Responses of fruit flies (Tephritidae: Dacinae) to novel male attractants in north Queensland, Australia, and improved lures for some pest species

Male fruit fly attractants, cue-lure and methyl eugenol (ME), have been successfully used for the last 50 years in the monitoring and control of Dacini fruit flies (Bactrocera and Dacus species). However, over 50% of Dacini are non-responsive to either lure, including some pest species. A new lure, zingerone, has been found to weakly attract cue- and ME-responsive species in Malaysia. In Australia it attracted a weakly cue-responsive minor pest Bactrocera jarvisi (Tryon) and three non-responsive' species. Similar compounds were tested in Queensland and attracted cue- and ME-responsive species and two non-responsive' species. In this study, 14 novel compounds, including raspberry ketone formate (RKF) (Melolure) and zingerone, were field tested in comparison with cue-lure and ME at 17 sites in north Queensland. The most attractive novel lures were isoeugenol, methyl-isoeugenol, dihydroeugenol and zingerone. Several non-responsive' species responded to the new lures: Bactrocera halfordiae (Tryon), a species of some market access concern, was most attracted to isoeugenol; B.barringtoniae (Tryon), B.bidentata (May) and B.murrayi (Perkins) responded to isoeugenol, methyl-isoeugenol and dihydroeugenol; two new species of Dacus responded to zingerone. Bactrocera kraussi (Hardy), a cue-responsive minor pest in north Queensland, was significantly more attracted to isoeugenol than cue-lure. The cue-responsive D.absonifacies (May) and D.secamoneaeDrew were significantly more attracted to zingerone than cue-lure. Bactrocera yorkensisDrew & Hancock, a ME-responsive species was significantly more attracted to isoeugenol, methyl-isoeugenol and dihydroeugenol than ME. The preferential response to RKF or cue-lure was species specific. Six species were significantly more attracted to RKF, including the pests B.tryoni (Froggatt), B.frauenfeldi (Schiner) and minor pest B.bryoniae (Tryon); eight species were significantly more attracted to cue-lure including the pest B.neohumeralis (Hardy). These findings have significance in the search for optimal male lures for pest species elsewhere in the world.

Functional significance of male attractants of Bactrocera tryoni (Diptera: Tephritidae) and underlying mechanisms

This project elucidated functional role of phytochemicals used in the management of pest fruit flies. Comparative behavioural, physiological and genomic approaches revealed that phytochemicals are mediating reproductive fitness by changing pheromonal compound males release and by making them physiologically more active. The possible mechanistic functions are that the phytochemicals act as a pheromone booster and as an energy supplement.

Sexual selection in true fruit flies (Diptera: Tephritidae) : transcriptome and experimental evidences for phytochemicals increasing male competitive ability

In male tephritid fruit flies of the genus Bactrocera, feeding on secondary plant compounds (sensu lato male lures = methyl eugenol, raspberry ketone and zingerone) increases male mating success. Ingested male lures alter the male pheromonal blend, normally making it more attractive to females and this is considered the primary mechanism for the enhanced mating success. However, the male lures raspberry ketone and zingerone are known, across a diverse range of other organisms, to be involved in increasing energy metabolism. If this also occurs in Bactrocera, then this may represent an additional benefit to males as courtship is metabolically expensive and lure feeding may increase a fly's short-term energy. We tested this hypothesis by performing comparative RNA-seq analysis between zingerone-fed and unfed males of Bactrocera tryoni. We also carried out behavioural assays with zingerone- and cuelure-fed males to test whether they became more active. RNA-seq analysis revealed, in zingerone-fed flies, up-regulation of 3183 genes with homologues transcripts to those known to regulate intermale aggression, pheromone synthesis, mating and accessory gland proteins, along with significant enrichment of several energy metabolic pathways and gene ontology terms. Behavioural assays show significant increases in locomotor activity, weight reduction and successful mating after mounting; all direct/indirect measures of increased activity. These results suggest that feeding on lures leads to complex physiological changes, which result in more competitive males. These results do not negate the pheromone effect, but do strongly suggest that the phytochemical-induced sexual selection is governed by both female preference and male competitive mechanisms.

