Identification of Sex Pheromone Components of the Box Tree Pyralid,Glyphodes perspectalis

Analysis of ovipositor extracts of the box tree pyralid, Glyphodes perspectalis (Lepidoptera: Crambidae), by coupled gas chromatography-electroantennogram detection and gas chromatography yielded three candidate pheromone compounds. Gas chromatography-mass spectrometry, and reaction with dimethyl disulfide (DMDS), identified these compounds as (Z)-11-hexadecenal (Z11-16:Ald), (E)-11-hexadecenal (E11-16:Ald), and (Z)-11-hexadecenol (Z11-16:OH). The ratio of these three compounds in crude extract was 5:1.25:1, and the total amount was approximately 100 ng/female. In laboratory bioassays, Z11-16:Ald alone was attractive to males. In field bioassays, however, Z11-16:Ald alone was not attractive to males, but a mixture of Z11-16:Ald and E11-16:Ald was. The addition of Z11-16:OH to the two aldehydes, significantly reduced attractiveness to male moths in a field trial. From these results, we conclude that the aldehyde compounds comprise the sex pheromone components of G. perspectalis. A rubber septum containing 0.6 mg of the two aldehydes at the natural ratio was an effective lure for monitoring this pest.     

Sex pheromone of fall armyworm,Spodoptera frugiperda (J.E. Smith)

Analyses of extracts of pheromone glands and of volatiles from calling female fall armyworm moths,Spodoptera frugiperda (J.E. Smith), revealed the presence of the following compounds: dodecan-1-ol acetate, (Z)-7-dodecen-1-ol acetate, 11-dodecen-1-ol acetate, (Z)-9-tetradecenal, (Z)-9-tetradecen-1-ol acetate, (Z)-11-hexadecenal, and (Z)-11-hexadecen-1-ol acetate. The volatiles emitted by calling females differed from the gland extract in that the two aldehydes were absent. Field tests were conducted with sticky traps baited with rubber septa formulated to release blends with the same component ratios as those emitted by calling females. These tests demonstrated that both (Z)-7-dodecen-1-ol acetate and (Z)-9-tetradecen-1-ol acetate are required for optimum activity and that this blend is a significantly better lure than either virgin females or 25 mg of (Z)-9-dodecen-1-ol acetate in a polyethylene vial, the previously used standard. Addition of the other three acetates found in the volatiles did not significantly increase the effectiveness of the two-component blend as a bait for Pherocon 1C or International Pheromones moth traps.Mention of a commercial or proprietary product does not constitute an endorsement by the USDA.     

Roles of minor components in pheromone-mediated behavior of western spruce budworm male moths

The behavior of male western spruce budworm moths,Choristoneura occidentalis Freeman, was observed in a flight tunnel in response to virgin females and synthetic sex pheromone components, alone and in blends. Pheromone blends were also compared in the field using sticky trap bioassays. Pheromones were incorporated into small rods of polyvinyl chloride. The blend of 928 (E/Z)-11-tetradecenal-8911 (E/Z)-11-tetradecenyl acetate-8515 (E/Z)-11-tetradecenol (AldAcOH) that approximated that released from a virgin female moth elicited levels of response similar to those elicited by the female. This blend induced a significantly greater percentage of moths to fly upwind and land at the lure than did the Ald lure. In contrast to the flight-tunnel bioassays, the numbers of moths caught in Ald-baited sticky traps in the field were not significantly increased by the addition of Ac and OH lures. The net upwind groundspeed of flight in response to the 0.05% Ald lure was lower than that in response to the virgin females and was significantly increased by the addition of Ac + OH lures in two of three bioassays. The flight-tunnel bioassays support the hypothesis that the natural blend of major (Ald) and minor (Ac + OH) components stimulates the precopulatory behavior of western spruce budworm male moths at long range (> 1 m downwind) as well as at close range.     

Sex Pheromone of <Emphasis Type="BoldItalic">Lonomia obliqua</Emphasis>: Daily Rhythm of Production,Identification, and Synthesis

