Dacine Fruit Flies Research Articles

Towards a better future for DNA barcoding: Evaluating monophyly- and distance-based species identification using COI gene fragments of Dacini fruit flies.

The utility of a universal DNA 'barcode' fragment (658 base pairs of the Cytochrome C Oxidase I [COI] gene) has been established as a useful tool for species identification, and widely criticized as one for understanding the evolutionary history of a group. Large amounts of COI sequence data have been produced that hold promise for rapid species identification, for example, for biosecurity. The fruit fly tribe Dacini holds about a thousand species, of which 80 are pests of economic concern. We generated a COI reference library for 265 species of Dacini containing 5601 sequences that span most of the COI gene using circular consensus sequencing. We compared distance metrics versus monophyly assessments for species identification and although we found a 'soft' barcode gap around 2% pairwise distance, the exceptions to this rule dictate that a monophyly assessment is the only reliable method for species identification. We found that all fragments regularly used for Dacini fruit fly identification >450 base pairs long provide similar resolution. 11.3% of the species in our dataset were non-monophyletic in a COI tree, which is mostly due to species complexes. We conclude with recommendations for the future generation and use of COI libraries. We revise the generic assignment of Dacus transversus stat. rev. Hardy 1982, and Dacus perpusillus stat. rev. Drew 1971 and we establish Dacus maculipterus White 1998 syn. nov. as a junior synonym of Dacus satanas Liang etal. 1993.

A review on natural phenylbutanoid attractants: Occurrence, distribution, and role in nature, especially in relation to Dacini fruit fly behavior and pollination.

The natural occurrence, distribution (within a plant) and roles of four phenylbutanoid compounds (anisyl acetone, cue-lure, raspberry ketone and zingerone) are elucidated for the Asia-Pacific and Oceania regions. These phenylbutanoids may act individually or in combination to attract true fruit fly males belonging to a tribe Dacini of subfamily Dacinae (Diptera: Tepritidae). Of special interest are the mutualistic interactions between the Dacini fruit fly males and the tropical daciniphilous (attracting exclusively Dacini fruit flies) orchids - leading to cross pollination for the orchids and enchanced mating success for the flies. When offered to male flies, anisyl acetone and cue-lure are generally converted to raspberry ketone. Upon consumption, raspberry ketone and zingerone are individually sequestered in the male rectal (pheromonal) gland unchanged. Attracted male flies readily imbibe the phenylbutanoid(s) in the floral synomone to compliment the endogenously synthesized male sex pheromonal components - to enhance attraction of conspecific females during courtship as well as attract conspecific males to form 'leks'. The phenylbutanoid(s) may also act as an allomone to deter vertebrate predators, especially geckos, besides possessing antimicrobial and antioxidant activities. Cue-lure, raspberry ketone and zingerone are important attractants/lures used in pest surveillance and mass trapping under the integrated pest management (IPM) program against quarantine Dacini fruit fly pest species, particularly Bactrocera tryoni and Zeugodacus cucurbitae.

A checklist of the dacine fruit flies (Diptera, Tephritidae, Dacinae) of Mozambique

Here we present a checklist of all records of dacine fruit flies (Diptera: Tephritidae: Dacinae) from Mozambique, based on verified specimen records in natural history collections and literature records. In total, 57 Dacinae species are recorded from Mozambique, of which only one is considered endemic. This relatively low species diversity compared to other African countries appears to be related to incomplete sampling. For each species the localities from which it was recorded are given (including geocoordinates), or a general distribution is provided. The checklist is discussed briefly in terms of species richness, endemism and geographic distribution.

Development of a cost-effective, morphology-preserving method for DNA isolation from bulk invertebrate trap catches: Tephritid fruit flies as an exemplar.

