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The tribe Dacini (Diptera: Tephritidae) contains over 930 recognised species and has been widely studied due to the economic importance of some taxa, such as the Oriental fruit fly Bactrocera dorsalis. Despite the attention this group has received, very few phylogenetic reconstructions have comprehensively sampled taxa from a single biogeographic region, thereby limiting our capacity to address more targeted evolutionary questions. To study the evolution of diet breadth and male lure response, two key traits fundamental to understanding dacine diversity and the biology of pest taxa, we analysed 273 individuals representing 144 described species from Australia (80% continental coverage), the Pacific, and select close relatives from South-east Asia to estimate a dated molecular phylogenetic reconstruction of the Dacini. We utilised seven loci with a combined total of 4,332 nucleotides, to estimate both Bayesian and Maximum Likelihood phylogenies of the tribe. Consistent with other molecular phylogenies of the tribe, there was a high level of disagreement between the placement of species in the phylogeny and their current subgeneric and species-complex level taxonomies. The Australian fauna exhibit high levels of endemism, with radiations of both exclusively Australian clades, and clades that originate elsewhere (e.g. the Bactrocera dorsalis species group). Bidirectional movement of species has occurred between Papua New Guinea and Australia, with evidence for multiple incursions over evolutionary time. The Bactrocera aglaiae species group emerged sister to all other Bactrocera species examined. Divergence time estimates were ∼ 30 my younger than previously reported for this group, with the tribe diverging from its most recent common ancestor ∼ 43 mya. Ancestral trait reconstruction and tests for trait phylogenetic signal revealed a strong signal for the evolution of male lure response across the tree, with cue-lure/raspberry ketone lure response the ancestral trait. M

The tropical fruit fly (Diptera: Tephritidae: Dacinae) fauna of Australia has been reasonably well studied using the male lures methyl eugenol and cue-lure. However, there has been little sampling of biodiverse Gondwanan rainforests of eastern Australia. Additionally, recently identified male lures have trapped new, or previously non-responsive species in northern Australia, south-east Asia and the Pacific. We wanted to determine if previously unknown species exist in these biodiverse and poorly sampled areas. Therefore, we conducted fruit fly trapping surveys using the male lures methyl eugenol, cue-lure, isoeugenol, methyl isoeugenol, dihydroeugenol, zingerone and protein baits. Trapping targeted previously known locations of rare species, and remnant Gondwanan forests of eastern Australia between 2017 and 2019. We recorded new distributions for “Bactrocera aurea” (May) and occurrences of rare species “Bactrocera mutabilis” (May) and “Bactrocera brunnea” (Perkins and May). This represented the first record of “Bactrocera brunnea” in over 25 years. Additionally, new lure responses were recorded for previously non-responsive “Bactrocera mutabilis”, and a single “Bactrocera phaleriae” (May); both trapped with isoeugenol. Bactrocera (Bactrocera) clarkei sp. n., is described from Couchy Creek Nature Reserve and the Border Ranges National Park, New South Wales.

The cue-lure-responding New Guinea fruit fly, Bactrocera trivialis, poses a biosecurity risk to neighbouring countries, e.g., Australia. In trapping programs, lure caught flies are usually morphologically discriminated from non-target species; however, DNA barcoding can be used to confirm similar species where morphology is inconclusive, e.g., Bactrocera breviaculeus and B. rufofuscula. This can take days—and a laboratory—to resolve. A quicker, simpler, molecular diagnostic assay would facilitate a more rapid detection and potential incursion response. We developed LAMP assays targeting cytochrome c oxidase subunit I (COI) and Eukaryotic Translation Initiation Factor 3 Subunit L (EIF3L); both assays detected B. trivialis within 25 min. The BtrivCOI and BtrivEIF3L assay anneal derivatives were 82.7 ± 0.8 °C and 83.3 ± 1.3 °C, respectively, detecting down to 1 × 101 copies/µL and 1 × 103 copies/µL, respectively. Each assay amplified some non-targets from our test panel; however notably, BtrivCOI eliminated all morphologically similar non-targets, and combined, the assays eliminated all non-targets. Double-stranded DNA gBlocks were developed as positive controls; anneal derivatives for the COI and EIF3L gBlocks were 84.1 ± 0.7 °C and 85.8 ± 0.2 °C, respectively. We recommend the BtrivCOI assay for confirmation of suspect cue-lure-trapped B. trivialis, with BtrivEIF3L used for secondary confirmation when required.

