Identification,Synthesis, and Field Tests of the Sex Pheromone of <Emphasis Type="Italic">Margarodes prieskaensis</Emphasis> (Jakubski)

Here, we report the identification and synthesis of the sex pheromone of female Margarodes prieskaensis (Jakubski), and the attractiveness of the synthetic pheromone to males in field trapping tests. Volatile organic compounds were collected from virgin females using a sample enrichment probe (SEP). Analyses by gas chromatography coupled to mass spectrometry revealed the presence of only two constituents. By scaling up the SEP, sufficient of the major constituent was collected for ¹H and ¹³C nuclear magnetic resonance (NMR) analyses and ancillary NMR techniques. The sex attractant was identified as (2R,4R,6R,8R)-2,4,6,8-tetramethylundecan-1-ol. The enantiomerically pure compound was synthesized from octadecyl (2R,4R,6R,8R)-2,4,6,8-tetramethylundecanoate, a minor component of the uropygial (preen) gland secretion of the domestic goose, Anser domesticus. Field trapping experiments, carried out in vineyards in the Northern Cape Province of South Africa, showed that the synthetic compound was as attractive to winged males of M. prieskaensis as virgin females. The second compound detected was identified as the corresponding acetate, but addition of this did not affect the attractiveness of the major component. We believe this to be the first identification of a sex attractant of the Margarodidae.     

Multiple Roles of a Male-Specific Compound in the Sexual Behavior of the Dried Bean Beetle, <Emphasis Type="Italic">Acanthoscelides Obtectus</Emphasis>

Males of Acanthoscelides obtectus (Coleoptera: Chrysomelidae, Bruchinae) emit methyl (E,R)-2,4,5-tetradecatrienoate that attracts females for mating. This study identified further roles for this compound in the sexual behavior of A. obtectus. Earlier observations revealed that males touched females with their antennae while tandem-running with them and initiated mounting and copulation, whereas they showed no such behavior toward other males. A series of subsequent laboratory choice tests were set up to establish if certain cuticular compounds aid contact sex recognition in A. obtectus. Males chose virgin females over other males. The activity toward females could be eliminated by rinsing with hexane, but was regained by application of female extract onto previously rinsed females. Gas chromatographic (GC) comparison of hexane extracts revealed the presence of two male-specific compounds, methyl (E,R)-2,4,5-tetradecatrienoate and octadecanal, which were absent from the behaviorally active female samples. Of the two compounds, methyl (E,R)-2,4,5-tetradecatrienoate was found to be responsible for the inhibition of male sexual behavior, similar to that observed with crude male extracts applied to virgin females. Furthermore, males preferred virgin over mated females. GC analyses revealed the presence of methyl (E,R)-2,4,5-tetradecatrienoate in mated females in amounts sufficient to curtail mating attempts. It appears that methyl (E,R)-2,4,5-tetradecatrienoate, besides being a male-produced sex pheromone, acts as a male-recognition signal in A. obtectus. Males also transfer it onto females during mating, resulting in mated females being avoided by courting males.     

Female Sex Pheromone in Trails of the Minute Pirate Bug, <Emphasis Type="Italic">Orius minutus</Emphasis> (L)

Orius minutus (L.) (Heteroptera: Anthocoridae) is a natural enemy of agricultural pests such as thrips, aphids, and various newly hatched insect juveniles. In this study, we conducted 1) behavioral assays for evidence of contact sex pheromone activity in trails of O. minutus, and 2) chemical analysis to identify the essential chemical components of the trails. Males showed arrestment to trails of mature virgin females but not to trails from either conspecific nymphs or immature females. Females also showed arrestment to trails from conspecific males, although the response was weaker than that exhibited by males. The activity of female trails lasted for at least 46 h after deposition. Males showed a response irrespective of mating experience. Following confirmation that a contact sex pheromone was present in the trails of female O. minutus, we used a bioassay-driven approach to isolate the active chemicals. After fractionation on silica gel, the n-hexane fraction was found to be biologically active to males. A major compound in the active fraction was (Z)-9-nonacosene; this compound was found only in trail extracts of mature virgin females. Synthetic (Z)-9-nonacosene arrested O. minutus males, indicating that it is the major active component of the contact sex pheromone in the trails of female O. minutus.     

