Pheromone-mediated copulatory responses of the screwworm fly,Cochliomyia hominivorax

A bioassay based on male copulatory responses occurring on contact with dead decoy insects was used to confirm the existence of a sex pheromone in the screwworm fly,Cochliomyia hominivorax. Males responded to female but not male decoys. Mated and virgin females were equally stimulatory. Activity was abolished when females were washed with hexane but partially restored by treatment with crude hexane extract of females. Responses decreased when extracts were diluted and when the number of females extracted per milliliter of hexane was decreased from 20 to 1 in the preparation of extracts concentrated to 0.4 female/l. Sexually mature female decoys of the 009 strain, the most laboratory-adapted of three strains examined in intrastrain tests, produced few copulatory attempts compared with those of Aricruz or DE-9 strains. However, newly emerged 009 as well as Aricruz females elicited responses from about 80% of sexually mature males. Those of the DE-9 strain stimulated fewer than 1%. The observation that 009 females were maximally stimulatory before becoming receptive to mating suggests that these strain differences resulted from laboratory colonization.     

Chemical basis for asymmetric mating isolation between strains of screwworm fly,Cochliomyia hominivorax

Laboratory mating tests and bioassays for a contact, mating-stimulant pheromone were conducted within and between two strains of the screwworm fly,Cochliomyia hominivorax. No strain or sex difference in pheromone activity occurred at emergence. However, the pheromone activity of females increased with age in one strain but declined in the other. Activity also declined in males of both strains but more steeply than in the females. Thus, sexual dimorphism in pheromone activity developed with age in both strains but to differing degrees. The decline in female pheromone activity was partly compensated for within that strain by a higher male responsiveness to pheromone. Female pheromone activity and mating success were positively correlated. Virgin females and those inseminated 24–48 hr previously were equally stimulatory. It appears that the strain differences arose from selection for reduced pheromone activity during laboratory colonization.     

Isolation,identification, and synthesis of male-produced sex pheromone of papaya fruit fly,Toxotrypana curvicauda Gerstaecker (Diptera: Tephritidae)

A male-produced sex pheromone of the papaya fruit fly,Toxotrypana curvicauda Gerstaecker, was isolated from volatiles collected from air passed over calling males and was identified as 2-methyl-6-vinylpyrazine by comparative gas-liquid chromatographic and spectroscopic evidence. Synthetic 2-methyl-6-vinylpyrazine elicited typical pheromonal responses from unmated mature female flies such as walking, running, and flying in an arena bioassay; flying upwind with a zigzag flight pattern; and hovering in the pheromone plume in a wind-tunnel bioassay. These responses were similar quantitatively and qualitatively to responses to naturally occurring pheromone from calling male papaya fruit flies.This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or the recommendation for its use by USDA.     

Synthesis of the male stable fly polyene (Z,Z)-1,7,13-pentacosatriene and its geometrical isomers

The four geometrical isomers of 1,7,13-pentacosatriene were synthesized from 1,7-octadiyne. Two of the required isomers were synthesized using known methodology. Hydrogenation of acetylenic linkages were employed to produce predominantly cis alkenes, and alkali metal/amine reduction was used to produce a trans alkene. It was thus possible to produce the (Z,Z) and the (Z,E) isomers. Methods for olefin inversion were then employed to obtain the other two isomers.     

House fly oviposition inhibition by larvae ofHermetia illucens,the black soldier fly

Wild populations of house flies were inhibited from ovipositing into poultry manure containing larvae of the black soldier fly,Hermetia illucens (L.). A laboratory strain of house fly responded differently, readily ovipositing into manure with lower densities of soldier fly larvae, but avoiding the higher densities tested. The amount of timeH. illucens larvae occupy the manure prior to an oviposition test influences ovipositional responses of house flies. Manure conditioned byH. illucens larvae for 4–5 days did not significantly inhibit house fly oviposition. We suggest that some type of interspecific chemical communication (allomone) is present.Diptera: Stratiomyidae.Portion of an MS thesis by S.W.B.Research partially supported by State and Hatch funds.     

