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.
Microbiomes play vital roles in insect fitness and health and can be influenced by interactions between insects and their parasites. Many studies investigate the microbiome of free-living ...insects, whereas microbiomes of endoparasitoids and their interactions with parasitised insects are less explored. Due to their development in the constrained environment within a host, endoparasitoids are expected to have less diverse yet distinct microbiomes. We used high-throughput 16S rRNA gene amplicon sequencing to characterise the bacterial communities of
Dipterophagus daci
(Strepsiptera) and seven of its tephritid fruit fly host species
.
Bacterial communities of
D. daci
were less diverse and contained fewer taxa relative to the bacterial communities of the tephritid hosts. The strepsipteran’s microbiome was dominated by Pseudomonadota (formerly Proteobacteria) (> 96%), mainly attributed to the presence of
Wolbachia
, with few other bacterial community members, indicative of an overall less diverse microbiome in
D. daci
. In contrast, a dominance of
Wolbachia
was not found in flies parasitised by early stages of
D. daci
nor unparasitised flies
.
Yet, early stages of
D. daci
parasitisation resulted in structural changes in the bacterial communities of parasitised flies. Furthermore, parasitisation with early stages of
D. daci
with
Wolbachia
was associated with a change in the relative abundance of some bacterial taxa relative to parasitisation with early stages of
D. daci
lacking
Wolbachia
. Our study is a first comprehensive characterisation of bacterial communities in a Strepsiptera species together with the more diverse bacterial communities of its hosts and reveals effects of concealed stages of parasitisation on host bacterial communities.
Anthropogenic climate change is a major factor driving shifts in the distributions of pests and invasive species. The Queensland fruit fly, Bactrocera tryoni Froggatt (Qfly), is the most economically ...damaging insect pest of Australia's horticultural industry, and its management is a key priority for plant protection and biosecurity. Identifying the extent to which climate change may alter the distribution of suitable habitat for Qfly is important for the development and continuation of effective monitoring programs, phytosanitary measures, and management strategies. We used Maxent, a species distribution model, to map suitable habitat for Qfly under current climate, and six climate scenarios for 2030, 2050 and 2070. Our results highlight that south-western Australia, northern regions of the Northern Territory, eastern Queensland, and much of south-eastern Australia are currently suitable for Qfly. This includes southern Victoria and eastern Tasmania, which are currently free of breeding populations. There is substantial agreement across future climate scenarios that most areas currently suitable will remain so until at least 2070. Our projections provide an initial estimate of the potential exposure of Australia's horticultural industry to Qfly as climate changes, highlighting the need for long-term vigilance across southern Australia to prevent further range expansion of this species.
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.
Abstract
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 × 10
1
copies/µL and 1 × 10
3
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.
The male fruit fly attractants, cue-lure (CL) and raspberry ketone (RK), are important in pest management. These volatile phenylbutanoids occur in daciniphilous Bulbophyllum Thouar (Orchidaceae: ...Asparagales) orchids, along with zingerone (ZN) and anisyl acetone (AA). While these four compounds attract a similar range of species, their relative attractiveness to multiple species is unknown. We field tested these compounds in two fruit fly speciose locations in north Queensland, Australia (Lockhart and Cairns) for 8 wk. Of 16 species trapped in significant numbers, 14 were trapped with CL and RK, all in significantly greater numbers with CL traps than RK traps (at least in higher population locations). This included the pest species Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) (CL catches ca. 5× > RK), Bactrocera neohumeralis (Hardy) (Diptera: Tephritidae) and Bactrocera bryoniae (Tryon) (Diptera:Tephritidae) (CL catches ca. 3× > RK), and Bactrocera frauenfeldi (Schiner) (Diptera:Tephritidae) (in Cairns—CL catches ca. 1.6× > RK). Seven species were trapped with AA, and all were also caught in CL and RK traps in significantly greater numbers, with the exception of B. frauenfeldi. For this species, catches were not statistically different with CL, RK, and AA in Lockhart, and RK and AA in Cairns. Seven species were trapped with ZN, two at this lure only, and the remainder also with CL or RK but in significantly greater numbers. This is the first quantitative comparison of the relative attractiveness of CL, RK, AA, and ZN against multiple species, and supports the long-held but untested assumption that CL is broadly more attractive lure than RK.
Summary
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 parasitization. We performed the first genetic characterization of D. daci and detected D. daci in Wolbachia‐positive flies not visibly parasitized, and most but not all Wolbachia‐negative flies were D. daci‐negative, presumably reflecting polymorphism for the Wolbachia infections in D. daci. We dissected D. daci from stylopized flies and confirmed that Wolbachia infects D. daci, but also found Wolbachia in stylopized 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 parasitization 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.
Tephritid fruit flies are amongst the most significant horticultural pests globally and male chemical lures are important for monitoring and control. Zingerone has emerged as a unique male fruit fly ...lure that can attract dacine fruit flies that are weakly or non-responsive to methyl eugenol and cuelure. However, the key features of zingerone that mediate this attraction are unknown. As Jarvis's fruit fly, Bactrocera jarvisi (Tryon), is strongly attracted to zingerone, we evaluated the response of B. jarvisi to 37 zingerone analogues in a series of field trials to elucidate the functional groups involved in attraction. The most attractive analogues were alkoxy derivatives, with isopropoxy being the most attractive, followed by ethoxy and trifluoromethoxy analogues. All of the phenolic esters tested were also attractive with the response typically decreasing with increasing size of the ester. Results indicate that the carbonyl group, methoxy group, and phenol of zingerone are key sites for the attraction of B. jarvisi and identify some constraints on the range of structural modifications that can be made to zingerone without compromising attraction. These findings are important for future work in developing and optimising novel male chemical lures for fruit flies.
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.
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 Malaysia, but these species, while caught at their respective lures, were not recorded at zingerone in this study. The findings from this study have implications for quarantine monitoring for the ‘non‐responsive’ B. obliqua and Z. decipiens in Australia, highlight that there may be intraspecific variation in male lure response and provide further information on these novel male lures' activity.
PDF