Sexual Deception in the <Emphasis Type="Italic">Eucera</Emphasis>-Pollinated <Emphasis Type="Italic">Ophrys leochroma</Emphasis>: A Chemical Intermediate between Wasp- and <Emphasis Type="Italic">Andrena-</Emphasis>Pollinated Species

Ophrys flowers mimic sex pheromones of attractive females of their pollinators and attract males, which attempt to copulate with the flower and thereby pollinate it. Virgin females and orchid flowers are known to use the same chemical compounds in order to attract males. The composition of the sex pheromone and its floral analogue, however, vary between pollinator genera. Wasp-pollinated Ophrys species attract their pollinators by using polar hydroxy acids, whereas Andrena-pollinated species use a mixture of non-polar hydrocarbons. The phylogeny of Ophrys shows that its evolution was marked by episodes of rapid diversification coinciding with shifts to different pollinator groups: from wasps to Eucera and consequently to Andrena and other bees. To gain further insights, we studied pollinator attraction in O. leochroma in the context of intra- and inter-generic pollinator shifts, radiation, and diversification in the genus Ophrys. Our model species, O. leochroma, is pollinated by Eucera kullenbergi males and lies in the phylogeny between the wasp and Andrena-pollinated species; therefore, it is a remarkable point to understand pollinator shifts. We collected surface extracts of attractive E. kullenbergi females and labellum extracts of O. leochroma and analyzed them by using gas chromatography with electroantennographic detection (GC-EAD) and gas chromatography coupled with mass spectrometry (GC-MS). We also performed field bioassays. Our results show that O. leochroma mimics the sex pheromone of its pollinator’s female by using aldehydes, alcohols, fatty acids, and non-polar compounds (hydrocarbons). Therefore, in terms of the chemistry of pollinator attraction, Eucera-pollinated Ophrys species might represent an intermediate stage between wasp- and Andrena-pollinated orchid species.     

Sex Pheromone of the Cotton Mealybug, <Emphasis Type="Italic">Phenacoccus solenopsis</Emphasis>, with an Unusual Cyclobutane Structure

The cotton mealybug, Phenacoccus solenopsis, the distribution of which was formerly limited to Nearctic and Neotropical regions, recently invaded many countries in various regions including Asia, Africa, and the Pacific. More recently, P. solenopsis was newly recorded in Japan and is currently an emerging pest of agricultural crops. In this study, we determined the structure of a sex pheromone of P. solenopsis in order to develop an effective lure for monitoring this pest. From volatiles emitted by virgin adult females, we isolated a compound attractive to males. By means of coupled gas chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy, we identified this as (2,2-dimethyl-3-isopropylidenecyclobutyl)methyl 3-methylbut-2-enoate. This compound was synthesized and shown to be attractive to male P. solenopsis. Analysis by gas chromatography using an enantioselective stationary phase and polarimetry analyses of the natural pheromone and synthetic enantiomers showed the natural compound to be the (R)-(?)-enantiomer. This compound is an ester of maconelliol, which has an unusual cyclobutane structure found in sex pheromones of other mealybug species, and senecioic acid, also found in the pheromones of other mealybug species. However, this is the first example of the ester of maconelliol and senecioic acid as a natural product.     

