Oriental Fruit Fly Bactrocera Dorsalis Research Articles

Possibilities of competitive displacement of Bactrocera dorsalis (Hendel) by Bactrocera zonata (Saunders) (Tephritidae: Diptera) in guava Psidium guajava ecosystem in Sudan

Oriental fruit fly (OFF) Bactrocera dorsalis and peach fruit fly (PFF) Bactrocera zonata are the most notorious pests that invaded Sudan in 2005 and 2012, respectively, causing severe losses and hindering horticultural production and exports. Prior to 2012, OFF was the most abundant fly in guava orchards in Gezira State. Monitoring fruit flies to determine species composition, seasonality, and possibilities of competitive displacement was conducted in two guava (Psidium guajava) orchards in Gezira State; Fadasi and Gezirat Elfil, using food bait attractant and rearing flies from infested fruits..Longevity and survival percentages of developmental stages of the two species were also determined. Monitoring fly populations using Torula yeast and rearing of fruit flies from guava fruits revealed that OFF and PFF were the most prevalent species in guava ecosystem at both sites. At the Fadasi site, PFF was the predominant species representing (99.3%) of the guild of the trapped flies with an infestation level of 99.6%) flies/kg of guava fruits. At G. Elfil, OFF comprised 80.8% of the trapped flies with infestation level ca 53.6% while 19.2% of trapped flies were B. zonata with 46.4% infestation level. The high percentage of trapped OFF at G. Elfil might be attributed to multi-cropping system in the area. Developmental stages of PFF were shorter than that of OFF by 9.2 days, while its survival percentage was higher than that of OFF for all developmental stages. Competitive displacement of OFF by PFF in guava orchards at Fadasi site may have occurred as a result of the mono-cropping system, short developmental period, and high survival percentage of developmental stages of PFF on guava compared to that of OFF.

Host Status of Persian Lime (Citrus latifolia Tan.) to Oriental Fruit Fly and Mediterranean Fruit Fly (Diptera: Tephritidae) in Hawai'i.

We investigated the host status of harvest-ready green Persian lime, Citrus x latifolia Tan. (Rutaceae), to Oriental fruit fly (Bactrocera dorsalis [Hendel]) and Mediterranean fruit fly (Ceratitis capitata [Wiedemann]) (Diptera: Tephritidae) using laboratory and field studies. In forced-infestation small cage exposures (using 25 × 25 × 25 cm screened cages with 50 gravid females) and large olfactometer cage tests (using 2.9 × 2.9 × 2.5 m walk-in screened cages with 100 gravid females), punctured limes were infested by Oriental fruit fly and Mediterranean fruit fly at low rates compared to papaya controls, whereas undamaged intact fruit was not infested. Field collection and packing of 45,958 commercial export-grade fruit and subsequent incubation to look for natural infestation resulted in no emergence of fruit flies. Forced infestation studies in the field using sleeve cages to enclose fruit with a high density of fruit flies (50 gravid females) on the tree also showed no infestation. Commercial export-grade Persian lime fruit should be considered a conditional nonhost for Oriental fruit fly and Mediterranean fruit fly.

Phytosanitary cold treatment of cherry tomatoes infested with Bactrocera dorsalis, Zeugodacus cucurbitae, and Zeugodacus tau (Diptera: Tephritidae).

Fruit flies attack numerous crops, including cherry tomatoes (Solanum lycopersicum var. cerasiforme). The potential presence of the immature stages of fruit fly species inside tomatoes during export hinders their international market access. Therefore, phytosanitary treatment must be performed before export to prevent fruit fly species from entering countries where they are not naturally found. We developed a phytosanitary cold disinfestation treatment protocol to eliminate oriental fruit fly (Bactrocera dorsalis Hendel), melon fly (Zeugodacus cucurbitae Coquillett), and pumpkin fruit fly (Zeugodacus tau Walker) concealed inside cherry tomatoes without causing critical damage to the fruit. We determined that the third instar of Z. cucurbitae exhibited the highest cold tolerance among the various development stages of the three fruit fly species. Thus, we performed a small-scale disinfestation test on Z. cucurbitae in two cultivars of tomato. We achieved complete disinfestation after 15 days of cold treatment at 1°C-1.5°C. The confirmatory test revealed the elimination of more than 80,000 treated third instar of Z. cucurbitae in each tomato variety. The developed phytosanitary cold treatment allows the tomatoes to retain their commercial value. This study provides a standard phytosanitary cold treatment protocol for cherry tomatoes, ensuring the disinfestation of fruit flies before their export to international markets.