Cuelure but not zingerone make the sex pheromone of male Bactrocera tryoni (Tephritidae: Diptera) more attractive to females

In tephritid fruit flies of the genus Bactrocera Macquart, a group of plant derived compounds (sensu amplo ‘male lures') enhance the mating success of males that have consumed them. For flies responding to the male lure methyl eugenol, this is due to the accumulation of chemicals derived from the male lure in the male rectal gland (site of pheromone synthesis) and the subsequent release of an attractive pheromone. Cuelure, raspberry ketone and zingerone are a second, related group of male lures to which many Bactrocera species respond. Raspberry ketone and cuelure are both known to accumulate in the rectal gland of males as raspberry ketone, but it is not known if the emitted male pheromone is subsequently altered in complexity or is more attractive to females. Using Bactrocera tryoni as our test insect, and cuelure and zingerone as our test chemicals, we assess: (i) lure accumulation in the rectal gland; (ii) if the lures are released exclusively in association with the male pheromone; and (iii) if the pheromone of lure-fed males is more attractive to females than the pheromone of lure-unfed males. As previously documented, we found cuelure was stored in its hydroxyl form of raspberry ketone, while zingerone was stored largely in an unaltered state. Small but consistent amounts of raspberry ketone and β-(4-hydroxy-3-methoxyphenyl)-propionic acid were also detected in zingerone-fed flies. Males released the ingested lures or their analogues, along with endogenous pheromone chemicals, only during the dusk courtship period. More females responded to squashed rectal glands extracted from flies fed on cuelure than to glands from control flies, while more females responded to the pheromone of calling cuelure-fed males than to control males. The response to zingerone treatments in both cases was not different from the control. The results show that male B. tryoni release ingested lures as part of their pheromone blend and, at least for cuelure, this attracts more females.

A highly effective and selective male lure for Bactrocera jarvisi (Tryon) (Diptera: Tephritidae)

Bactrocera jarvisi (Tryon) is a moderate pest fruit fly particularly in northern Australia where mango is its main commercial host. It was largely considered non-responsive to the known male lures. However, male B. jarvisi are attracted to the flowers of Bulbophyllum baileyi, Passiflora ligularis, Passiflora maliformis and Semecarpus australiensis and this paper describes an attempt to determine the attractive compounds in the latter two species through chemical analysis. At about the same time, zingerone was identified as a fruit fly attractant in the flowers of Bulbophyllum patens in Malaysia, and this led the author to speculate that it could be attracting B. jarvisi to the flowers of B. baileyi. Two long-term traps, each with lures containing 2 g of liquefied zingerone and 1 mL maldison EC were established at Speewah, west of Cairns, in November 2001 and retained until April 2007. Over five complete years, 68 897 flies were captured, of which 99.6% were male B. jarvisi. Annual peaks in activity occurred between mid-January and early February, when they averaged 1428.5 +/- 695.6 (mean +/- standard error) male B. jarvisi/trap/week. Very few B. jarvisi were caught between June and September. Among 12 other species of Bactrocera and Dacus attracted to zingerone were the previously non-lure responsive Bactrocera aglaiae, a new species Bactrocera speewahensis, and the rarely trapped Dacus secamoneae. Four separate trials were conducted over 8- to 19-week periods to compare the numbers and species of Bactrocera and Dacus caught by zingerone, raspberry ketone/cue-lure or methyl eugenol-baited traps. Overall, 27 different species of Bactrocera and Dacus were recorded. The zingerone-baited traps caught 97.799.3% male B. jarvisi and no methyl eugenol responsive flies. Significantly more Bactrocera neohumeralis or Bactrocera tryoni were attracted to raspberry ketone/cue-lure than to zingerone (P < 0.001). Zingerone and structurally related compounds should be tested more widely throughout the region.

Cucumber volatile blend, a promising female-biased lure for Bactrocera cucumis (French 1907) (Diptera: Tephritidae: Dacinae), a pest fruit fly that does not respond to male attractants

Bactrocera cucumis (French 1907), the ‘cucumber fruit fly’, is a horticultural pest in Australia that primarily infests cucurbits and has also been recorded from tomatoes, papaw and several other hosts. It does not respond to known male lures, cue-lure and methyl eugenol, making monitoring and control difficult. A cucumber volatile blend lure was recently developed in Hawaii and found to be an effective female-biased attractant for the melon fly B. cucurbitae. This lure was field tested in north Queensland, Australia in McPhail traps in comparison with orange ammonia, Cera Trap® and a control, and was found to more consistently trap B. cucumis than the other lures. B. cucumis were caught at 41% of the cucumber volatile lure trap clearances, compared with 27% of the orange ammonia, 18% of the Cera Trap and 16% of the control trap clearances. The cucumber volatile lure was more attractive to B. cucumis in low population densities and also trapped B. cucumis earlier on average than the other lures. Data analysed from the site with highest trap catches (Spring Creek) showed that the cucumber volatile lure caught significantly more B. cucumis than the other traps in four of the 11 trap clearance periods, and for the remaining clearances, no other trap type caught significantly more flies than the cucumber volatile lure. The cucumber volatile lure had a strong female-biased attraction but it was not significantly more female-biased than orange ammonia or Cera Trap. Cucumber volatile lure traps were cleaner to service resulting in better quality specimens than the orange ammonia trap or Cera Trap. These findings have potential implications for market access monitoring for determining pest freedom, and for biosecurity monitoring programmes in other countries that wish to detect B. cucumis early.