The sex pheromone of Lonomia obliqua Walker (Lepidoptera: Saturniidae) was studied in the laboratory. All female calling occurred during the scotophase. Most females (70.6%) called first within 24 hr of eclosion. Calling varied with age of female, with older (5- to 6-day-old) females calling earlier in the scotophase and for longer durations than younger (0- to 1-day-old) females. The sex pheromone gland of 1- to 3-day-old virgin females was extracted during the calling peak. A Y-olfactometer bioassay showed significant attraction of males to a filter paper containing the female gland extract. Gas chromatographic-electroantennogram detection (GC-EAD) analysis of the extract indicated the presence of at least two possible pheromone components. Gas chromatographic-mass spectrometric analysis of the major GC-EAD-active peak indicated a hexadecenyl acetate; chemical derivatization indicated Δ11 unsaturation. Synthetic samples of (E)- and (Z)-11-hexadecenyl acetate were obtained by coupling 10-bromo-1-decanol and 1-hexyne, utilizing lithium chemistry. The comparison of the retention time of dimethyl disulfide derivatives of the natural compound, to those of synthetic chemicals, confirmed the natural compound as (E)-11-hexadecenyl acetate. The minor component was identified as the related alcohol, (E)-11-hexadecenol. The ratio of the two components in female extract was 100:35. Preliminary tests of males in a Y-olfactometer showed that their response to a mixture of the two compounds was not significantly different from that to gland extract.     

Sex pheromone of blackheaded fireworm,Rhopobota naevana (Lepidoptera: Tortricidae), a pest of cranberry

Splitless capillary gas chromatography indicated the presence of (Z)- and (E)-11-tetradecenyl acetate and (Z)-11-tetradecenyl alcohol in the washes of female abdominal tips of the blackheaded fireworm,Rhopobota naevana (Hubner). Gas chromatography combined with mass spectroscopy confirmed the presence of tetradecenyl acetate in extracts of female tips. The low levels observed in these extracts (< 1 ng/female equivalent), prevented further chemical and spectroscopic identification. These materials were found to be stimulatory at low levels in electroantennogram studies. A combination of 9 g of (Z)-11-tetradecenyl acetate and 3 g of (Z)-11-tetradecenyl alcohol on rubber septa in wing traps provided an effective attractant. (Z)-9-Dodecenyl acetate, a previously reported attractant, did not significantly increase field trapping catches when added to the binary mixture, but was found to enhance trap catches when added to each of the primary components.     

Oviposition attractants and repellents of mosquitoes

Infusions of various organic materials have been known to modify ovipositional behavior of gravid female mosquitoes. Previously, we found that an infusion of Purina Laboratory Chow elicited negative ovipositional behavior inCulex pipiens quinquefasciatus Say andCulex tarsalis Coquillett. In the present chemical studies, the Purina Laboratory Chow infusion, fermented for 10 days, was distilled to give an active distillate which, upon ether extraction, gave an active ether extract. Fractionation of the ether extract yielded an active acidic fraction and inactive nonacidic fraction. Gas Chromatographie analysis on Porapak R and AT-1200-H₃PO₄ columns of the acidic fraction showed the presence of acetic, propionic, isobutyric, butyric, isovaleric, and caproic acids. In bioassay tests, these lower aliphatic carboxylic acids, individually and in combination, exhibited ovipositional repellency against the two species of mosquitoes at the concentration of 6 × 10^–2%. At this concentration, butyric acid caused 100% mortality in first-instar larvae ofC. p. quinquefasciatus. Gravid female mosquitoes might have acquired, through evolutional adaptation, the ability of avoiding ovipositing in unsuitable sites in which toxic compounds might be detrimental to the survival and development of their offspring.Diptera: Culicidae.     

Sex Pheromones of Thysanoplusia intermixta and T. orichalcea: Identification and Field Tests

Thysanoplusia intermixta, which inhabits the temperate zone in Japan, is a defoliator of plants in the family Compositae, Apiaceae, and others. By GC-MS analysis, (Z)-7-dodecenyl acetate, (Z)-7-dodecen-l-ol, (5E, 7Z)-5,7-dodecadienyl acetate and (5E, 7Z)-5,7-dodecadien-l-ol were identified from a pheromone gland extract of the virgin females in a ratio of 18:3:100:13. A lure baited only with the major diene acetate could attract male moths of T. intermixta in the field. Other minor components had a synergistic effect on the attraction of the diene acetate. The same four components were included in a very different ratio of 100:6:11:1 in the gland extract of Thysanoplusia orichalcea, a closely related subtropical species. The monoene and diene acetates are essential for field attraction, and a 100:11 mixture is an optimum lure for T. orichalcea males. However, this mixture, including the diene acetate as a minor component, captured very few T. intermixta males, suggesting the possibility that these two Thysanoplusia species are reproductively isolated from each other by pheromonal communication.     