Persistence of widespread moderate Spinosad resistance among wild melon fly (Zeugodacus cucurbitae) and oriental fruit fly (Bactrocera dorsalis) populations on the major Hawaiian islands.

Insecticide resistance among invasive tephritid fruit flies poses a great risk to national food security and has the potential to disrupt quarantine and eradication programs, which rely on the efficacy of Spinosad to prevent widespread establishment in North America. During 2022 to 2023 we surveyed the extent of Spinosad resistance of two key species, oriental fruit fly Bactrocera dorsalis, and melon fly Zeugodacus cucurbitae, from 20 sites across five Hawaiian Islands including Kaua'i, O'ahu, Maui, Molokai and the "Big Island" (Hawai'i). We used topical thoracic applications of eight concentrations of Spinosad ranging from 0.028 to 3.6 mg/mL to evaluate the lethal concentration (LC50 and LC99) required to kill wild-caught males. Resistance ratios (RR) were calculated by comparing the LC50 of wild flies to laboratory susceptible lines maintained in colony. Our results identified at least two new sites of concern for melon fly resistance on the Big Island, and at least four sites of concern for oriental fruit fly, all of which were located on the Big Island. At these locations RRs were >5. On O'ahu, melon fly RRs were >10. The persistence of Spinosad resistance is concerning, yet it is a reduction compared to the values reported previously and before changes to Spinosad use recommendations by local extension agents beginning in 2017. For oriental fruit fly, these RR values are the highest levels that have been detected in wild Hawai'i populations. These data suggest that expanded Spinosad reduction and replacement programs are warranted given the ongoing issues with Spinosad resistance in Hawai'i and expansion in the number of species affected. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

First report of Bactrocera dorsalis (Hendel) (Diptera, Tephritidae) on the white - fleshed dragon fruit Selenicereus undatus (Haworth) D.R. Hunt (Cactaceae) in India

The oriental fruit fly Bactrocera dorsalis (Hendel) has been reported on the white fleshed dragon fruit Selenicereus undatus (Haworth) D.R.Hunt for the first time in India. Symptoms of infestation and the duration of all life stages were observed. Females laid eggs just beneath the mature fruit skin. The tissue surrounding the egg mass turned light yellow. Oviposition punctures were visible on the fruit rind and the feeding of the maggots led to decay of internal contents, foul smell and the fruit turned in to a discolored semi liquid mass. Full grown maggots exited the fruit and entered a period of inactivity before pupation in moist soil. The egg, maggot and pupal stages lasted for 1.6± 0.40, 8.0 ± 0.40 and 8.0 ± 0.31 days, respectively under laboratory conditions. Adult longevity was 9.6 ± 0.5 days in the case of females and 6.4 ± 0.50 days for males.

Identification of antennal alternative splicing by combining genome and full-length transcriptome analysis in Bactrocera dorsalis.

Alternative splicing is an essential post-transcriptional regulatory mechanism that diversifies gene function by generating multiple protein isoforms from a single gene and act as a crucial role in insect environmental adaptation. Olfaction, a key sense for insect adaptation, relies heavily on the antennae, which are the primary olfactory organs expressing most of the olfactory genes. Despite the extensive annotation of olfactory genes within insect antennal tissues facilitated by high-throughput sequencing technology advancements, systematic analyses of alternative splicing are still relatively less. In this study, we focused on the oriental fruit fly (Bactrocera dorsalis), a significant pest of fruit crops. We performed a detailed analysis of alternative splicing in its antennae by utilizing the full-length transcriptome of its antennal tissue and the insect's genome. The results revealed 8600 non-redundant full-length transcripts identified in the oriental fruit fly antennal full-length transcriptome, spanning 4,145 gene loci. Over 40% of these loci exhibited multiple isoforms. Among these, 161 genes showed sex-biased isoform switching, involving seven different types of alternative splicing. Notably, events involving alternative transcription start sites (ATSS) and alternative transcription termination sites (ATTS) were the most common. Of all the genes undergoing ATSS and ATTS alternative splicing between male and female, 32 genes were alternatively spliced in protein coding regions, potentially affecting protein function. These genes were categorized based on the length of the sex-biased isoforms, with the highest difference in isoform fraction (dIF) associated with the ATSS type, including genes such as BdorABCA13, BdorCAT2, and BdorTSN3. Additionally, transcription factor binding sites for doublesex were identified upstream of both BdorABCA13 and BdorCAT2. Besides being expressed in the antennal tissues, BdorABCA13 and BdorCAT2 are also expressed in the mouthparts, legs, and genitalia of both female and male adults, suggesting their functional diversity. This study reveals alternative splicing events in the antennae of Bactrophora dorsalis from two aspects: odorant receptor genes and other types of genes expressed in the antennae. This study not only provides a research foundation for understanding the regulation of gene function by alternative splicing in the oriental fruit fly but also offers new insights for utilizing olfaction-based behavioral manipulation techniques to manage this pest.