Sex Pheromone of Glossina tachinoides: Isolation, Identification, and Synthesis

Study of lipids from male and female laboratory-reared flies led to the demonstration of a potent contact sex stimulant in extracts and cuticular hydrocarbons of the female tsetse fly Glossina tachinoides (Westwood) against conspecific males. Thin-layer and column chromatography indicated that extracts contained hydrocarbons and saponifiable lipids. Biological activity was found in the alkanes from females, including prominent branched-chain alkanes that were detected by gas chromatography (GC). The alkanes were separated and collected by preparative gas chromatography (GC), and only the 37-carbon region showed biological activity. GC–mass spectrometry showed the major peak contained a mixture of isomeric 11,23-, 13,25- plus a minor amount of 11,21-dimethylheptatriacontane. Two racemic isomers were synthesized, and bioassays showed that the greatest activity was possessed by the 11,23- isomer with somewhat less activity in 13,25-dimethyl heptatria-contane. Dose–response data showed ED₅₀ at 5 g per decoy with solvent-washed males, nonspecific females, or corks as decoys. These alkanes released sexual activity in males that comprised most of the behaviors released by a female fly of the same species.     

Synthesis of the stereoisomers of the female sex pheromone of the Hessian fly,Mayetiola destructor

The female-produced sex pheromone of the Hessian fly,Mayetiola destructor (Say) (Diptera: Cecidomyiidae), has been identified as (10E)-tridecen-2-yl acetate. A flexible synthetic route was developed which allowed access to the chiral and racemic forms of the pheromone, and to the 10Z stereoisomer of the pheromone. The natural compound was determined to have the 2S configuration by hydrolysis of the acetate function, derivatization of the resulting alcohol with (2S)-2-acetoxypropionyl chloride, and capillary gas Chromatographic comparison of the derivative with the corresponding derivatives prepared from the synthetic enantiomers. Trace amounts of the 10Z isomer of the pheromone have also been detected in extracts of female Hessian fly ovipositors, along with (10E)-tridecen-2-ol and 2-tridecanyl acetate. Due to the small quantities of these compounds available from ovipositor extracts, the chirality of the trace components has not yet been determined.     

Age-related response of male melon fliesDacus cucurbitae (Diptera: Tephritidae) to cue-lure

Laboratory-reared and wild adults of the melon fly,Dacus cucurbitae Coquillett, were tested for response to cue-lure at various ages. Virgin laboratory (4, 6, 8, 10, 12, and 14 days old) and wild (10, 12, 14, 16, 18, 20, and 22 days old) flies were released into outdoor field cages and trapped from 0800 until 1600 hr. Response of males to cue-lure increased with age and corresponded with sexual maturity for each strain. Females of both strains were relatively nonresponsive to cue-lure. Failure to eradicate in past male annihilation programs againstD. cucurbitae may be explained in part by the fact that only older males, which may have already mated with gravid females, respond to cue-lure.     

Electroantennographic and coupled gas chromatographic-electroantennographic responses of the mediterranean fruit fly,Ceratitis capitata,to male-produced volatiles and mango odor

We have identified five compounds from the headspace of calling male Mediterranean fruit flies (medfly),Ceratitis capitata (Wiedemann), and three compounds from the headspace of ripe mango (Mangifera indica L). using coupled gas chromatographic-electroantennographic (GC-EAG) recordings, coupled gas chromatographic-mass spectrometric (GC-MS) analysis, and electroantennographic (EAG) assays of standards. The male-produced volatiles eliciting responses from female antennae were ethyl-(E)-3-octenoate, geranyl acetate, (E,E)--farnesene, linalool, and indole. An EAG dose-response test of linalool enantiomers and indole with female medfly antennae showed relatively strong EAG activities, but no significant difference between (R)-(-)-linalool and (S)-(+)-linalool. The three mango volatiles were identified as (1S)-(-)--pinene, ethyl octanoate, and-caryophyllene. In addition, a strong antennal response was recorded from a contaminant,-copaene, present in a commercial sample of-caryophyllene. The EAG response amplitudes from both male and female antennae to the above three mango volatiles were significantly greater than to a hexanol control. For both male and female medfly antennae, the greatest EAG responses were elicited by-caryophyllene followed by ethyl octanoate. The mean EAG responses of female antennae to-caryophyllene and (1S)-(-)--pinene were significantly greater than those of male antennae.     