Sex pheromone of the avocado pest,Amorbia cuneana (Walsingham) (Lepidoptera: Tortricidae)

The major volatile components in the extract of the female sex pheromone gland ofAmorbia cuneana consisted of (E,E)- and (E,Z)-10,12-tetradecadien-1-ol acetates. The identification was based on electroantennogram bioassay of gas Chromatographic effluent from sex pheromone gland extract, relative retention times on polar and nonpolar gas chromatographic columns, chemical degradation (ozonolysis, saponification), mass spectrometry, chemical synthetic methods, and field tests. Based on mass spectrometry and retention times by capillary gas chromatography, traces of (E)-10-tetradecen-1-ol acetate and 1-tetradecanol acetate were also present in the extract. Traps baited with a combination of synthetic (E,E)- and (E,Z)-10,12-tetradecadien-1-ol acetates caught more males than did traps baited with females.This paper reports the results of research only. Mention of a commercial product in this paper does not constitute a recommendation by the U.S. Department of Agriculture.     

Chemical fractionation of shrimp extracts inducing bottom food search behavior in cod (Gadus morhua L.)

The bottom food search (BFS) feeding behavior in cod (Gadus morhua L.), has been used in a bioassay for chemical isolation of the feeding stimulant substances present in shrimp (Pandalus borealis). An aqueous methanol extract of ground shrimp was separated into acidic, neutral, and amphoteric/basic fractions by ion-exchange chromatography and into single components by preparative high-pressure liquid chromatography (HPLC). Of the isolated single components, the amino acid glycine was most potent, followed by alanine. Two unidentified substances were also highly potent. There was a synergistic effect between glycine, alanine, proline, and arginine. These four amino acids were more potent than the total amino acid pool found in the shrimp extract, indicating that there may be amino acids in this pool having an antagonistic effect.     

Chemistry of the Cephalic Labial Gland Secretions of Male Bombus morrisoni and B. rufocinctus, Two North American Bumblebee Males with Perching Behavior

The labial gland secretions from males of the North American bumblebees Bombus morrisoni Cresson and B. rufocinctus Cresson were analyzed by gas chromatography/mass spectrometry. In both species, 3,7,11,15-tetramethyl-2,6,10,14-hexadecatetraenyl acetate was found as the major compound of a complex mixture of alkenols, acetates, hydrocarbons, and wax-type esters. In addition to a mixture of saturated and mono-unsaturated straight chain hydrocarbons, the labial gland of both species contained the isoprenoid hydrocarbons (6E, 10E)-3,7,15-trimethyl-3-methylene-hexadeca-1,6,10,14-tetraene [β-springene], three isomers of 3,7,11,15-tetramethyl-hexadeca-1,3,6,10,14-pentaene [α-springene], and two further unidentified cyclic diterpenes. In B. morrisoni, 3,7,11-trimethyl-2,6,10-dodecatrien-1-ol and 3,7,11,15-tetramethyl-6,10,14-hexadecatrien-1-ol were detected as characteristic alcohols, as well as small amounts of 9-hexadecenol and hexadecanol. Furthermore, a large peak of hexadecyl dodecanoate and minor amounts of 9-hexadecenyl, 9-octadecenyl, and eicosenyl 9-tetradecenoate were found as typical esters in this species. In B. rufocinctus, 9-hexadecenol, hexadecanol, and 9-octadecenol were present in considerable amounts, with their acetates and 9-tetradecenoic, tetradecanoic, hexadecanoic, and 11-octadecenoic acids. The chemical composition of cephalic labial glands in male bumblebees with perching behavior is discussed.     

Sexual communication and associative learning in the parasitic waspItoplectis conquisitor (Say)

Extracts of newly emerged virgin females and newly emerged virgin males of the parasitic waspItoplectis conquisitor were highly active in eliciting sexual behavior in older males. Newly emerged males did not respond to the extracts. A reliable biological assay was devised in which the responses of males to extract could be evaluated under varying conditions. Optimum male responses to female extract were obtained at 27 °C and at 1.0 female equivalents (the amount of pheromone extractable from the body surface of a female). A decrease in sexual response was observed when males were repeatedly exposed to pheromone. Males also learned to associate bioassay conditions with the presence of pheromone.     

Role of plant odor in parasitism of European corn borer by braconid specialist parasitoidMacrocentrus grandii Goidanich: Isolation and characterization of plant synomones eliciting parasitoid flight response

In an earlier study we documented attraction of the specialist parasitoidMacrocentrus grandii Goidanich to odors of com, potato, and snap bean. In the present study the chemical bases of the parasitoid’s attraction to these food plants of its European corn borer host were compared. Volatile compounds from corn leaves were isolated using Tenax and identified by capillary gas chromatographic-mass spectrometry. Twenty-one compounds including aldehydes, ketones, alcohols, esters, and sesquiterpenes were present in corn. These were separated into fractions by column chromatography on Florisil. Wind-tunnel bioassays of the fractions indicated thatM. grandii was attracted to fractions containing nonpolar and slightly polar compounds including sesquiterpenes, aldehydes, a ketone, and esters. More polar compounds in corn, like alcohols, were not attractive. Attraction to potato odor was based on the presence of the same classes of compounds that were attractive in corn, but more polar compounds were involved in attraction to snap bean odor. This study indicated that only some compounds in each of the three odor complexes tested were attractive. It also documented that different compounds were involved in attraction ofM. grandii to different plant odors.     