Insect identification and preservation of voucher specimens is integral to pest diagnostic and surveillance activities; yet bulk-trapped insects are a diagnostic challenge due to high catch numbers and the susceptibility of samples to environmental damage. Many insect trap catches rely on examination of morphological characters for species identifications, which is a time consuming and highly skilled task, hence there is a need for more efficient molecular approaches. Many bulk DNA extraction methods require destructive sampling of specimens, resulting in damaged, or fully destroyed, voucher specimens. We developed an inexpensive, rapid, bulk DNA isolation method that preserves specimens as pinned vouchers to a standard that allows for post-extraction morphological examination and inclusion in insect reference collections. Our protocol was validated using a group of insects that are time-consuming to identify when trapped in large numbers-the dacine fruit flies (Diptera: Tephritidae: Dacinae). In developing our method, we evaluated existing protocols against the following criteria: effect on morphology; suitability for large trap catches; cost; ease of handling; and application to downstream molecular diagnostic analyses such as real-time PCR and metabarcoding. We found that the optimum method for rapid isolation of DNA extraction was immersing flies in a NaOH:TE buffer at 75°C for 10 minutes, without the need for proteinase K or detergents. This HotSOAK method produced sufficient high-quality DNA whilst preserving morphological characters suitable for species-level identification with up to 20,000 flies in a sample. The lysates performed well in down-stream analyses such as loop-mediated isothermal amplification (LAMP) and real-time PCR applications, while for metabarcoding PCR the lysate required an additional column purification step. Development of this method is a key step required for upscaling our capacity to accurately detect insects captured in bulk traps, whether for biodiversity, biosecurity, or pest management objectives.

Floral synomone components of fruit fly-attracting orchids, Bulbophyllum sinapis and B. hahlianum, in Papua New Guinea

Papua New Guinea (PNG) is known as the center of diversification of the largest orchid genus Bulbophyllum . In order to understand the ecological adaptation mechanisms in two closely related Dacini fruit fly-attracting orchids species, B. sinapis and B. hahlianum, their floral synomone components were examined. Flowers of B. sinapis attract males of various agricultural pest fruit fly species, such as Bactrocera musae and Ba. umbrosa, with methyl eugenol (a phenylpropanoid). However, flowers of B. hahlianum, attract fruit fly males belonging to a more diverse group of cue-lure-responsive species, namely, Ba. frauenfeldi, Ba. bryoniae and Zeugodacus cucurbitae with a mixture of phenylbutanoids including anisyl acetone (AA), raspberry ketone (RK) and zingerone (ZN). Contents of the volatiles in floral parts of both species were quantified. The highest contents of floral volatiles were detected in the lateral sepals of both the Bulbophyllum species. Attractant activity of synthetic AA, RK and ZN was examined in a local habitat in East New Britain. Furthermore, male flies attracted to B. hahlianum were found to sequester RK in the body tissues in varying quantities, which suggests its role as a sex pheromonal component to attract conspecific females as in the case of other Dacini fruit fly species through pharmacophagous acquisition of the orchid synomone. • Papua New Guinean orchids attract males of Dacini fruit flies with floral volatiles (83). • Floral synomone possesses either phenylpropanoid or phenylbutanoid male attractants (83). • Consume floral volatiles used by male flies as sex pheromone to attract females (80). • Biochemical and phylogenetic relationships of daciniphilous orchids are examined (80).

Population fluctuations of economically important male Dacine fruit flies (Diptera: Tephritidae) at Savar, Dhaka

Population fluctuations of male fruit flies were monitored using Hawaii traps baited with parakairomone lures (methyl eugenol, cue lure and zingerone) for one year (Nov 2017–Oct 2018) at ten different sites at Savar, Dhaka, Bangladesh. A total of 73,188 flies were collected, which belong to 16 species and dominated by Bactrocera dorsalis (56.99%), Zeugodacus cucurbitae (22.90%), Z. tau (14.30%) and B. rubigina (3.40%). B. zonata, B. correcta and Dacus longicornis were collected in much smaller numbers. Population fluctuations of B. dorsalis, with peaks in July, was positively correlated with minimum temperature (r=0.68), maximum temperature (r=0.50), rainfall (r=0.86) and host availability. It was similar to B. zonata and B. rubigina. Z. cucurbitae population peaked in March and have no clear correlation with maximum temperatures and rainfall. Captures of Z. tau and D. longicornis were inversely related to rainfall, having abundance peaks in the dry winter months.