Sexual selection in true fruit flies (Diptera: Tephritidae): transcriptome and experimental evidences for phytochemicals increasing male competitive ability

In male tephritid fruit flies of the genus Bactrocera, feeding on secondary plant compounds (sensu lato male lures = methyl eugenol, raspberry ketone and zingerone) increases male mating success. Ingested male lures alter the male pheromonal blend, normally making it more attractive to females and this is considered the primary mechanism for the enhanced mating success. However, the male lures raspberry ketone and zingerone are known, across a diverse range of other organisms, to be involved in increasing energy metabolism. If this also occurs in Bactrocera, then this may represent an additional benefit to males as courtship is metabolically expensive and lure feeding may increase a fly's short-term energy. We tested this hypothesis by performing comparative RNA-seq analysis between zingerone-fed and unfed males of Bactrocera tryoni. We also carried out behavioural assays with zingerone- and cuelure-fed males to test whether they became more active. RNA-seq analysis revealed, in zingerone-fed flies, up-regulation of 3183 genes with homologues transcripts to those known to regulate intermale aggression, pheromone synthesis, mating and accessory gland proteins, along with significant enrichment of several energy metabolic pathways and gene ontology terms. Behavioural assays show significant increases in locomotor activity, weight reduction and successful mating after mounting; all direct/indirect measures of increased activity. These results suggest that feeding on lures leads to complex physiological changes, which result in more competitive males. These results do not negate the pheromone effect, but do strongly suggest that the phytochemical-induced sexual selection is governed by both female preference and male competitive mechanisms.

Cuelure but not zingerone make the sex pheromone of male Bactrocera tryoni (Tephritidae: Diptera) more attractive to females

In tephritid fruit flies of the genus Bactrocera Macquart, a group of plant derived compounds (sensu amplo ‘male lures’) enhance the mating success of males that have consumed them. For flies responding to the male lure methyl eugenol, this is due to the accumulation of chemicals derived from the male lure in the male rectal gland (site of pheromone synthesis) and the subsequent release of an attractive pheromone. Cuelure, raspberry ketone and zingerone are a second, related group of male lures to which many Bactrocera species respond. Raspberry ketone and cuelure are both known to accumulate in the rectal gland of males as raspberry ketone, but it is not known if the emitted male pheromone is subsequently altered in complexity or is more attractive to females. Using Bactrocera tryoni as our test insect, and cuelure and zingerone as our test chemicals, we assess: (i) lure accumulation in the rectal gland; (ii) if the lures are released exclusively in association with the male pheromone; and (iii) if the pheromone of lure-fed males is more attractive to females than the pheromone of lure-unfed males. As previously documented, we found cuelure was stored in its hydroxyl form of raspberry ketone, while zingerone was stored largely in an unaltered state. Small but consistent amounts of raspberry ketone and β-(4-hydroxy-3-methoxyphenyl)-propionic acid were also detected in zingerone-fed flies. Males released the ingested lures or their analogues, along with endogenous pheromone chemicals, only during the dusk courtship period. More females responded to squashed rectal glands extracted from flies fed on cuelure than to glands from control flies, while more females responded to the pheromone of calling cuelure-fed males than to control males. The response to zingerone treatments in both cases was not different from the control. The results show that male B. tryoni release ingested lures as part of their pheromone blend and, at least for cuelure, this attracts more females.

Evolution of lure response in tephritid fruit flies : phytochemicals as drivers of sexual selection

The males of many Bactrocera species (Diptera: Tephritidae) respond strongly and positively to a small number of plant-derived chemicals (=male lures). Males that have imbibed the lures commonly have a mating advantage over unfed males, but no female benefits have been demonstrated for females mating with lure-fed males. It has been hypothesized that the strong lure response is a case of runaway selection, where males receive direct benefits and females receive indirect benefits via 'sexy sons', or a case of sensory bias where females have a lower threshold response to lures. To test these hypotheses we studied the effects of lure feeding on male mating, remating and longevity; while for females that had mated with lure-fed males we recorded mating refractoriness, fecundity, egg viability and longevity. We used Bactrocera tryoni as our test animal and as lures the naturally occurring zingerone and chemically related, but synthetic chemical cuelure. Feeding on lures provided direct male benefits in greater mating success and increased multiple mating. For the first time, we recorded direct female effects: increased fecundity and reduced remating receptivity. Egg viability did not differ in females mated with lure-fed or unfed males. The life span of males and females exposed to lures was reduced. These results reveal direct, current-generation fitness benefits for both males and females, although the male benefits appear greater. We discuss that while lure response is indeed likely to be a sexual selection trait, there is no need to invoke runaway selection to explain its evolution.