Differences among sibling speciesRhagoletis mendax andR. pomonella (diptera: ephritidae) in their antennal sensitivity to host fruit compounds

Prior electrophoretic and morphological studies have identified two closely related, economically important tephritid flies,R. mendax (Curran) andR. pomonella (Walsh), which infest the fruits of ericaceous and rosaceous plants, respectively. Further studies also have shown consistent differences among these species in their ovipositional preferences for apples and highbush blueberries and have determined that their ovipositional behavior is elicited by extracts obtained from these fruits. In this paper we report the results of an experiment that tested whether these species show distinct electroantennogram (EAG) responses to a large array of compounds present in gas chromatograph-fractionated pentane extracts of apples and highbush blueberries.R. mendax andR. pomonella flies were found to have significant differences in their antennal sensitivity to 11 blueberry and nine apple extract peaks, which correspond to 24.4% of all blueberry and 25.0% of all apple peaks that elicited a measurable EAG response from either species. Interspecific differences in peripheral sensitivity were more pronounced for blueberry than apple extract;R. pomonella flies were most sensitive to blueberry compounds with low retention times, whereasR. mendax flies responded to blueberry compounds with a broader range of retention times. Both species were most sensitive to apple peaks with high retention times. The retention times of most apple and blueberry peaks that elicited EAG responses fromR. mendax andR. pomonella flies were different from the retention times of seven attractant fruit esters that were previously identified by Fein et al. (1982). The identification of these unknown apple and blueberry compounds could lead to the discovery of new chemical cues that mediate the host-plant preferences of these sibling species.     

Sex Pheromone of the Citrus Flower Moth <Emphasis Type="Italic">Prays nephelomima</Emphasis>: Pheromone Identification,Field Trapping Trials,and Phenology

Analysis of sex pheromone gland extract of the citrus flower moth, Prays nephelomima (Lepidoptera: Yponomeutidae) by coupled gas chromatography–electroantennogram detection, revealed one electrophysiologically active compound. Structural analysis using gas chromatography, gas chromatography–mass spectrometry, and dimethyldisulfide derivatization identified this as the monounsaturated aldehyde (Z)-7-tetradecenal. Field trials in commercial citrus orchards on the North Island of New Zealand showed that (Z)-7-tetradecenal was highly attractive to male P. nephelomima. Phenology data, collected over 19 months in three commercial orchards, from traps baited with the sex pheromone at a lure loading of 300 μg on a red rubber septum, indicated that male moths may be present throughout the year, with numbers peaking in late summer and autumn.     

Female sex pheromone-mediated effects on behavior and consequences of male competition in the shore crab (Carcinus maenas)

Exposure to receptive female pheromone elicits guarding behavior in shore crab males (Carcinus maenas), but little is known about the effects of sex pheromone on male competition or if the female plays an active role in mate choice. This study examined whether female pheromone enhanced agonistic behavior between males and what effects visual and chemical cues had on the rules and costs of such contests. We also investigated whether females exhibit a preference for males in terms of size. Under laboratory conditions, solitary male shore crabs engaged males who already had possession of a female. The visual and chemical presence of a receptive female had an impact on contest rules and costs. Fights were costly in terms of duration and of sustaining injury with either one or both crabs incurring injury in 40% of fights. To investigate the metabolic consequences of fighting over a perceived sexual resource (chemical cue only), fights were staged between pairs of size-matched males in the presence of water containing the female sex pheromone, water in which males had been kept, and untreated seawater. The duration and intensity of contests were greater when staged in the presence of the female pheromone compared with the two other treatments. Crabs that fought in the presence of female sex pheromone also had a greater accumulation of L-lactate and a reduction of glycogen stores. Fights were less costly in terms of injury with a single chemical cue compared with enhanced costs with a multiple sexual cue. The importance of female choice was determined by presenting postmolt females with different sized males. Males were kept in a fixed position, and the majority of females approached and performed courtship behavior to the largest males, demonstrating that females may be selective in terms of size.     