A comprehensive phylogeny helps clarify the evolutionary history of host breadth and lure response in the Australian Dacini fruit flies (Diptera: Tephritidae)

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. Methyl eugenol response has arisen on multiple, independent occasions. The evolution of host breadth exhibited a weaker signal; yet, basal groups were more likely to be host specialists. Both the evolution of lure response and host fruit use provide predictive information for the outbreak management of understudied pest fruit flies for which direct inference of these features may be lacking. Our results, which parallel those of earlier research into the closely-related African Dacus spp., demonstrate how geographically focussed taxon coverage allows Dacini phylogenetics to more explicitly test evolutionary hypotheses, thereby progressing our understanding of the evolution of this highly diverse and recently-radiated group of flies.

Functional characterization of an olfactory receptor in the Oriental fruit fly, Bactrocera dorsalis, that responds to eugenol and isoeugenol.

Most insects utilize a diverse array of olfactory cues for host finding and reproduction behaviors. Males of several Dacini fruit fly species (Tephritidae) are selectively attracted to certain phytochemicals to acquire sex pheromone precursors. Despite the importance of olfaction, only a limited number of olfactory receptors (ORs) in Dacini fruit flies have been characterized. In this study, I focused on the OR94b-2 subfamily, because a clade consisting of these homologs was distinctly localized from other OR clades in a constructed phylogenetic tree. To deorphanize the ORs, I used plant essential oils to screen ligands. Using heterologous expression in Xenopus oocytes, I analyzed the functional properties of BdorOR94b-2 and ZcucOR94b-2 from the Oriental fruit fly, Bactrocera dorsalis, and the melon fruit fly, Zeugodacus cucurbitae, respectively. I found that cinnamon leaf oil evoked responses in oocytes expressing BdorOR94b-2 and the corresponding co-receptor BdorORCO. Gas chromatography-mass spectrometry analysis indicated that eugenol is a major component of cinnamon leaf oil. In accordance with the response to cinnamon leaf oil containing eugenol, BdorOR94b-2/BdorORCO revealed a weak but significant response to eugenol. BdorOR94b-2/BdorORCO also responded to isoeugenol, but not to other related aromatic semiochemicals such as known male-specific attractants and sex pheromones. In contrast, ZcucOR94b-2/ZcucORCO did not respond to any of the phenolic compounds tested, including eugenol analogs. Therefore, BdorOR94b-2/BdorORCO is narrowly tuned to eugenol analogs, whereas ZcucOR94b-2/ZcucORCO likely binds to other compound(s).

New country records, annotated checklist and key to the dacine fruit flies (Diptera: Tephritidae: Dacinae: Dacini) of Bangladesh

New country records, annotated checklist and key to the dacine fruit flies (Diptera: Tephritidae: Dacinae: Dacini) of Bangladesh

Novel lures and COI sequences reveal cryptic new species of Bactrocera fruit flies in the Solomon Islands (Diptera, Tephritidae, Dacini).

Results from a snap-shot survey of Dacine fruit flies carried out on three of the Solomon Islands in April 2018 are reported. Using traps baited with the male lures cue-lure, methyl eugenol, and zingerone, 30 of the 48 species previously known to occur in the Solomon Islands were collected. Six species are newly described here: Bactroceraallodistinctasp. nov., B.geminosimulatasp. nov., B.kolombangaraesp. nov., B.quasienochrasp. nov., B.tsatsiaisp. nov., and B.vargasisp. nov., all authored by Leblanc & Doorenweerd. An illustrated key to the 54 species now known to be present in the country is provided.

Spatio-temporal distribution of sexual calling behaviour in domesticated, sterile and wild Queensland fruit fly males under field cage conditions.

The sterile insect technique (SIT) is used in Australia to contain and eradicate outbreaks of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) in fruit-fly-free regions, and to manage populations in some endemic regions. To assess the likely impact of SIT on wild B. tryoni populations it is important to assess the colocation and synchrony of male calling between sterile and wild flies. We observed the location and timing of calling behaviours of marked mass-reared (fertile and sterile) and wild B. tryoni males in walk-in field cages. We found that wild males called further from the canopy centre than mass-reared (fertile or sterile) males. Mass-reared (fertile or sterile) males called earlier in the evening than wild males and, consequently, mass-reared males called when temperature and light intensity were higher than when wild males called. Male calling is a prerequisite to mating among dacine fruit flies. Therefore, our observations of spatio-temporal divergence in male calling behaviour may lead to assortative mating between mass-reared and wild B. tryoni in SIT applications. The importance of these spatio-temporal differences warrants further inquiry, with particular focus on how environmental conditions modify calling behaviour and avenues to ameliorate differences between sterile and wild flies. © 2021 Society of Chemical Industry.