CRISPR/Cas9 Ribo nucleoprotein complex‐mediated editing of the OBP13 gene affected the response of male Bactrocera dorsalis (Diptera: Tephritidae) to methyl eugenol

AbstractThe oriental fruit fly (Bactrocera dorsalis) is an exceptionally hazardous pest that can cause up to 100% loss. Male annihilation using male attractant methyl eugenol (ME) is the most adopted control measure of this insect. The molecular process underlying this perception of insects remains unexplored. In this study, we focus on gene functionality of odorant‐binding protein 13 (OBP13) in ME perception by knockout using CRISPR/Cas9 mediated embryonic editing through microinjection. The electrophysiological study of mutant flies through electroantennogram has shown highly depressed ME perception and further the genetic‐level mutational confirmation stating that OBP13 is a major OBP involved in ME perception. The molecular docking of OBP13 with ME revealed the predicted key interactions involved, thus providing more scope in targeting gene editing and in engineering ME substitutes.

Distribution analysis of TRH in Bactrocera dorsalis using a CRISPR/Cas9-mediated reporter knock-in strain.

Although the study of many genes and their protein products is limited by the availability of high-quality antibodies, this problem could be solved by fusing a tag/reporter to an endogenous gene using a gene-editing approach. The type II bacterial CRISPR/Cas system has been demonstrated to be an efficient gene-targeting technology for many insects, including the oriental fruit fly Bactrocera dorsalis. However, knocking in, an important editing method of the CRISPR/Cas9 system, has lagged in its application in insects. Here, we describe a highly efficient homology-directed genome editing system for B. dorsalis that incorporates coinjection of embryos with Cas9 protein, guide RNA and a short single-stranded oligodeoxynucleotide donor. This one-step procedure generates flies carrying V5 tag (42 bp) in the BdorTRH gene. In insects, as in other invertebrates and in vertebrates, the neuronal tryptophan hydroxylase (TRH) gene encodes the rate-limiting enzyme for serotonin biosynthesis in the central nervous system. Using V5 monoclonal antibody, the distribution of TRH in B. dorsalis at different developmental stages was uncovered. Our results will facilitate the generation of insects carrying precise DNA inserts in endogenous genes and will lay foundation for the investigation of the neural mechanisms underlying the serotonin-mediated behaviour of B. dorsalis.

The role of farming systems in the adoption of pest management practices: the case of the oriental fruit fly Bactrocera dorsalis in mango orchards in Senegal

Description of the suject. In Africa, pest pressure has led researchers, policymakers, and international development stakeholders to develop and disseminate innovative pest management strategies. However, farmers reject some pest management strategies due to economic constraints, agronomic problems, or incompatibilities with their strategies, knowledge bases, and visions of desirable change. Objectives. In this paper, we study the pest management practices employed by mango producers from different farming systems against the fruit fly Bactrocera dorsalis, as well as the factors determining the level of engagement of these producers in managing this pest. Method. We surveyed 304 Senegalese mango growers affected by the invasive fruit fly Bactrocera dorsalis to understand which farming systems’ features could explain the adoption level of fruit fly management tools through multivariate data analysis. Results. Three types of farming systems characterized by a coherent set of varietal choices, orchard management, harvest practices, commercial outlets, and fruit fly management practices are identified: (1) Intensive farming systems supplying the export market with the variety Kent and using a large set of orchard management tools and harvest practices to eliminate fruit flies, (2) Extensive farming systems supplying various varieties of mangoes with a dominance of Kent to both export and domestic markets, with access to fruit fly management tools from public services, (3) Gathering farming systems characterized by zero-input, high varietal diversity, difficult market access, non-selective harvest practices, and fruit fly management rarely practiced. Conclusions. The farming systems form a gradient of increasing use of fruit fly management tools and inputs, access to extension services, and export market orientation. Their coexistence in the same territories significantly contributes to the inefficiency of the control measures against Bactrocera dorsalis. Our results support the premise that in Africa, the adoption of pest management tools is more deeply integrated into the practices of certain producers compared to others, due to internal and external factors influencing the operation.