Identification of a Sex Attractant Pheromone for Male Winterform Pear Psylla, <Emphasis Type="Italic">Cacopsylla pyricola</Emphasis>

Pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), a major economic pest of pears, uses a female-produced sex attractant pheromone. We compared the chemical profiles obtained from cuticular extracts of diapausing and post-diapause winterform males and females to isolate and identify the pheromone. Post-diapause females produced significantly more of the cuticular hydrocarbon, 13-methylheptacosane, than post-diapause males and diapausing females. In olfactometer assays, conspecific males were attracted to synthetic racemic 13-methylheptacosane, whereas females were not, indicating that the behavioral response to this chemical is sex-specific. Furthermore, 13-methylheptacosane was as attractive to males as a cuticular extract of females, suggesting that this chemical was largely responsible for the female attractiveness. A field study showed that males but not females were attracted to 13-methylheptacosane, confirming the olfactometer results. This study provides evidence that 13-methylheptacosane is a sex attractant pheromone for C. pyricola winterform males. This is the first identification of a sex pheromone in the Psylloidea. Our results open the path to developing monitoring tools and possibly new strategies for integrated pest management of this insect.     

Interspecific Cross-Attraction between the South American Cerambycid Beetles <Emphasis Type="Italic">Cotyclytus curvatus</Emphasis> and <Emphasis Type="Italic">Megacyllene acuta</Emphasis> is Averted by Minor Pheromone Components

During field screening trials conducted in Brazil in 2015, adults of both sexes of the cerambycid beetles Cotyclytus curvatus (Germar) and Megacyllene acuta (Germar) (subfamily Cerambycinae, tribe Clytini) were significantly attracted to racemic 3-hydroxyhexan-2-one and racemic 2-methylbutan-1-ol, chemicals which previously have been identified as male-produced aggregation-sex pheromones of a number of cerambycid species endemic to other continents. Subsequent analyses of samples of beetle-produced volatiles revealed that males of C. curvatus sex-specifically produce only (R)-3-hydroxyhexan-2-one, whereas males of M. acuta produce the same compound along with lesser amounts of (2S,3S)-2,3-hexanediol and (S)-2-methylbutan-1-ol. Follow-up field trials showed that both sexes of both species were attracted to synthetic reconstructions of their respective pheromones, confirming that males produce aggregation-sex pheromones. The minor pheromone components of M. acuta, (S)-2-methylbutan-1-ol and (2S,3S)-2,3-hexanediol, synergized attraction of that species, but antagonized attraction of C. curvatus to (R)-3-hydroxyhexan-2-one. Beetles of other cerambycine species also were attracted in significant numbers, including Chrysoprasis linearis Bates, Cotyclytus dorsalis (Laporte & Gory), and Megacyllene falsa (Chevrolat). Our results provide further evidence that 3-hydroxyhexan-2-one is a major component of attractant pheromones of numerous cerambycine species world-wide. Our results also highlight our increasing understanding of the crucial role of minor pheromone components in imparting species specificity to cerambycid pheromone blends, as is known to occur in numerous species in other insect families.     

Pheromonal Cues Deposited by Mated Females Convey Social Information about Egg-Laying Sites in <Emphasis Type="Italic">Drosophila Melanogaster</Emphasis>

Individuals can make choices based on information learned from others, a phenomenon called social learning. How observers differentiate between which individual they should or should not learn from is, however, poorly understood. Here, we showed that Drosophila melanogaster females can influence the choice of egg-laying site of other females through pheromonal marking. Mated females mark territories of high quality food by ejecting surplus male sperm containing the aggregation pheromone cis-11-vaccenyl acetate (cVA) and, in addition, deposit several sex- and species-specific cuticular hydrocarbon (CHC) pheromones. These pheromonal cues affect the choices of other females, which respond by preferentially laying eggs on the marked food. This system benefits both senders and responders, as communal egg laying increases offspring survival. Virgin females, however, do not elicit a change in the egg-laying decision of mated females, even when food has been supplemented with ejected sperm from mated females, thus indicating the necessity for additional cues. Genetic ablation of either a female’s CHC pheromones or those of their mate results in loss of ability of mated females to attract other females. We conclude that mated females use a pheromonal marking system, comprising cVA acquired from male ejaculate with sex- and species-specific CHCs produced by both mates, to indicate egg-laying sites. This system ensures information reliability because mated, but not virgin, females have both the ability to generate the pheromone blend that attracts other flies to those sites and a direct interest in egg-laying site quality.     