Wolbachia are widespread endosymbionts that affect arthropod reproduction and fitness. Mostly maternally inherited, Wolbachia are occasionally transferred horizontally. Previously, two Wolbachia strains were reported at low prevalence and titres across seven Australian tephritid species, possibly indicative of frequent horizontal transfer. Here, we performed whole-genome sequencing of field-caught Wolbachia-positive flies. Unexpectedly, we found complete mitogenomes of an endoparasitic strepsipteran, Dipterophagus daci, suggesting that Wolbachia in the flies are linked to concealed parasitisation. We performed the first genetic characterisation and detected D. daci in Wolbachia-positive flies not visibly parasitised, but most Wolbachia-negative flies were D. daci-negative, presumably reflecting polymorphism for the Wolbachia infections in D. daci. We dissected D. daci from stylopised flies and confirmed that Wolbachia infects D. daci, but also found Wolbachia in stylopised fly tissues, likely somatic, horizontally transferred, non-heritable infections. Furthermore, no Wolbachia cif and wmk genes were detected, and very low mitogenomic variation in D. daci across its distribution. Therefore, Wolbachia may influence host fitness without reproductive manipulation. Our study of 13 tephritid species highlights that concealed early stages of strepsipteran parasitisation led to the previous incorrect assignment of Wolbachia co-infections to tephritid species, obscuring ecological studies of this common endosymbiont and its horizontal transmission by parasitoids. This article is protected by copyright. All rights reserved.

Tephritid fruit flies are among the most destructive horticultural pests posing risks to Australia’s multi-billion-dollar horticulture industry. Currently, there are 11 pest fruit fly species of economic concern in Australia. Of these, nine are native to this continent (Bactrocera aquilonis, B. bryoniae, B. halfordiae, B. jarvisi, B. kraussi, B. musae, B. neohumeralis, B. tryoni and Zeugodacus cucumis), while B. frauenfeldi and Ceratitis capitata are introduced. To varying degrees these species are costly to Australia’s horticulture through in-farm management, monitoring to demonstrate pest freedom, quarantine and trade restrictions, and crop losses. Here, we used a common species distribution model, Maxent, to assess climate suitability for these 11 species under baseline (1960–1990) and future climate scenarios for Australia. Projections indicate that the Wet Tropics is likely to be vulnerable to all 11 species until at least 2070, with the east coast of Australia also likely to remain vulnerable to multiple species. While the Cape York Peninsula and Northern Territory are projected to have suitable climate for numerous species, extrapolation to novel climates in these areas decreases confidence in model projections. The climate suitability of major horticulture areas currently in eastern Queensland, southern-central New South Wales and southern Victoria to these pests may increase as climate changes. By highlighting areas at risk of pest range expansion in the future our study may guide Australia’s horticulture industry in developing effective monitoring and management strategies.

Bactrocera xanthodes (Broun) (Dacinae), the Pacific fruit fly, is a major pest that is widespread in the South Pacific. It infests the fruit of 34 hosts in 20 families and is a significant impediment to horticultural market access for South Pacific countries. It is weakly responsive to the male attractant methyl eugenol (ME) and consequently is difficult to detect and control. Recently, in Australia and Bangladesh, some weakly ME-responsive species were found to be more attracted to one or more of the eugenol analogues isoeugenol, methyl-isoeugenol and dihydroeugenol. We therefore considered it worthwhile to field test the relative attractiveness of these lures to B. xanthodes. Field trials were conducted in Tonga for 9 weeks between September and November 2017. The male attractants isoeugenol, methyl-isoeugenol, dihydroeugenol and a novel eugenol analogue, 1,2-dimethoxy-4-propylbenzene, were tested in comparison to ME, cue-lure and zingerone. More than three times more male B. xanthodes were caught in methyl-isoeugenol-baited traps (mean 33.0 ± 1.8 flies/trap/day(FTD)) than in ME traps (10.7 ± 1.0 FTD) with several individual weekly methyl-isoeugenol trap clearances catching over 600 flies. Bactrocera xanthodes was also caught in 1,2-dimethoxy-4-propylbenzene traps (mean 3.1 ± 0.5 FTD), but in numbers significantly less than in ME. This is the first record of this species responding to these novel male lures. The significantly greater response of B. xanthodes to methyl-isoeugenol would make it a considerably more effective attractant for use in surveillance and control programs.

Bactrocera curvipennis (Froggatt) is a polyphagous pest fruit fly endemic to New Caledonia that is weakly attracted to the male lure cue-lure (CL). Effective male lures are important for the monitoring and management of numerous pest species of Dacinae fruit flies. However, if a species is weakly responsive to these lures its detection and control is difficult. Recently in Oceania and Asia, more attractive male lures (isoeugenol, methyl-isoeugenol, dihydroeugenol, and zingerone) were identified for several weakly CL- and methyl eugenol (ME)-responsive species. To determine if these lures may be more attractive to B. curvipennis, we field tested them in comparison to CL and ME in New Caledonia. Bactrocera curvipennis catch with isoeugenol-baited traps (mean 20.3 ± 3.0) was 15 times greater than with CL (1.3 ± 0.8) and catch with dihydroeugenol (5.7 ± 1.6) was four times greater than with CL. This is the first record of B. curvipennis responding to these lures. It was also the only species that responded to isoeugenol in this study. Bactrocera fulvifacies (Perkins) (Diptera: Tephritidae), a rarely encountered species ‘nonresponsive’ to male lures, was attracted to zingerone with its trap catch (2,574 flies) approaching that of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) at CL (2,724 flies). Another nonresponsive species, Dacus aneuvittatus (Drew) (Diptera: Tephritidae), was also trapped by zingerone-baited traps. This is the first record of these species responding to a male lure. The significantly greater response of B. curvipennis to isoeugenol would make it a considerably more effective attractant for use in surveillance and control programs.