Evidence for trail-pheromone precursor in termiteReticulitermes speratus (Kolbe) (Rhinotermitidae: Isoptera)

Whole body extracts of the termite,Reticulitermes speratus, were subjected to various chemical operations and bioassays to examine the presence of trail-pheromone precursor. Fractions that mainly contained fatty acid esters were obtained from hexane extracts by means of silica gel column chromatography. Trail-following activity of the fractions was activated by alkaline hydrolysis, while the original fractions did not show any conspicuous activity. Bioassay showed that the activity of hydrolyzed product was approximately 20 times as high as the original hexane extract. This suggests that the precursor candidate could be stored in termite bodies as an esterified form. Chemical analyses revealed that the complete structure of the hydrolyzed product was coincident with that of the native pheromone ((Z,Z,E)-3,6,8-dodecatrien-1-ol).     

Epicuticular Wax Chemicals in Zea mays Influence Oviposition in Ostrinia nubilalis

The chemical basis of oviposition elicitation in a generalist herbivore was determined by examination of oviposition responses in Ostrinia nubilalis to corn (Zea mays) chemicals in two-choice laboratory bioassays. A pentane extract of corn leaves stimulated oviposition and the activity persisted for three days, indicating that oviposition in O. nubilalis is elicited by low-volatility chemicals. Chemicals in the extract were fractionated by column chromatography on Florisil, using a sequence of solvents of increasing polarity. Bioassays of Florisil fractions indicated that the stimulants were eluted with nonpolar solvents. Positive bioassay results with an extract prepared by dipping corn leaves in pentane for 20 sec for extraction of leaf surface chemicals suggested that some of the active material was present in the leaf epicuticle. Gas chromatographic analyses and comparisons with retention times of standards suggested the presence of several n-alkanes in the dip extract. Five n-alkanes—hexacosane, heptacosane, octacosane, nonacosane, and tritriacontane—known to be present in the epicuticle of corn leaves were bioassayed, and all five elicited oviposition responses. These results suggest that oviposition elicitation in O. nubilalis is influenced by the presence of n-alkanes in the host plant epicuticle.     

Reinvestigation of Female Sex Pheromone of Processionary Moth (Thaumetopoea pityocampa): No Evidence for Minor Components

The female sex pheromone of the processionary moth Thaumetopoea pityocampa has been reinvestigated to look for possible minor components. Examination by GC-MS and GC-EAD of the contents of virgin female glands, after stimulation with PBAN (pheromone-biosynthesis-activating neuropeptide), showed that the major component, (Z)-13-hexadecen-11-ynyl acetate (1), appears to be the only pheromone compound present in the gland. Comparison of female attractivity with that of the natural extract and synthetic (Z)-13-hexadecen-11-ynyl acetate showed that this chemical is able to elicit a similar activity to that displayed by virgin females in a wind tunnel. In single cell recording experiments, two specialist receptor cell types were found in the trichoid sensilla. One cell type was tuned to enyne acetate 1. The other one was tuned to (Z,Z)-11,13- hexadecadienal and (Z)-13-hexadecen-11-ynal, the major components of the pheromone blend of other Thaumetopoea spp., and constitutes a further example of interspecific inhibitor receptor cells. Our results show that the processionary moth may not need minor components for successful mate recognition.     

Pheromonal basis of courtship behavior in two gypsy moth parasitoids:Brachymeria intermedia (Nees) andBrachymeria lasus (Walker) (Hymenoptera: Chalcididae)

The pheromonal basis of the courtship behavior of two gypsy moth parasitoids,Brachymeria intermedia andBrachymeria lasus, was traced to a single component in each case. This component was isolated by a combination of absorption and gas-liquid chromatography and shown to elicit some of the courtship behavior typical of these species. Bioassays of extracts from several independent techniques for sequestering pheromones, as well as interspecific assays, support this conclusion. Comparative analyses of both male and female extracts by capillary chromatography show the uniqueness of the pheromonal peak to the female volatile profile.     

Interspecific recognition among termites of the genusReticulitermes: Evidence for a role for the cuticular hydrocarbons

Two species of termites,Reticulitermes (lucifugus) grassei andR. (l.) banyulensis, show a high degree of aggressivity toward each other. The epicuticular signature, recognized by contact, can be extracted using organic solvents, and the removal of the signature abolished all types of aggressive behavior. The signature can be transferred to lures, where it triggers interspecies aggression. It was found to be mainly present in the apolar fraction of the cuticular extracts, which contained only hydrocarbons, are determined by GC/MS techniques. Chemical recognition contributes towards isolation of the two species belonging to theR. lucifugus complex.