Comparison of volatiles emitted by male caribbean and mexican fruit flies

Volatiles emitted byAnastrepha suspensa andAnastrepha ludens males were trapped and compared by GC-MS. Both species emitted previously reported nine-carbon alcohols, (Z)-3-nonenol and (Z,Z)-3,6-nonadienol, and epimeric lactones, anastrephin and epianastrephin. A third isomeric lactone, the macrolide suspensolide, which was previously known only fromA. suspensa is reported here for the first time in the volatiles ofA. ludens. We also report that both species released different proportions of the same three sesquiterpene hydrocarbons:-farnesene,-bisabolene, and-trans-bergamotene. The-bisabolene was isolated in sufficient quantity fromA. suspensa volatiles to establish its absolute configuration as the (R)-(+)-enantiomer. Some plausible biosynthetic relationships of farnesol to the isoprenoid lactones and sesquiterpenes identified in this study are discussed. Finally, we report thatA. suspensa produces the monoterpene (Z)--ocimene whileA. ludens volatiles contained limonene.     

Caribbean fruit fly,Anastrepha suspensa (Loew), attraction to host fruit and host kairomones

Extracts of 22 fruits were tested for their attractancy toAnastrepha suspensa (Loew), the Caribbean fruit fly. Box-orange, calamondin, carambola, cattley guava, loquat, and Surinam-cherry were about equal in attractiveness to males and females. Nine synthetic chemicals, including four found in box-orange ripe seed, were attractive to females. Five synthetic chemicals, including two in box-orange ripe seed, were attractive to males. Farnesol,-phellandrene, and 3-carene were highest in attractiveness to both males and females. Females were more attracted than males to 12 synthetic chemicals. These data suggest that host chemicals serve as attractants and that female and male specific attractants and traps could be developed from host kairomone data. These data also suggest that the volatilization of chemicals from water may play an important role in kairomone biology.     

Behavioral responses of male and female Mexican fruit flies,Anastrepha ludens,to male-produced chemicals in laboratory experiments

The behavioral responses of male and female Mexican fruit flies elicited by male abdominal extracts were measured in laboratory cages where pheromone was applied to the undersides of some leaves on a treated tree but to none of the leaves on a control tree. After arrival to the treated tree, females came directly to pheromone sources. Females on the treated tree visited leaves and fought other females at higher rates than on the control tree. Females stayed on treated leaves and trees longer than on control leaves and trees. In separate experiments, the number of males on pheromone-treated trees and leaves was higher than on controls, but other behavior was unchanged. The results indicate that the pheromone stimulates a complex of behavior involved in the mating ecology of the species.     

Behavioral responses of female Mexican fruit flies,Anastrepha ludens,to components of male-produced sex pheromone

The behavioral responses of virgin female Mexican fruit flies elicited by components and combinations of the components of male-produced pheromone were measured in a laboratory wind-tunnel bioassay where test chemicals were applied to the undersides of some leaves on a treated tree but to none of the leaves of a control tree. Only treatments containing at least (Z)-3-nonenol and/or (Z,Z)-3,6-nonadienol in combination with (S,S)-(–)-epianastrephin elicited strong behavioral responses. Responses included attraction to the vicinity of the pheromone but not to point sources, increased searching rate, changes in searching strategy, and agonism. The results support a model of pheromone-component function in which components act as a unit to stimulate all behaviors of the pheromone-mediated behavioral repertoire.Diptera: Tephritidae.     

A four-component attractant for the mexican fruit fly,Anastrepha ludens (Diptera: Tephritidae), from host fruit

Sixteen chemicals found in fermented chapote fruit odor were evaluated as attractants for hungry adult Mexican fruit flies. Ethyl octanoate, ethyl benzoate, terpinyl acetate, ethyl salicylate, and (–)--copaene proved slightly attractive. Several of the chemicals also were tested for their ability to increase the attractiveness of the previously developed chapote-derived attractant (CEH) consisting of 1,8-cineole, ethyl hexanoate, and hexanol. Combinations containing CEH with ethyl octanoate, ethyl benzoate, 4-terpineol, (–)--cubebene, or-terpineol were significantly more attractive than CEH alone. The two most attractive four-component combinations were ethyl octanoate with CEH (CEHO) and ethyl benzoate with CEH. No combinations containing greater numbers of chemicals were significantly more attractive than CEHO. Therefore, CEHO was selected for further study in this paper. Of CEHO component ratios that were tested, the most attractive was 1011100 for the chemicals 1,8-cineole, ethyl hexanoate, hexanol, and ethyl octanoate, respectively. Formulations of CEHO into rubber septa and polyvinyl chloride (PVC) were aged 0–15 days and tested againstTorula yeast in competing McPhail traps in a flight chamber. Summed over all lure ages, rubber septa and PVC dispensers, respectively, were 1.2 and 1.5 times more attractive thanTorula yeast. PVC dispensers aged 10–15 days were approximately 2.1 times more attractive thanTorula yeast.     