Analysis,synthesis, formulation,and field testing of three major components of male mediterranean fruit fly pheromone

Three major components, ethyi-(E)-3-octenoate, geranyl acetate, and (E,E)--farnesene, emitted as volatiles by laboratory-reared and wild male medflies were collected and analyzed qualitatively and quantitatively. Peak emission of these compounds occurred during the third to fifth hours of the photophase and differences were observed in the ratios of the three components emitted by male laboratory-reared and wild flies. These three compounds were synthesized, and a method was developed to formulate a synthetic blend that released the compounds in a ratio similar to that emitted by wild male medflies. Attractiveness of the blend to female medflies was demonstrated under field conditions by comparing trap catches. Black spherical traps, baited with the synthetic blend to release 1.6 male equivalents, caught significantly more females than blank traps and traps from which the blend released was 0.3, 3.2 or 6.4 male equivalents.This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or recommendation for its use by USDA.     

Responses of Tea Tussock Moth, Euproctis pseudoconspersa, to Its Pheromone, (R)-10,14-Dimethylpentadecyl Isobutyrate, and to the S-Enantiomer of Its Pheromone

Field trials were conducted with each synthetic enantiomer (>98% ee) and blends of the two synthetic enantiomers of the female-produced sex pheromone (10,14-dimethylpentadecyl isobutyrate) of the tea tussock moth, Euproctis pseudoconspersa. Male moths were attracted to each enantiomer alone and to various blends of them. Short syntheses of both enantiomers of the pheromone from commercially available (R)- and (S)-citronellyl bromide and a method of checking the enantiomeric purity of the citronellyl bromide enantiomers are described.     

Accumulation ofDendrobium superbum (orchidaceae) fragrance in the rectal glands by males of the melon fly,Dacus cucurbitae

4-(4-Hydroxyphenyl)-2-butanone was characterized from flowers of the orchidDendrobium superbum as a specific attractant factor for the male melon fly,Dacus cucurbitae. The male flies compulsively licked the flower surface and sequestered the compound in significant quantities in their rectal glands. The compound was detected within 6 hr after ingestion and was retained for more than six days in the rectal gland sacs.     

Synthesis of diastereomeric mixture of 15,19,23-trimethylheptatriacontane,contact sex pheromone of tsetse fly,Glossina morsitans morsitans westwood

A nine-step synthesis is described for a diastereomeric mixture of 15,19,23-trimethylheptatriacontane, a contact sex pheromone ofGlossina morsitans morsitans Westwood. The compound has been synthesized by means of double alkylation of diethyl 3-oxoglutarate (DEOG) with 3-methyl-2-heptadecenyl methanesulfonate, which was readily prepared from 1-hexadecene, as the key step.This study constitutes Part XII of Selective Alkylation of Diethyl 3-Oxoglutarate. Part XI of this series, see Naoshima et al. (1984).     

Simultaneous Disruption of Pheromone Communication in Choristoneura rosaceana and Pandemis limitata with Pheromone and Antagonist Blends

In British Columbia, trapping and wind-tunnel studies demonstrated that (Z)-9-tetradecenyl acetate (Z9–14:OAc), a minor component of the sex pheromone for Pandemis limitata, acted as a pheromone antagonist to a sympatric species, Choristoneura rosaceana. Addition of >1% Z9–14:OAc to the four-component C. rosaceana pheromone in a wind tunnel resulted in significant reductions in the proportion of male C. rosaceana that wing fanned, locked on to the plume in flight, oriented upwind, and made source contact, compared to the responses to the pheromone alone. Disruption of pheromone communication was tested in 33.3 × 33.3-m plots, at a release rate of 10 mg/ha/hr using Conrel fiber dispensers. Z9–14:OAc applied alone did not disrupt orientation to virgin-female-baited traps for either C. rosaceana or P. limitata. A 1:1 mixture of Z9–14:OAc and the four-component C. rosaceana pheromone was as effective as the pheromone alone at disrupting orientation of C. rosaceana males to virgin-female-baited traps, demonstrating that disruption apparently did not occur through false-trail following. The 1:1 mixture of Z9–14:OAc and the C. rosaceana pheromone also reduced catches of P. limitata males in virgin-female-baited traps, but not significantly more than the 83% disruption caused by the pheromone alone. Therefore, the C. rosaceana pheromone could be used alone or with Z9–14:OAc to disrupt communication and, presumably, mating in both leafrollers simultaneously.     