Tephritid fruit flies are among the most destructive horticultural pests and pose risks to Australia’s multi-billion-dollar horticulture industry. Currently, there are 11 pest fruit fly species of economic concern present in various regions of Australia. Of these, nine are native to this continent (Bactrocera aquilonis, B. bryoniae, B. halfordiae, B. jarvisi, B. kraussi, B. musae, B. neohumeralis, B. tryoni and Zeugodacus cucumis), while B. frauenfeldi and Ceratitis capitata are introduced. To varying degrees these species are costly to Australia’s horticulture through in-farm management, monitoring to demonstrate pest freedom, quarantine and trade restrictions, and crop losses. Here, we used a common species distribution modelling approach, Maxent, to assess habitat suitability for these 11 species under current and future climate scenarios. These projections indicate that the Wet Tropics is likely to be vulnerable to all 11 species. The east coast of Australia will likely remain vulnerable to multiple species until at least 2070. Both the Cape York Peninsula and Northern Territory are also likely to be vulnerable, however, extrapolation to novel climates in these areas decrease confidence in model projections. The climate suitability of current major horticulture regions in north-western Australia, the Northern Territory, southern-central regions of New South Wales and southern Victoria to these pests is projected to increase as climate changes. Our study highlights areas at risk of pest range expansion in the future, to guide Australia’s horticulture industry in developing effective monitoring and management strategies.

Male fruit fly attractants, cue-lure (CL) and methyl eugenol (ME), are important in the monitoring and control of pest fruit fly species. Species respond to CL or ME but not both, and there are conflicting reports on whether combining CL (or its hydroxy analogue raspberry ketone) and ME decreases their attractiveness to different species. Fruit fly monitoring programs expend significant effort using separate CL and ME traps and avoiding lure cross-contamination, and combining the two lures in one trap would create substantial savings. To determine if combining lures has an inhibitory effect on trap catch, CL and ME wicks placed in the same Steiner trap were field tested in comparison to CL alone and ME alone in Australia and Papua New Guinea (PNG). In Australia, 24 out of 27 species trapped were significantly more attracted to CL or ME alone than the combination ME/CL lure, including the pests Bactrocera bryoniae (Tryon), B. frauenfeldi (Schiner), B. kraussi (Hardy), B. neohumeralis (Hardy), B. tryoni (Froggatt) (CL-responsive), and B. musae (Tryon) (ME-responsive). In PNG, 13 out of 16 species trapped were significantly more attracted to CL or ME alone than the ME/CL combination, including the pests B. bryoniae, B. frauenfeldi, B. neohumeralis, B. trivialis (Drew), Zeugodacus cucurbitae (Coquillett) (CL-responsive) and B. dorsalis (Hendel), B. musae, and B. umbrosa (Fabricius) (ME-responsive). This study shows that combining CL and ME in the one trap in equal parts significantly reduces catches of most species of Dacini fruit flies in Australia and PNG.

Effective male fruit fly attractants, such as cue lure (CL) and methyl eugenol (ME), are important in the monitoring and management of pest species through lure and kill techniques of trapping and male annihilation. However, some species are only weakly responsive to these lures, making their detection and control difficult. Zeugodacus diversus (Coquillett), a pest of cucurbit flowers in Asia, is weakly attracted to ME. Recently in Australia and Papua New Guinea, the eugenol analogues isoeugenol, methyl-isoeugenol, and dihydroeugenol were found to be effective attractants for species with a weak response to ME and CL, as well as several nonresponsive species. Additionally, studies from the early 1900s indicated that Z. diversus was attracted to isoeugenol. To determine if these eugenol analogues may be more effective attractants for Z. diversus, we field tested them in Bangladesh in comparison to ME, as well as CL and zingerone. Z. diversus was significantly more attracted to all three eugenol analogues than ME, with it most attracted to methyl-isoeugenol. Its attraction to methyl-isoeugenol was 49 times greater than its attraction to ME (respective means 23.58 flies/trap/day (FTD) and 0.48 FTD). Z. diversus was also consistently trapped at methyl-isoeugenol at all trap clearances including when populations were low, whereas it was only trapped at ME at 6 out of the 13 clearances. This study demonstrates that methyl-isoeugenol is a highly attractive lure for Z. diversus and would be a valuable inclusion as an attractant in monitoring and male annihilation programs.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Containing over 5,000 species, Tephritidae is a diverse fly family notorious for containing some of the world’s most destructive fruit pests, including the Mediterranean fruit fly, Oriental fruit fly, South American fruit fly, and Queensland fruit fly. As for most insects, traditional taxonomy has relied primarily on morphological characters to discriminate, define, and describe new species. This has failed to fully resolve some of the most important pest groups, especially those belonging to species complexes, leading to significant debates among the tephritid community. We argue that an integrative approach, correlating independent datasets to the same individual voucher specimens, represents the future of tephritid systematics, taxonomy, and diagnostics. This is particularly important for problematic groups of high biosecurity concern at higher risk of diagnostic confusion.