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.     

Quantitative analysis of pheromone production in irradiated Caribbean fruit fly males,Anastrepha suspensa (Loew)

Pheromonal volatiles emitted by irradiated and control 5- to 11-day-old Caribbean fruit flies,Anastrepha suspensa (Loew), were collected on Tenax adsorbent filters and quantified by gas chromatography (GC). The components released were identified by comparison of retention times on GC and by mass spectrometry (MS) with authentic synthetic standards. Pharate adults were irradiated with gamma rays from a⁶⁰Co source at a dose rate of 10.3 Gray (Gy)/min. The total dosages given were 30, 50, 70, and 100 Gy. Pheromone volatiles were collected from adult males when they were between 5 and 11 days of age. The compounds quantified were (Z)-3-nonenol and (Z, Z)-3,6-nonadienol, which eluted from the GC column together and were quantified as one peak,-bisabolene, suspensolide, anastrephin, and epianastrephin. Irradiation with 30 Gy did not significantly reduce any pheromonal components, nor did it change the pheromonal blend. In contrast, suspensolide and bisabolene were significantly reduced in flies irradiated with 50 Gy, while the nonenols and epianastrephin were reduced at the 70-Gy dose. Irradiation with the 100-Gy dose reduced all components with the exception of suspensolide.University of Florida Agric. Exper. Sta. Journal Series No.R-03156.     

Residual activity of oviposition-deterring pheromone inRhagoletis pomonella (Diptera: Tephritidae) and female response to infested fruit

Under dry conditions, oviposition-deterring pheromone (ODP) of the apple maggot fly (Rhagoletis pomonella Walsh) on host fruit proved deterrent to ovipositing females for at least three weeks, with a half-life of ca. 11 days. There was no difference in decline of residual activity under lab vs. field conditions or between fly-deposited ODP vs. an application of a water extract of ODP. A decline in pheromone activity resulted from exposure to both natural and simulated rainfall. For natural rainfall, greatest losses (50– 61%) in activity resulted from high-intensity rains, with substantially less activity lost (13–35%) following light or moderate intensity rains.R. pomonella females discriminated against fruit without ODP but with conspecific larvae. Discrimination against infested fruit was manifested within fewer days following infestation of small fruit (9 mm diam.) as compared to larger fruit (15 mm diam.).     

Distance of response to host tree models by female apple maggot flies,Rhagoletis pomonella (Walsh) (Diptera: Tephritidae): Interaction of visual and olfactory stimuli

Mature female apple maggot flies,Rhagoletis pomonella (Walsh), were released individually onto a single potted, fruitless hawthorne tree in the center of an open field. The tree was surrounded by four 1-m² plywood host tree models painted green or white, with or without synthetic host fruit odor (butyl hexanoate), and placed at one of several distances from the release tree. Each fly was permitted to forage freely on the release tree for up to 1 hr, or until it left the tree. Flies left the tree significantly sooner when green models with host fruit were present at 0.5, 1.5, or 2.5 m distance from the release tree than when these models were placed at a greater distance (4.5 m) from the release tree or when no models were present. Flies responded detectably to 1-m² models without odor up to a maximum distance of 1.5 m. These results suggest that female apple maggot flies did not detect green 1-m² models with odor 4.5 m away or models without odor 2.5 m or more away. Flies responded to white models with and without odor to a much lesser extent, both in terms of response distance and flight to and alightment upon models. Increasing model size to 2 m² increased the distance to 2.5 m at which flies responded to green models without odor. Decreasing model size to 0.5 m² reduced fly responsiveness to green or white models. The presence of host fruit odor alone, without the visual stimulus of a green model, did not influence residence time on the release tree.     

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.     