Pungent spices,ground red pepper,and synthetic capsaicin as onion fly ovipositional deterrents

In laboratory choice experiments, the spices dill, paprika, black pepper, chili powder, ginger, and red pepper deterredDelia antiqua oviposition by 88–100%. Dose-response choice tests demonstrated that 1 mg of ground cayenne pepper (GCP) placed within 1 cm of artificial onion foliage reduced oviposition by 78%. A synthetic analog of capsaicin, the principal flavor ingredient of red peppers, deterred oviposition by 95% when present at 320 ppm in the top centimeter of sand (the ovipositional substrate). However, in no-choice conditions 10 mg GCP was not an effective deterrent. Sevana Bird Repellent and Agrigard Insect Repellent both use red pepper as a principal ingredient; at recommended field rates, neither of these materials was an effective ovipositional deterrent either in laboratory or field. Capsaicin-based materials do not appear to be candidates for onion maggot control via behavioral modification.Paper No. 12514 of the Michigan Agricultural Experiment Station.     

Alarm Pheromone System of the Western Conifer Seed Bug, Leptoglossus occidentalis

The alarm pheromones for adult and nymphal western conifer seed bugs, Leptoglossus occidentalis, were collected from the headspace volatiles of agitated bugs and from extracted adult thoraxes and nymphal abdomens. Adult bugs secreted a blend from the metathoracic glands that consisted of hexyl acetate, hexanal, hexanol, heptyl acetate, and octyl acetate (ratio of 152:103:8:1.5:1). Nymphal alarm pheromone produced by the dorsal abdominal glands consisted of (E)-2-hexenal. Agitated adults emitted 24% of the pheromone contained within the glands, while nymphs released 33% of their constitutive supply. The complete blend from both adults and nymphs, tested in a laboratory headspace bioassay, elicited a dispersal (or alarm) response in >70% of individuals tested. Nymphs in the field exposed to synthetic adult or nymphal pheromones, or a mixture of both, responded with >50% dispersing. When single components were tested on adults reared under summer conditions in a forced-air one-way bioassay, hexanal and hexyl acetate, the major components of the secretion, were responsible for eliciting the alarm response. Adults collected in the fall from the field were unresponsive to the tested blend, suggesting that adults seeking aggregation sites in the fall become refractory to alarm pheromone stimuli that would cause aggregations to disperse. The weak dispersal responses elicited in both adults and nymphs by either nymphal or adult pheromones are consistent with a tradeoff in the advantage gained by avoiding predation and the disadvantage of leaving a food source. Because of these weak responses, use of alarm pheromones as pest management tools against L. occidentalis is unlikely.     

Laboratory and Field Study of the Attraction of Male Pea Midges, Contarinia pisi, to Synthetic Sex Pheromone Components

Behavioral activity of the recently identified sex pheromone components of the pea midge, Contarinia pisi, (2S,11S)-diacetoxytridecane, (2S,12S)-diacetoxytridecane, and 2-acetoxytridecane, was tested in wind tunnel and field-trapping experiments. In the wind tunnel, the attractancy of the three-component blend in a 7 : 10 : 0.1 ratio (following the above order, mimicking the ratios found in gland extract) did not differ significantly from female gland extract, whereas a mixture of the two major components (7 : 10) only attracted 2% of the males to the source. In the field, traps baited with the three-component blend caught by far the largest number of males. Traps baited with the two major components only caught slightly more than the blank traps, and catches in traps baited with 2-acetoxytridecane alone did not differ from catches in the blank traps. Traps baited with the racemate of all three components did not catch more than the blank traps, indicating that some of the enantiomers are inhibitory.     