Male Pheromones Influence the Mating Behavior of <Emphasis Type="Italic">Echinothrips americanus</Emphasis>

Two dibasic esters, the dimethyl ester of hexanedioic acid (dimethyl adipate, DBE-6) and the dimethyl ester of pentanedioic acid (dimethyl glutarate, DBE-5) were found in head-thorax extracts of male Echinothrips americanus. DBE-5 induced abdomen wagging and raising in males and females, which is typically exhibited when encountering a male. DBE-6 was avoided by males and was detected on mated, but not on virgin, females. Both substances applied to virgin females lead to females being ignored by males. The role of both substances is discussed with regard to the male mating system.     

Identification of Sex Pheromones and Sex Pheromone Mimics for Two North American Click Beetle Species (Coleoptera: Elateridae) in the Genus <Emphasis Type="Italic">Cardiophorus</Emphasis> Esch.

To date, all known or suspected pheromones of click beetles (Coleoptera: Elateridae) have been identified solely from species native to Europe and Asia; reports of identifications from North American species dating from the 1970s have since proven to be incorrect. While conducting bioassays of pheromones of a longhorned beetle (Coleoptera: Cerambycidae), we serendipitously discovered that males of Cardiophorus tenebrosus L. and Cardiophorus edwardsi Horn were specifically attracted to the cerambycid pheromone fuscumol acetate, (E)-6,10-dimethylundeca-5,9-dien-2-yl acetate, suggesting that this compound might also be a sex pheromone for the two Cardiophorus species. Further field bioassays and electrophysiological assays with the enantiomers of fuscumol acetate determined that males were specifically attracted by the (R)-enantiomer. However, subsequent analyses of extracts of volatiles from female C. tenebrosus and C. edwardsi showed that the females actually produced a different compound, which was identified as (3R,6E)-3,7,11-trimethyl-6,10-dodecadienoic acid methyl ester (methyl (3R,6E)-2,3-dihydrofarnesoate). In field trials, both the racemate and the (R)-enantiomer of the pheromone attracted similar numbers of male beetles, suggesting that the (S)-enantiomer was not interfering with responses to the insect-produced (R)-enantiomer. This report constitutes the first conclusive identification of sex pheromones for any North American click beetle species. Possible reasons for the strong and specific attraction of males to fuscumol acetate, which is markedly different in structure to the actual pheromone, are discussed.     

Chemical Characterization of Young Virgin Queens and Mated Egg-Laying Queens in the Ant <Emphasis Type="Italic">Cataglyphis cursor</Emphasis>: Random Forest Classification Analysis for Multivariate Datasets

Social insects are well known for their extremely rich chemical communication, yet their sex pheromones remain poorly studied. In the thermophilic and thelytokous ant, Cataglyphis cursor, we analyzed the cuticular hydrocarbon profiles and Dufour’s gland contents of queens of different age and reproductive status (sexually immature gynes, sexually mature gynes, mated and egg-laying queens) and of workers. Random forest classification analyses showed that the four groups of individuals were well separated for both chemical sources, except mature gynes that clustered with queens for cuticular hydrocarbons and with immature gynes for Dufour’s gland secretions. Analyses carried out with two groups of females only allowed identification of candidate chemicals for queen signal and for sexual attractant. In particular, gynes produced more undecane in the Dufour’s gland. This chemical is both the sex pheromone and the alarm pheromone of the ant Formica lugubris. It may therefore act as sex pheromone in C. cursor, and/or be involved in the restoration of monogyny that occurs rapidly following colony fission. Indeed, new colonies often start with several gynes and all but one are rapidly culled by workers, and this process likely involves chemical signals between gynes and workers. These findings open novel opportunities for experimental studies of inclusive mate choice and queen choice in C. cursor.     