The nitrogen-dependent GABA pathway of tomato provides resistance to a globally invasive fruit fly.

The primary metabolism of plants, which is mediated by nitrogen, is closely related to the defense response to insect herbivores. An experimental system was established to examine how nitrogen mediated tomato resistance to an insect herbivore, the oriental fruit fly (Bactrocera dorsalis). All tomatoes were randomly assigned to the suitable nitrogen (control, CK) treatment, nitrogen excess (NE) treatment and nitrogen deficiency (ND) treatment. We found that nitrogen excess significantly increased the aboveground biomass of tomato and increased the pupal biomass of B. dorsalis. Metabolome analysis showed that nitrogen excess promoted the biosynthesis of amino acids in healthy fruits, including γ-aminobutyric acid (GABA), arginine and asparagine. GABA was not a differential metabolite induced by injury by B. dorsalis under nitrogen excess, but it was significantly induced in infested fruits at appropriate nitrogen levels. GABA supplementation not only increased the aboveground biomass of plants but also improved the defensive response of tomato. The biosynthesis of GABA in tomato is a resistance response to feeding by B. dorsalis in appropriate nitrogen, whereas nitrogen excess facilitates the pupal weight of B. dorsalis by inhibiting synthesis of the GABA pathway. This study concluded that excess nitrogen inhibits tomato defenses in plant-insect interactions by inhibiting GABA synthesis, answering some unresolved questions about the nitrogen-dependent GABA resistance pathway to herbivores.

Population mixing mediates the intestinal flora composition and facilitates invasiveness in a globally invasive fruit fly

BackgroundChanges in population heterozygosity and genetic diversity play important roles in mediating life history traits of organisms; these changes often lead to phenotypic evolution in offspring, which become superior to their parents. In the present study, we examined phenotypic differentiation, the intestinal microbiome composition, and metabolism shift in the oriental fruit fly (Bactrocera dorsalis) by comparing an inbred (monophyletic) original population and an outbred (mixed) invasive population.ResultsThe results showed that the outbred population of B. dorsalis had significantly higher biomass, adult longevity, and fecundity than the inbred population. Additionally, intestinal microflora analysis revealed that both Diutina rugosa and Komagataeibacter saccharivorans were significantly enriched in the outbred population with higher genetic heterozygosity. D. rugosa enrichment altered amino acid metabolism in the intestinal tract, and supplementing essential amino acids (e.g. histidine and glutamine) in the diet led to an increase in pupal weight of the outbred population. Additionally, transcriptome analysis revealed that the HSPA1S gene was significantly downregulated in the outbred population. HSPA1S was involved in activation of the JNK-MAPK pathway through negative regulation, caused the upregulation of juvenile hormone (JH), and led to an increase in biomass in the outbred flies.ConclusionIn conclusion, the outbred population had an altered intestinal microbe composition, mediating metabolism and transcriptional regulation, leading to phenotypic differentiation; this may be a potential mechanism driving the global invasion of B. dorsalis. Thus, multiple introductions could lead to invasiveness enhancement in B. dorsalis through population mixing, providing preliminary evidence that changes in the intestinal microbiome can promote biological invasion.1rGLpfiTdGk3QvEMFY5kHbVideo

Response of some mango-infesting fruit flies to aqueous solutions of the basil plant Ocimum tenuiflorum L