Recent Advancements in Studies on Chemosensory Mechanisms Underlying Detection of Semiochemicals in Dacini Fruit Flies of Economic Importance (Diptera: Tephritidae).

Simple SummaryChemical information, among various environmental cues, is the most important factor for insect survival and reproduction. Insects usually rely on pheromone signals, including sex, aggregation, and alarm pheromones, in conspecific communications. For phytophagous insects, plant semiochemicals associated with insect–plant interactions profoundly affect insect behavior and physiology. Therefore, elucidation of the mechanisms underlying the perception of various chemical signals is essential to understand the adaptation of insects to their surrounding environment. Dacini fruit flies are interesting models to investigate chemosensory mechanisms because they utilize various chemical cues, such as floral fragrances in mutualistic relationships, volatiles released from host fruits, and sex pheromones in mating behaviors. Since many Dacini species are serious pests, novel insights into chemosensory mechanisms not only contribute to understanding basic principles of chemoreception, but also provide cues for the development of more effective agents for pest control. Herein, we review current knowledge on chemosensory mechanisms and related topics in Dacini fruit flies from various aspects of chemical ecology, physiology, neuroscience, and molecular biology. We also discuss future perspectives based on recent advancements in these studies.Dacini fruit flies mainly contain two genera, Bactrocera and Zeugodacus, and include many important pests of fruits and vegetables. Their life cycle is affected by various environmental cues. Among them, multiple characteristic semiochemicals have remarkable effects on their reproductive and host-finding behaviors. Notably, floral fragrances released from so-called fruit fly orchids strongly attract males of several Dacini fruit fly species. Focusing on the strong attraction of male flies to particular chemicals, natural and synthetic lures have been used for pest management. Thus, the perception of semiochemicals is important to understand environmental adaptation in Dacini fruit flies. Since next-generation sequencers are available, a large number of chemosensory-related genes have been identified in Dacini fruit flies, as well as other insects. Furthermore, recent studies have succeeded in the functional analyses of olfactory receptors in response to semiochemicals. Thus, characterization of molecular components required for chemoreception is under way. However, the mechanisms underlying chemoreception remain largely unknown. This paper reviews recent findings on peripheral mechanisms in the perception of odors in Dacini fruit flies, describing related studies in other dipteran species, mainly the model insect Drosophila melanogaster. Based on the review, important themes for future research have also been discussed.

Evaluation of Solid Lure Plugs and Insecticide Dispensers on Capturing Dacine Fruit Flies and Non-target Insects

The present study investigated the efficacy of solid male lures viz., cuelure (C-L), methyl eugenol (ME) and tri-med lure (TML) formulated with insecticide for the capture of Tephritid fruit flies in three different green areas of Bangladesh. We also evaluated non-target attraction effects to traps baited with these male lures. Traps were placed at nine locations in each of three experimental fields of Savar, Dhaka, Bangladesh during May-September, 2015. The experimental areas were i. Atomic Ene

The Dacini fruit fly fauna of Sulawesi fits Lydekker's line but also supports Wallacea as a biogeographic region (Diptera, Tephritidae).

Although there is scientific consensus on most of the major biogeographic regions in the world, the demarcation of the area connecting Southeast Asia with Australia and Oceania remains debated. Two candidate boundaries potentially explain faunistic diversity patterns in the regions: Lydekker’s and Wallace’s lines. The islands in between both ‘lines’ are jointly termed Wallacea, with Sulawesi as the largest landmass. We surveyed Dacini fruit flies (Tephritidae: Dacinae) in Sulawesi between 2016 and 2019 using traps baited with male lures, resulting in 4,517 collected flies. We identified all specimens to species level, which adds 15 new species records to the island, bringing the total number of Dacini species in Sulawesi to 83. The biogeographic affinity of species in the updated checklist reveals a strong connection with former ‘Sunda’ (41% of species); validating Lydekker’s line, but also a high level of endemism (47% of species), confirming the uniqueness of Wallacea as a biogeographic region. We further describe a new species, Bactrocera (Bactrocera) niogreta Doorenweerd, sp. nov. and discuss the taxonomy of several interesting species.