Effect of Male House Mouse Pheromone Components on Behavioral Responses of Mice in Laboratory and Field Experiments

Urine of male house mice, Mus musculus, is known to have primer pheromone effects on the reproductive physiology of female mice. Urine-mediated releaser pheromone effects that trigger certain behavioral responses are much less understood, and no field studies have investigated whether urine deposits by male or female mice, or synthetic mouse pheromone, increase trap captures of mice. In field experiments, we baited traps with bedding soiled with urine and feces of caged female or male mice, and recorded captures of mice in these and in control traps containing clean bedding. Traps baited with female bedding preferentially captured adult males, whereas traps baited with male bedding preferentially captured juvenile and adult females, indicating the presence of male- and female-specific sex pheromones in soiled bedding. Analyses of headspace volatiles emanating from soiled bedding by gas chromatography/mass spectrometry revealed that 3,4-dehydro-exo-brevicomin (DEB) was seven times more prevalent in male bedding and that 2-sec-butyl-4,5-dihydrothiazole (DHT) was male-specific. In a follow-up field experiment, traps baited with DEB and DHT captured 4 times more female mice than corresponding control traps, thus indicating that DEB and DHT are sex attractant pheromone components of house mouse males. Our study provides impetus to identify the sex attractant pheromone of female mice, and to develop synthetic mouse pheromone as a lure to enhance the efficacy of trapping programs for mouse control.     

<Emphasis Type="Italic">n</Emphasis>-Pentacosane Acts as both Contact and Volatile Pheromone in the tea Weevil, <Emphasis Type="Italic">Myllocerinus aurolineatus</Emphasis>

Insect cuticular hydrocarbons (CHCs) play important roles in chemical communication, as well as having ecological and physiological roles. The use of CHCs for mate recognition has been shown in many insect genera, but little is known about their use in the tea weevil Myllocerinus aurolineatus. Here, we provide evidence that CHCs on the surface of sexually mature M. aurolineatus females act as contact sex pheromones, facilitating mate recognition and eliciting copulatory behavior in male weevils. Using gas chromatography-mass spectrometry, we identify n-pentacosane and n-heptacosane as two potential contact pheromone components. Results from arena bioassays showed that n-pentacosane is a component of a contact pheromone of M. aurolineatus. Further results from the Y-tube olfactometer bioassays showed that n-pentacosane also acts as a volatile attractant. Our results greatly improve our understanding of the chemical ecology of M. aurolineatus.     

Stingless Bees: Chemical Differences and Potential Functions in <Emphasis Type="Italic">Nannotrigona testaceicornis</Emphasis> and <Emphasis Type="Italic">Plebeia droryana</Emphasis> Males and Workers

Cuticular wax, abdominal and cephalic extracts of foraging workers and males of Nannotrigona testaceicornis and Plebeia droryana, from the “Aretuzina” farm in São Simão, SP, Brazil, were analyzed by GC-MS. The principal constituents were hydrocarbons, terpenes, aldehydes, esters, steroids, alcohols, and fatty acids. Interspecific differences for both cuticular wax and cephalic extracts were found. The composition of cuticular wax and cephalic extracts was similar at the intraspecific level, with minor component differences between males and workers. Abdominal extracts differentiated sexes (male and worker) at the intraspecific and interspecific levels. The main chemical components in abdominal extracts of N. testaceicornis workers and males were geranylgeranyl acetate and (Z)-9-nonacosene, respectively. The principal components of abdominal extracts from P. droryana workers and males were tetradecanal and unsaturated fatty acids (linoleic and linolenic acids), respectively. A secondary alcohol, (S)-2-nonanol, was detected in Plebeia droryana males only, but not in workers. Preliminary field experiments showed that (S)-(+)-2-heptanol and (S)-(+)-2-heptanol/ (S)-(+)-2-nonanol (1:1) attracted workers of P. droryana, N. testaceicornis, and Frieseomelitta silvestrii. However, males did not respond suggesting that these compounds do not function as alarm or recruitment pheromones . In addition, racemic mixtures were inactive.     