Male fruit fly attractants – cue-lure and methyl eugenol (ME) – have been used successfully for decades in the monitoring and control of species of Dacini (Dacinae) fruit flies (Bactrocera, Zeugodacus and Dacus). However, many species, including several pests, are non-responsive to these lures. Field tests of new compounds are therefore worthwhile, particularly in areas of high species diversity where multiple species attractions can provide additional information on lure function. Recent field tests of new male attractants (isoeugenol, dihydroeugenol, methyl-isoeugenol and zingerone) and food- and host-based lures (cucumber volatile blend and Cera Trap®) in Australia resulted in discoveries of lure responses for ‘non-responsive’ species. In this study, these new lures were field tested for the first time in Papua New Guinea (PNG) for attractiveness to ‘non-responsive’ species, including the guava pest Bactrocera obliqua and cucurbit pests Zeugodacus atrisetosus and Z. decipiens. Testing was conducted in the National Capital District (NCD) and Kerevat on the island province of East New Britain. Of the ‘non-responsive’ pest species, B. obliqua was trapped three times at isoeugenol and once at methyl-isoeugenol. This is the first record of B. obliqua responding to male lures. Zeugodacus decipiens was significantly attracted to Cera Trap. Five undescribed species responded to zingerone and one to the eugenol analogues. The ME-responsive B. musae and B. umbrosa responded differently to the three eugenol analogues in Kerevat and NCD, with both species responding more strongly to methyl-isoeugenol in NCD, although their response to ME was similar in both locations. Intraspecific differences in lure response were also noted between this study and that recorded previously in other countries. The cue-responsive B. frauenfeldi, B. neohumeralis and Dacus axanus were previously trapped at zingerone in Australia, and the ME-responsive B. dorsalis was trapped at zingerone in Mala

This project is revising diagnostic tools for all high-priority Dacini fruit fly species in the National Fruit Fly Strategy and their non-pest relatives including offshore and Australian endemics. This will include developing a suite of tailor-made molecular diagnostic tools which will be integrated with morphological and biological data. To facilitate this, fresh material is being collected in Australia, Asia and the Pacific using male lure traps. As the male lures cue-lure and methyl eugenol are only effective in trapping approximately 50% of all fruit fly species, other lures are needed to collect non-responsive taxa or those with a weak response to these lures. In Australia zingerone and eugenol analogues were found to be attractive to several species that had not previously been recorded at male lures and were more attractive to some cue- and ME-responsive species. Melolure was found to be a stronger attractant for several cue-responsive species. Integrating these lures into this project has been important in enabling more complete collections for diagnostic and taxonomic studies.

Bactrocera frauenfeldi (Schiner), the ‘mango fruit fly’, is a horticultural pest originating from the Papua New Guinea region. It was first detected in Australia on Cape York Peninsula in north Queensland in 1974 and had spread to Cairns by 1994 and Townsville by 1997. Bactrocera frauenfeldi has not been recorded further south since then despite its invasive potential, an absence of any controls and an abundance of hosts in southern areas. Analysis of cue-lure trapping data from 1997 to 2012 in relation to environmental variables shows that the distribution of B. frauenfeldi in Queensland correlates to locations with a minimum temperature for the coldest month >13.2°C, annual temperature range <19.3°C, mean temperature of the driest quarter >20.2°C, precipitation of the wettest month >268 mm, precipitation of the wettest quarter >697 mm, temperature seasonality <30.9°C (i.e. lower temperature variability) and areas with higher human population per square kilometre. Annual temperature range was the most important variable in predicting this species' distribution. Predictive distribution maps based on an uncorrelated subset of these variables reasonably reflected the current distribution of this species in northern Australia and predicted other areas in the world potentially at risk from invasion by this species. This analysis shows that the distribution of B. frauenfeldi in Australia is correlated to certain environmental variables that have most likely limited this species' spread southward in Queensland. This is of importance to Australian horticulture in demonstrating that B. frauenfeldi is unlikely to establish in horticultural production areas further south than Townsville.

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.