 pulses/sec. We believe the recorded pulse trains are from minke whales based on careful reanalysis of, and comparison to, minke whale pulse-train sounds recorded in the Caribbean by Winn and Perkins (1976).     

Hickory shuckworm Cydia caryana: electroantennogram and flight tunnel studies of potential sex pheromone components

Electroantennogram (EAG) measurement of male Cydia caryana moth antennal olfactory response to monounsaturated 12 and 14 carbon alcohols and acetates indicated that the (E)-8-, (E)-10- conjugated double bond system of a dodecadien-1-ol acetate is a critical chemical structural component of the C. caryana sex pheromone. Additionally, EAG measurements implicated (E)-8-dodecen-1-ol acetate, (Z)-8-dodecen-1-ol acetate, (Z)-9-dodecen-1-ol acetate and (Z)-12-tetradecen-1-ol as potential minor pheromonal components. An EAG dosage-response study suggested that there were at least two heterologous populations of pheromone acceptors. Behavioral analysis of male moth response in a flight tunnel to compounds which evoked the stronger EAG responses suggested that (E,E)-8,10-dodecadien-1-ol acetate and (Z)-9-dodecen-1-ol acetate resemble or are C. caryana sex pheromonal components, while (Z)-8-dodecen-1-ol acetate and (E)-10-dodecen-1-ol acetate are either parapheromones or are minor pheromone components. Behavioral significance of (Z)-12-tetradecen-1-ol was difficult to interpret in the flight tunnel.

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Résumé Les réponses olfactives antennaires de Cydia caryana, mesurées par électroantennogrammes (EAG), aux alcools et acétates à carbones monounsaturés en positions 12 et 14, ont montré que le système conjugué de double liaison, (E)-8-, (E)-10- du dodecadien-1-ol acétate constitue un composé chimique strutural critique de la phéromone sexuelle de C. caryana.De plus, les acétates: (E)-8-dodecen-1-ol,(Z)-8-dodecen-1-ol,(Z)-9-dodecen-1-ol, et le (Z)-12-tetradecen-1-ol, se sont révélés en AEG comme des composés secondaires de la phéromone. L'étude par AEG de la relation dose-réponse a conduit à l'hypothèse de deux catégories de populations de récepteurs de phéromones. L'analyse comportementale des résponses des papillons mâles dans le tunnel de vol aux composés qui ont provoqués les plus forts AEG, on fait estimer que les acétates (E,E)-8,10-dodécadien-1-ol et (Z)-9-dodecen-1-ol ressemblent (ou sont) les constituants de la phéromone sexuelle de C. caryana; tandis que les (Z)-8-dodecen-1-ol et (E)-10-dodecen-1-ol sont, soit des paraphéromones, soit des constituants mineurs de la phéromone.La signification biologique du (Z)-12-tétradécen-1-ol a été difficile à interprêter avec les expériences en tunnel de vol.

     

Fine-scale resolution of closely spaced pheromone and antagonist filaments by flying male Helicoverpa zea

The limits of a male moth's ability to resolve closely spaced odor filaments have been investigated. Male Helicoverpa zea normally respond to their conspecific sex pheromone blend by exhibiting an upwind flight, which culminates in source contact by at least 50% of the bioassayed individuals. When loaded onto the same filter paper source containing this hitherto attractive pheromone blend, or onto a separate filter paper and co-emitted from the same pipette source with pheromone, (Z)-11-hexadecenyl acetate severely reduced upwind flight and source contact by male H. zea. A similar level of upwind flight inhibition was recorded when the antagonist (Z)-11-hexadecenyl acetate was emitted from its own point source placed 1 mm upwind of the pheromone point source, both plumes being simultaneously emitted in a continuous mode to form a confluent strand. However, (Z)-11-hexadecenyl acetate was less effective in reducing upwind flight and source contact when it was isolated and pulsed from its own source, placed 1 mm either upwind, downwind or cross-wind of a pipette source from which pheromone was simultaneously being pulsed, such that both filaments were separated in time by 0.001–0. 003 s. These results suggest that male H. zea are able to distinguish between odor sources separated by as little as 1 mm in space and 0.001 s in time. Accepted: 31 March 1999