Sex Attractant Pheromones of Virgin Queens of Sympatric Slave-Making Ant Species in the Genus <Emphasis Type="Italic">Polyergus,</Emphasis> and their Possible Roles in Reproductive Isolation

Species of the ant genus Polyergus are social parasites that steal brood from colonies of their hosts in the closely related genus Formica. Upon emergence as adults in a mixed population, host Formica workers carry out all the normal worker functions within the Polyergus colony, including foraging, feeding, grooming, and rearing brood of the parasitic Polyergus ants. Some unmated Polyergus gynes (queens) run in the raiding columns of their colonies and attract males by releasing a pheromone from their mandibular glands. There are two Polyergus species groups in North America: an eastern P. lucidus group and a western P. breviceps group. One species of each of these groups, P. lucidus Mayr and P. mexicanus Emery, are sympatric in Missouri. In this study, we characterized the sex pheromones of virgin queens of two species of the P. lucidus group (P. lucidus sensu stricto and P. sanwaldi) and one species of the P. breviceps group (P. mexicanus), and compared these with the previously identified sex pheromone of P. topoffi of the P. breviceps group. We then used sex pheromone blends reconstructed from synthesized components of the two groups to test their efficacy at reproductively isolating these species. We found that methyl 6-methylsalicylate is conserved as the major component of the pheromone blends for both Polyergus species groups; however, methyl (R)-3-ethyl-4-methylpentanoate is the species-specific minor component produced by P. lucidus group queens, and (R)-3-ethyl-4-methylpentan-1-ol is the crucial minor component for P. breviceps group queens. The optimal ratio of the major and minor components for P. lucidus group queens was about 100:1 salicylate to ester. In concurrent field trials in Missouri, males of P. lucidus sensu stricto and P. mexicanus (a member of the P. breviceps group) were attracted almost exclusively to their particular blends of sex pheromone components. To our knowledge, this is the first example of a possible sex-pheromone-based reproductive isolating mechanism in ants.     

Identification of the Unsaturated Heptadecyl Fatty Acids in the Seed Oils of <Emphasis Type="Italic">Thespesia populnea</Emphasis> and <Emphasis Type="Italic">Gossypium hirsutum</Emphasis>

The fatty acid composition of the seed oils of Thespesia populnea and cotton variety SG-747 (Gossypium hirsutum) were studied to identity their 17-carbon fatty acids. With a combination of chemical derivatization, gas chromatography, and mass spectrometry, 8-heptadecenoic acid, 9-heptadecenoic acid, and 8,11-heptadecadienoic acids were identified in both oils. Additionally, traces of 10-heptadecenoic acid were identified in the T. populnea oil. Although these odd-carbon number fatty acids are present in only minor amounts in cottonseed oil, they make up about ~2 % of the fatty acids in T. populnea seed oil. The identification of these acids indicates that fatty acid α-oxidation is not restricted to cyclopropene fatty acids in these plants, but also occurs with unsaturated fatty acids. Combined with malvalic acid (generally accepted as being formed by α-oxidation of sterculic acid), ~7 % of the fatty acids in T. populnea seed have under gone α-oxidization. The results should help clarify the composition of T. populnea seed oil, which has been reported inconsistently in the literature.     

(1<Emphasis Type="Italic">S</Emphasis>,3<Emphasis Type="Italic">R</Emphasis>)-<Emphasis Type="Italic">cis</Emphasis>-Chrysanthemyl Tiglate: Sex Pheromone of the Striped Mealybug, <Emphasis Type="Italic">Ferrisia virgata</Emphasis>