Heritable Variation in the Sex Pheromone of the Almond Moth, Cadra cautella

The sex pheromone of the female almond moth, Cadra cautella, constitutes a highly variable signal. Age and period of the L/D cycle had significant effects on the variation in titers of (Z,E)-9,12-tetradecadienyl acetate (Z9,E12-14:Ac) and (Z)-9-tetradecenyl acetate (Z9-14:Ac) and the ratio of Z9,E12-14:Ac to Z9-14:Ac. Across age classes, minimum and maximum mean titers (ng +/- SE) of Z9,E12-14:Ac and Z9-14:Ac ranged from 8.7 +/- 0.46 to 21 +/- 1.0 and from 2.0 +/- 0.14 to 2.9 +/- 0.15, respectively; the mean ratio of Z9,E12-14:Ac to Z9-14:Ac ranged from 5.2 +/- 0.21 to 11 +/- 0.40. The titers of Z9,E12-14:Ac and Z9-14:Ac and the ratio of Z9,E12-14:Ac to Z9-14:Ac were highest at the onset of the scotophase and lowest at the onset of the photophase. Similarly, the titer of Z9,E12-14:Ac and the ratio of Z9,E12-14:Ac to Z9-14:Ac were highest in females sampled 1 d postemergence and declined over all age classes. The titer of Z9-14:Ac increased from day 1 to day 2, and then declined to levels equivalent to day 1. Analysis of pupal and adult mass demonstrated a positive correlation (r = 0.874, P < 0.001); however, the titer of neither Z9,E12-14:Ac or Z9-14:Ac nor the ratio of Z9,E12-14:Ac to Z9-14:Ac were significantly correlated with pupal mass. Age-related variations in pheromone titer and ratios were heritable. The narrow-sense heritability of the observed variation in 1-d-old females, 1 hr into the scotophase is 1.2 +/- 0.32, 0.75 +/- 0.24, and 0.46 +/- 0.17 for the titer of Z9,E12-14:Ac and Z9-14:Ac and the ratio of Z9,E12-14:Ac to Z9-14:Ac, respectively. A significant additive genetic correlation was observed between that of Z9,E12-14:Ac and Z9-14:Ac, but not between that of either Z9,E12-14:Ac or Z9-14:Ac and the ratio of Z9,E12-14:Ac to Z9-14:Ac. The results of the genetic analyses suggest that the traits of titer of Z9,E12-14:Ac and Z9-14:Ac have a greater potential to respond to selection than the trait of ratio of Z9,E12-14:Ac to Z9-14:Ac.     

Partial characterization and HPLC isolation of bacteria-produced attractants for the Mexican fruit fly,Anastrepha ludens

Methods were developed to collect and isolate volatile chemicals produced by aStaphylococcus bacterium in tryptic soy culture that are attractive to protein-hungry adult Mexican fruit flies. Centrifugation of bacteria culture yielded a slightly attractive pellet containing most of the bacteria cells and a highly attractive supernatant. Supernatant filtered to remove the remaining bacteria was as attractive as the unfiltered supernatant. Filtrate at pH 7 and above was much more attractive than filtrate at pH 5 and below. Most of the attractiveness was retained on strong cation exchange media under acidic conditions and eluted with base. Attractive principles could not be trapped on adsorbents such as Porapak Q or extracted with organic solvents from aqueous preparations, but they were easily collected by headspace sweeping with steam. The attractive components were efficiently concentrated by rotary evaporation of steam distillate at pH 5, but at higher pH much of the attractiveness distilled. A reverse-phase HPLC method using a negative counter-ion was developed to separate and collect attractive components of concentrated steam distillate. Attractive fractions collected using this method were concentrated and injected onto silica HPLC. Activity eluted from silica in two distinct bands. Results suggest that the most attractive components of the bacterial odor are highly polar, low-molecular-weight amines.Diptera: Tephritidae.     

Female-Produced Sex Pheromone of the Predatory Bug Geocoris punctipes

A compound identified from air-entrained volatiles produced by adult female Geocoris punctipes attracted male bugs and stimulated males to investigate nearby moving objects of the appropriate size in their search for females. The compound was identified as (E)-2-octenyl acetate, a relatively common component of the volatile semiochemicals produced by a number of heteropteran species. This compound comprised a significant proportion of the female volatiles, whereas it was detected in only trace amounts in volatiles collected from live males. Other components in the extracts from adults of both sexes included (E)-2-hexenyl acetate, (E)-2-octenal, and several saturated hydrocarbons, but these components were not part of the attractant. These compounds plus (E)-2-hexenal, (E)-4-oxo-2-hexenal, and (E)-2-decenal were found in extracts of homogenized adults, whereas the cast skins from late instar nymphs contained (E)-2-octenal, (E)-4-oxo-2-octenal, (E)-2-octenoic acid, and several saturated hydrocarbons.