Male-lure type, lure dosage, and fly age at feeding all influence male mating success in Jarvis\u2019 fruit fly

Males of certain Dacini fruit flies are strongly attracted to, and feed upon, plant secondary compounds such as methyl eugenol, raspberry ketone and zingerone. The consumed lure is generally found to induce physiological and behavioural changes that enhance the mating performance of lure-fed males. Male Bactrocera jarvisi respond strongly to zingerone from a young age, but only weakly respond to raspberry ketone. We hypothesized that this selective lure-response would be reflected in the physiological importance of the lure to the fly. We found that zingerone feeding by young males resulted in significantly greater mating success in competitive mating trials with lure-deprived flies, but the mating advantage was lost in older males. Lure dosage had a significant effect on the duration of the mating advantage, for example when fed 20 µg of zingerone, the advantage lasted only 1 day post-feeding, but when fed of 50 µg zingerone the advantage lasted 7 days. Raspberry ketone feeding did not confer any mating advantage to males except at one dosage (50 µg) for 1 day after feeding. When given a choice, B. jarvisi females preferred to mate with zingerone-fed versus to raspberry ketone-fed males. This study revealed lure, dosage and age of fly at time of lure administration are all important factors for maximising lure-enhanced fruit fly mating performance. These findings contribute to a better theoretical understanding of the evolution of fruit fly-lure interactions and may help improve fruit fly pest management via the Sterile Insect Technique through semiochemical-mediated enhancement of sterile male mating performance.

Insecticidal activity of ring-fluorinated benzyl acetone analogs in Queensland fruit fly, a softer class of insecticides

Insecticides used to control fruit fly pests have been implicated in negative effects on natural enemies, human health and the environment. As potential ‘softer’ insecticides, natural compounds such as essential oils and their constituents have received increased attention as insecticide candidates. Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt), is the most economically damaging fruit fly species in Australia. Cuelure and melolure are plant-based attractants of males in Q-fly and many other dacine fruit flies and are structurally similar to benzyl acetone. We hypothesized that fluorination of benzyl acetone would introduce toxicity that could be exploited for insecticidal applications. Toxicity to Q-fly of nine fluorinated analogs of benzyl acetone as well as the known attractants cuelure and melolure was investigated. LC50 and LC90 values of the compounds were obtained using a surface-film assay method. Fluorination at the meta and/or para-position of benzene ring was found to increase toxicity to both Q-fly sexes. We further examined toxicity and short-range attraction to Q-fly using traps in outdoor cages. The nine fluorinated analogs of benzyl acetone were all highly toxic to male Q-flies, whereas cuelure and melolure were not. Some analogs were attractive to male Q-flies. None of the nine analogs, cuelure or melolure had an inhibitory effect on the proliferation of BEAS-2B human bronchial epithelial cells, suggesting very low or negligible mammalian toxicity. Fluorinated analogs of benzyl acetone have potential as new toxicants for Q-fly, and likely other insects, and some may also have attractive properties for cuelure-responding fruit flies.

Systematic Modification of Zingerone Reveals Structural Requirements for Attraction of Jarvis\u2019s Fruit Fly

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.

Floral fragrances in two closely related fruit fly orchids, Bulbophyllum hortorum and B. macranthoides (Orchidaceae): assortments of phenylbutanoids to attract tephritid fruit fly males