Indirect effects of phytochemicals on offspring performance of Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae)

Phytochemical lures such as methyl eugenol (ME) and cue-lure are used in the management of Bactrocera fruit flies for monitoring and control. These lures are not just attractants, but also trigger physiological changes in males that lead to enhanced mating success. Additionally, in the cue-lure-responsive Bactrocera tryoni, females mated with lure-fed males exhibit changes in fecundity, remating receptivity and longevity. While the lures show current generation effects, no research has been carried out on possible multigenerational effects, although such effects have been hypothesized within a ‘sexy-son’ sexual selection model. In this study, we test for indirect, cross-generational effects of lure exposure in F1offspring of B. tryoni females mated with cue-lure-fed, zingerone-fed and lure-unfed (=control) males. The F1 attributes we recorded were immature development time, immature survival, adult survival and adult male lure foraging. No significant differences were found between treatments for any of the three life-history measurements, except that the offspring sired by zingerone-fed males had a longer egg development time than cue-lure and control offspring. However, indirect exposure to lures significantly enhanced the lure-foraging ability of F1 adult males. More offspring of cue-lure-fed males arrived at a lure source in both large flight cages and small laboratory cages over a 2-h period than did control males. The offspring of zingerone-fed males were generally intermediate between cue-lure and control offspring. This study provides the first evidence of a next generation effect of fruit fly male lures. While the results of this study support a ‘sexy-son’ sexual selection mechanism for the evolution of lure response in Bactrocera fruit flies, our discussion urges caution in interpreting our results in this way.

Volatile compounds from the flowers of spathiphyllum Cannaefolium

Headspace analysis and solvent extraction of the pollenbearing flower spike of Spathiphyllum cannaefolium have been conducted by GC-MS, to determine the basis of the flower spike’s attractancy to certain fruit-fly species. The major components were benzyl acetate, methyleugenol, methylchavicol, p-methoxybenzyl acetate and fatty acids. Benzyl acetate is known to be attractive to D. cueurbitae, D. dorsalis and C. capitata (representing the three different ‘male-lure categories’) and methyleugenol (one of these male-lures) attracts D. cacuminatus, D. dorsalis and D. occipitalis. Thus the odoriferous flowerspike exhibits wide ranging attractancy and hence Spathiphyllum cannaefolium may have some application as a fruit-fly control measure for small orchards where ‘methyleugenol-attracted’ species (e.g. D. cacuminatus, D. dorsalis, D. occipitalis) are the dominant pests.

Is the Marlboro man the only alternative? The role of gender identity and self-construal salience in evaluations of male models

This research examines how men react to male models in print advertisements. In two experiments, we show that the gender identity of men influences their responses to advertisements featuring a masculine, feminine, or androgynous male model. In addition, we explore the extent to which men feel they will be classified by others as similar to the model as a mechanism for these effects. Specifically, masculine men respond most favorably to masculine models and are negative toward feminine models. In contrast, feminine men prefer feminine models when their private self is salient. Yet in a collective context, they prefer masculine models.These experiments shed light on how gender identity and self-construal influence male evaluations and illustrate the social pressure on men to endorse traditional masculine portrayals. We also present implications for advertising practice.

Daddies, assistants and foolsbdifferentiation of male representations in present-day advertising.

This paper explores the way men are represented in present-day advertising. Most gender related studies have concentrated in studying women in advertising and claim that men are still represented as the dominant gender and in more active, independent and functional roles than women. This paper asks whether this still holds for advertising in the beginning of 21st century. Many cultural changes may have broken the earlier stereotypes, for example changes in the family life, attitudes toward various sexual identities, concepts of masculinity and femininity, and changes in cultural style.

Wrapped fragments : Drapery, the eighteenth century portrait bust and the male subject

The depiction of drapery (generalised cloth as opposed to clothing) is a well-established convention of Neo-Classical sculpture and is often downplayed by art historians as of purely rhetorical value. It can be argued however that sculpted drapery has served a spectrum of expressive ends, the variety and complexity of which are well illustrated by a study of its use in portrait sculpture. For the Neo-Classical portrait bust, drapery had substantial iconographic and political meaning, signifying the new Enlightenment notions of masculine authority. Within the portrait bust, drapery also served highly strategic aesthetic purposes, alleviating the abruptness of the truncated format and the compromising visual consequences of the “cropped” body. With reference to Joseph Nollekens’ portraits of English statesman Charles James Fox and the author’s own sculptural practice, this paper analyses the Neo-Classical use of drapery to propose that rendered fabric, far from mere stylistic flourish, is a highly charged visual signifier with much scope for exploration in contemporary sculptural practice.