Derivatives of 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylic acid (chrysanthemic acid) are classic natural pyrethroids discovered in pyrethrum plants and show insecticidal activity. Chrysanthemic acid, with two asymmetric carbons, has four possible stereoisomers, and most natural pyrethroids have the (1R,3R)-trans configuration. Interestingly, chrysanthemic acid–related structures are also found in insect sex pheromones; carboxylic esters of (1R,3R)-trans-(2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl)methanol (chrysanthemyl alcohol) have been reported from two mealybug species. In the present study, another ester of chrysanthemyl alcohol was discovered from the striped mealybug, Ferrisia virgata (Cockerell), as its pheromone. By means of gas chromatography–mass spectrometry, nuclear magnetic resonance spectrometry, and high-performance liquid chromatography analyses using a chiral stationary phase column and authentic standards, the pheromone was identified as (1S,3R)-(?)-cis-chrysanthemyl tiglate. The (1S,3R)-enantiomer strongly attracted adult males in a greenhouse trapping bioassay, whereas the other enantiomers showed only weak activity. The cis configuration of the chrysanthemic acid–related structure appears to be relatively scarce in nature, and this is the first example reported from arthropods.     

Volatile and Contact Chemical Cues Associated with Host and Mate Recognition Behavior of <Emphasis Type="Italic">Sphenophorus venatus</Emphasis> and <Emphasis Type="Italic">Sphenophorus parvulus</Emphasis> (Coleoptera: Dryophthoridae)

Beetles in the genus Sphenophorus Schönherr, or billbugs, potentially utilize both volatile and non-volatile behavior-modifying chemical signals. These insects are widely distributed across North America, often occurring in multi-species assemblages in grasses. However, details about their host- and mate-finding behavior are poorly understood. This study tested the hypothesis that volatile organic compounds from host-plants and conspecifics direct the dispersal behavior of hunting billbug S. venatus Say. Further, we characterized the cuticular hydrocarbon profiles of two widespread pest species, S. venatus and bluegrass billbug S. parvulus Gyllenhaal, to assess the potential role of contact pheromones in mate-recognition. In Y-tube olfactometer bioassays, S. venatus males were attracted to a combination of conspecifics and Cynodon dactylon host-plant material, as well as C. dactylon plant material alone. S. venatus females were attracted to a combination of male conspecifics and host-plants but were also attracted to male conspecifics alone. Field evaluation of a putative male-produced aggregation pheromone, 2-methyl-4-octanol, identified from two congeners, S. levis Vaurie and S. incurrens Gyllenhaal, did not support the hypothesis that S. venatus and S. parvulus were also attracted to this compound. Gas chromatography-mass spectrometry analysis of S. venatus and S. parvulus whole-body cuticular extracts indicated a series of hydrocarbons with qualitative and quantitative interspecific variation in addition to intraspecific quantitative variation between males and females. This study provides the first evidence that S. venatus orients toward host- and insect-derived volatile organic compounds and substantiates the presence of species-specific cuticular hydrocarbons that could serve as contact pheromones for sympatric Sphenophorus species.     

Sex Attractant Pheromone of the Luna Moth, <Emphasis Type="Italic">Actias luna</Emphasis> (Linnaeus)

Giant silk moths (Lepidoptera: Saturniidae) typically are not well represented as larvae or adults in community level inventories of Lepidoptera, and as a result, little is known about their population dynamics. Furthermore, in recent years, many species of silk moths appear to have experienced population declines. Volatile sex pheromones are powerful sampling tools that can be used in operational conservation and monitoring programs for insects. Here, we describe the identification of the sex attractant pheromone of a giant silk moth, the luna moth Actias luna. Coupled gas chromatography-electroantennographic detection and gas chromatography-mass spectrometric analyses of extracts from pheromone glands of female luna moths supported the identification of (6E,11Z)-6,11-octadecadienal (E6,Z11–18:Ald), (6E)-6-octadecenal (E6–18:Ald), and (11Z)-11-octadecenal (Z11–18:Ald) as the compounds in extracts that elicited responses from antennae of male moths. These identifications were confirmed by synthesis, followed by testing of blends of the synthetic compounds in field trials in Ontario, Canada, and Kentucky, USA. Male moths were attracted to synthetic E6,Z11–18:Ald as a single component. Attraction appeared to be enhanced by addition of E6–18:Ald but not Z11–18:Ald, suggesting that the luna moth pheromone consists of a blend of E6,Z11–18:Ald and E6–18:Ald.