Floral chemical components are important cues used by plants to attract pollinators. One outstanding case is “fruit fly orchids” in the genus of Bulbophyllum to attract their pollinators by releasing characteristic fragrances. Dacini fruit flies are main or exclusive pollinators which are strongly attracted to certain natural chemicals, either methyl eugenol (ME: a phenylpropanoid) or raspberry ketone (RK: a phenylbutanoid). Furthermore, zingerone (ZN: a phenylbutanoid) has been characterized as the attractant for both ME- and RK-sensitive fruit fly species. In the present study, we examined chemical profiles of two closely related Bulbophyllum orchids—B. hortorum, and B. macranthoides subsp. tollenoniferum—distributed in Papua New Guinea and the Southeast Asian countries, respectively. We first observed that RK-sensitive flies were attracted to these orchids by ex situ cultivation in Penang, Malaysia. These Bulbophyllum orchids contained RK and/or ZN as their main floral components. Other than these attractants, multiple phenylbutanoids including potential attractants for RK-sensitive species were identified from these orchids. Therefore, we examined attractiveness of potential phenylbutanoid attractants to an RK-sensitive melon fly, Zeugodacus cucurbitae, using laboratory-reared flies. Furthermore, we analyzed molecular phylogenetic relationships among phenylpropanoid- or phenylbutanoid-producing orchids to see a relation between chemical profiles and phylogenetic classification in the related species.

An Overview of Indian Dacine Fruit Flies (Diptera: Tephritidae: Dacinae: Dacini)

Fruit flies belonging to tribe Dacini are pertinent pests of horticultural crops in Southeast Asia, Sub-Saharan Africa and Australasian Oceanian region. They pose enormous threats to fruit and vegetable production throughout the world, causing both quantitative and qualitative losses. Ninety two species of dacine fruit flies (28 endemic, 30.43% endemism) belonging to three genera, viz. Bactrocera Macquart (51 species, 17 endemic, 33.33% endemism), Dacus Fabricius (10 species, 3 endemic, 30.0% endemism), and Zeugodacus Hendel (31 species, 8 endemic, 25.80% endemism), and 19 subgenera have been listed from India. Of these, nine endemic species, viz. Bactrocera (Bactrocera) andamanensis, B. (B.) blairiae, B. (B.) curtivitta, B. (B.) patula, B. (B.) ranganathi, B. (Calodacus) harrietensis, Dacus (Mellesis) insulosus, Zeugodacus (Zeugodacus) fuscoalatus, Z. (Z.) havelockiae are known only from Andaman & Nicobar Islands. The current understanding of the morphology of the tribe, together with data on their biology, habitat associations, and distribution combine presents a picture of the phylogenetic relationships within the group. Besides, the knowledge of biology and behaviour of dacine species suggests that there is a close relationship between the fly species and their host plants which involves adult's feeding, host recognition, courtship and mating, oviposition, larval feeding and bacteria associations. In the present paper notes on subgeneric classification of Dacini, their distribution, endemism, relative occurrence of different taxa, phylogeny, host associations, pest status, male lures and bacterial associations have been added.

Functional characterization of olfactory receptors in three Dacini fruit flies (Diptera: Tephritidae) that respond to 1-nonanol analogs as components in the rectal glands.

Dacini fruit flies (Tephritidae: Diptera), including destructive pest species, are strongly affected in their reproductive behaviors by semiochemicals. Notably, male lures have been developed for pest management e.g., aromatic compounds for the Oriental fruit fly Bactrocera dorsalis and the melon fruit fly Zeugodacus cucurbitae; terpenic α-ionone analogs for the solanaceous fruit fly, B. latifrons. Other than those specific male attractants, 1-nonanol analogs have been noticed as major aliphatic components in the male rectal gland, which is considered as a secretory organ of male sex pheromones. Although multiple semiochemicals associated with the life cycle of Dacini fruit flies have been identified, their behavioral role(s) and chemosensory mechanisms by which the perception occurs have not been fully elucidated. In this study, we conducted RNA sequencing analysis of the chemosensory organs of B. latifrons and Z. cucurbitae to identify the genes coding for chemosensory receptors. Because the skeletons of male attractants are different among Dacini fruit fly species, we analyzed phylogenetic relationships of candidate olfactory receptors (ORs) among the three species. We found that the OR phylogeny reflects the taxonomic relationships of the three species. We further characterized functional properties of OR74a in the three Dacini species to the 1-nonanol analogs related to components in the rectal glands. The three OR74a homologs responded to 1-nonanol, but their sensitivities differed from each other. The OR74a homologs identified from B. dorsalis and Z. cucurbitae responded significantly to 6-oxo-1-nonanol, but not to 1,3-nonanediol and nonyl acetate, indicating similar binding properties of the homologous ORs.