Deterrence of repeated oviposition by fruit-marking pheromone inCeratitis capitata (Diptera: Tephritidae)

During ovipositor dragging on the fruit surface following egg laying in hawthorne fruit,Ceratitis capitata (Wiedemann) females deposit an unidentified pheromone that deters repeated oviposition attempts in that fruit. The pheromone proved water soluble and, when collected and sprayed in aqueous solution onto uninfested fruits in laboratory cages, effectively deterred boring attempts byC. capitata females of wild origin for at least 6 days (termination of test). A laboratory population ofC. capitata cultured on artificial media for more than 200 generations deposited pheromone that proved equally as deterrent to wild fly oviposition as pheromone from wild flies. However, lab fly oviposition was not effectively deterred by the presence of pheromone. The ecological significance of the pheromone is discussed.     

NMR spectral assignment of lactone pheromone components emitted by Caribbean and Mexican fruit flies

By utilizing one- and two-dimensional nuclear magnetic resonance techniques, the complete assignments of the proton and carbon spectra of the lactones anastrephin, epianastrephin, and suspensolide have been accomplished. These compounds are pheromone components for both the Caribbean and Mexican fruit flies. The relative stereochemistries of anastrephin and epianastrephin were demonstrated by nuclear Overhauser difference spectroscopy. With complete spectral assignments now available, biosynthesis of these molecules may be studied by feeding specific isotopically labeled nutrients to flies and subsequently analyzing the volatiles produced for the presence and position of the labelling isotope.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.     

A novel attractant for Mexican fruit fly,Anastrepha ludens,from fermented host fruit

Chemicals from fermented chapote fruit were identified and evaluated as attractants for hungry adult Mexican fruit flies in laboratory and greenhouse bioassays. Twenty-eight chemicals identified from an attractive gas-chromatography fraction were as attractive as a chapote volatiles extract (CV) when mixed in the same amounts found in CV. Sixteen of the chemicals were slightly attractive to flies when tested individually. A mixture containing 15 of the chemicals by design and the 16th as an impurity, in arbitrary concentrations, was at least as attractive as the original CV. In a series of experiments, the number of chemicals was reduced to three by elimination of unnecessary components. The three-component mixture retained the attractiveness of the 15-component mixture. The three chemicals were 1,8-cineole, ethyl hexanoate, and hexanol (CEH). Attractiveness of the three-chemical mixture was equal to the sum of the attractiveness of the three individual components, suggesting that each chemical binds to a different receptor type that independently elicits partial attraction behavior. Optimal ratios were 1011 of the three chemicals, respectively. Optimal test quantities ranged between 0.4–4g of 1,8-cineole and 40–400 ng each of ethyl hexanoate and hexanol applied to filter paper in the laboratory bioassays. A neat 1011 mixture of the chemicals was 1.8 times more attractive than aqueous solutions ofTorula dried yeast and borax to starved 2-day-old flies when the lures were tested in competing McPhail traps in a large greenhouse cage.Diptera: Tephritidae.     

Attractants fromStaphylococcus aureus cultures for Mexican fruit fly,Anastrepha ludens

Volatile chemicals from tryptic soy broth cultures ofStaphylococcus aureus that attract sugar-fed, protein-hungry adult Mexican fruit flies were identified. Chemicals identified from the headspace above the filtrate of the bacterial cultures were ammonia, trimethylamine, isoamylamine, 2-methylbutylamine, 2,5-dimethylpyrazine, and acetic acid. Each chemical attracted flies. A mixture of the chemicals in the same concentrations as were found in the bacterial filtrate was 89% as effective in attracting flies as the bacterial filtrate in laboratory bioassays. Additional chemicals were identified from various concentrated or pH altered preparations made from the filtrate. Many of these chemicals also attracted flies. One of these chemicals, dimethylamine, was the most effective chemical identified. The use of solid-phase microextraction for volatile collection and of thick-film (5-µm) capillary GC columns was essential to the success of this work.     

Attraction ofCeratitis capitata (Diptera: Tephritidae) flies to odor of coffee fruit

On potted nonfruiting host trees in outdoor field cages, we evaluated attraction of released mature laboratory-cultured or wild-origin Mediterranean fruit flies (medflies) to odor of freshly picked fruit of host and nonhost plants. Odor of ripe intact or crushed coffee fruit (the presumed ancestral host of medflies) was significantly more attractive than odor of ripe intact or crushed fruit of five lower-ranking hosts and three nonhosts. Odor of crushed coffee fruit was significantly more attractive than odor of intact coffee fruit. Odor of ripe or near-ripe coffee fruit was significantly more attractive than odor of unripe coffee fruit. Immature females (without eggs) were significantly more attracted to odor of a proteinaceous food lure than to odor of ripe coffee fruit, whereas the reverse was true for mature females carrying a high egg load. In some trials, males proved as discriminating as females in favor of coffee fruit odor, but in several other trials males were less discriminating than females. Response patterns of mature laboratory-cultured females were similar to those of mature wild-origin females. In a field of coffee plants, attraction of natural-population females was significantly greater to odor of ripe coffee fruit than to water but was not greater than attraction to odor of proteinaceous food. Findings are discussed in relation to potential use of synthetic volatiles of coffee or other host fruit in traps for monitoring or controlling medflies.     

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.     

Chemical studies of rectal gland secretions of some species ofBactrocera dorsalis complex of fruit flies (diptera: Tephritidae)

Male-produced rectal gland secretions of a number of species now considered to be members of theBactrocera dorsalis complex of fruit flies have been examined by combined gas chromatography-mass spectrometry. The structures of a number of previously unreported compounds have been confirmed by synthesis and Chromatographic comparisons. Compounds identified in these secretions include fatty acids, esters, amides, keto alcohols, diols and spiroacetals. These chemical findings are in agreement with taxonomic revisions based on other criteria.     

Trimedlure enantiomers: Differences in attraction for mediterranean fruit fly,Ceratitis capitata (Wied.) (Diptera: Tephritidae)

The most biologically active enantiomer of trimedlure, a synthetic lure attractive to male Mediterranean fruit flies, is the 1S,2S,4R enantiomer of isomer C, the fert-butyl ester of ris-4-chloro-trans-2-methylcyclohexanecarboxylic acid. We also determined that the 1R,2R,5S enantiomer of isomer A is significantly more attractive than its optical antipode. Essential differences in the current synthetic work that are critical to possible commercialization of this preparation are detailed herein.Deceased.     

Relationship of sexual maturation rate to response of oriental fruit fly strains (Diptera: Tephritidae) to methyl eugenol

Laboratory-reared and wild, fruit-reared adults of the Oriental fruit fly,Dacus dorsalis Hendel, were tested for response to methyl eugenol at various ages. Virgin laboratory (2, 4, 6, 8, and 10 days old) and wild (7, 11, 15, 19, and 23 days old) flies were released into an outdoor field cage and trapped over a two-day period. Response of males increased with age as ca. 32% and 22% of laboratory and wild males responded at 2 and 7 days of age, respectively, while ca. 93% of both strains responded at 10 and 23 days of age, respectively. These correspond approximately to the ages at which they reach sexual maturity. Female response did not increase with age and fluctuated between 15% and 29% for the laboratory strain and 10% and 45% for the wild strain. The age-related response profiles, when integrated with sexual maturation curves, indicate that one of the major reasons the male-annihilation technique is effective is because methyl eugenol is able to attract 40–50% of male flies prior to the onset of sexual maturation.     

Attraction of 3-Methyl-1-Butanol and Ammonia Identified from Enterobacter agglomerans to Anastrepha suspensa

Tests demonstrated that volatile chemicals emitted from Enterobacter agglomerans, a bacterium that has been isolated from adults as well as fruit infested with larvae of the Caribbean fruit fly, Anastrepha suspensa (Loew) and other pest fruit flies, are attractive to female A. suspensa in laboratory bioassays. 3-Methyl-1-butanol and ammonia were identified as the two primary volatile chemicals released from active cultures of E. agglomerans. No 3-methyl-1-butanol and little ammonia (16.0 g/hr) are released from sterile tryptic soy agar plates. E. agglomerans-inoculated tryptic soy agar plates, however, released an average of 1.5 ± 0.53 g/hr 3-methyl-1-butanol and 332.9 ± 239.16 g/hr ammonia after 24 hr of growth. 3-Methyl-1-butanol lures were formulated in a membrane-based system to provide a constant release rate of synthetic chemical. Release rates ranged from 0.046 ± 0.007 to 12.16 ± 2.76 g/hr. In laboratory tests, equal numbers of females were captured in response to ammonium carbonate lures that released ammonia at the rate of 100 g/hr and to 3-methyl-1-butanol lures that released 12.16 ± 2.756 g/hr of synthetic material. The combination of the two lures was more attractive than ammonia alone. Availability of lures formulated for a range of 3-methyl-1-butanol release rates will facilitate field tests of this putative microbial attractant and may lead to a better understanding of the role of bacteria in the ecology of pest fruit flies.