IntroductionHorticulture is an important sub-sector for many African countries. Tephritid fruit flies continue to cause serious direct and indirect damage to the sub-sector. The male annihilation technique (MAT) using methyl eugenol (ME) is among the most revered techniques in fruit fly management. However, ME-based lures are only available to some farmers in Africa. Several basils of the genus Ocimum produce ME.MethodsIn laboratory experiments, we used a dual choice olfactometer to assess the attraction of adult oriental fruit fly Bactrocera dorsalis to intact plants, 100 µL commercial methyl eugenol (ME) (positive control), 10 mg/mL of O. tenuiflorum aqueous extract (Otae), and a negative control (blank). Large arena experiments were conducted to compare the responses of four fruit fly species of economic importance in Africa to Otae-baited traps.ResultsIn dual choice olfactometer assay, more B. dorsalis males (78.6%) than females (23.8%) were attracted to Otae. Most B. dorsalis males were attracted to the positive control (90.5%) and 10 mg/mL Otae (88.5%) compared to the whole plant (84.0%). In large arena experiments, Otae attracted the most B. dorsalis males (47.7%), followed by Zeugodacus cucurbitae males (25.1%), while males of Ceratitis species were the least attracted. The analysis of headspace volatiles from aerial plants, Otae and essential oil using gas chromatography-mass spectrometry detected 97 compounds. The intact plant without flowers, intact plant with flowers, Otae, and the O. tenuiflorum essential oil contributed 76, 62, 33 and 28 compounds, respectively. ME comprised the top three most abundant compounds, especially in the essential oil.DiscussionOur study confirms the potential of O. tenuiflorum as a source of ME for tephritid fruit fly integrated management in Africa. Otae, a readily available alternative to commercial ME, can be used to develop fruit fly-baited traps, particularly for smallholder farmers.

Herbivore induced fruit volatiles guide the solitary tephritid endoparasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae) in selecting an oviposition substrate.

Oviposition in a generalist parasitoid is a complex process that involves interactions among its host, host plant, and spatiotemporal environment. Our study was aimed at exploring the ability of a generalist parasitic wasp, Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae), in perceiving odor cues from its host insect [Oriental fruit fly Bactrocera dorsalis (Hendel, Diptera: Tephritidae)] in infested mango fruits. A series of experiments involving behavioral and electrophysiological studies suggest that D. longicaudata is able to distinguish host infested fruit volatiles from uninfested. Additionally, we found that D. longicaudata can distinguish between high and low-level infestations using specific cues emanating from fruits. Coupled gas chromatography-electroantennographic detection (GC-EAD) and gas chromatography-mass spectrometry (GC-MS) analysis of infested mango fruit head space volatiles identified compounds such as ethyl butanoate, ethyl 3-hydroxybutyrate, β-myrcene, trans-β-ocimene, allo-ocimene, ethyl octanoate, ethyl-α-toulate, β-elemene, β-caryophyllene, humulene, caryophyllene oxide, ethyl dodecanoate, ethyl hexadecanoate, 2-furancarboxylic acid, 3-hydroxy-2-methyl-4-pyrone, and phenethyl alcohol emanated from three different host treatments with different levels of larval infestation which elicited antennal responses in D. longicaudata. We suggest that these cues might play a significant role in attracting D. longicaudata in the field.

ChIP-seq profiling of H3K4me3 and H3K27me3 in an invasive insect, Bactrocera dorsalis.

Introduction: While it has been suggested that histone modifications can facilitate animal responses to rapidly changing environments, few studies have profiled whole-genome histone modification patterns in invasive species, leaving the regulatory landscape of histone modifications in invasive species unclear. Methods: Here, we screen genome-wide patterns of two important histone modifications, trimethylated Histone H3 Lysine 4 (H3K4me3) and trimethylated Histone H3 Lysine 27 (H3K27me3), in adult thorax muscles of a notorious invasive pest, the Oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), using Chromatin Immunoprecipitation with high-throughput sequencing (ChIP-seq). Results: We identified promoters featured by the occupancy of H3K4me3, H3K27me3 or bivalent histone modifications that were respectively annotated with unique genes key to muscle development and structure maintenance. In addition, we found H3K27me3 occupied the entire body of genes, where the average enrichment was almost constant. Transcriptomic analysis indicated that H3K4me3 is associated with active gene transcription, and H3K27me3 is mostly associated with transcriptional repression. Importantly, we identified genes and putative motifs modified by distinct histone modification patterns that may possibly regulate flight activity. Discussion: These findings provide the first evidence of histone modification signature in B. dorsalis, and will be useful for future studies of epigenetic signature in other invasive insect species.

Two odorant receptors regulate 1-octen-3-ol induced oviposition behavior in the oriental fruit fly

The oriental fruit fly Bactrocera dorsalis (Hendel) is a notorious pest of fruit crops. Gravid females locate suitable oviposition sites by detecting host plant volatiles. Here, we demonstrate that 1-octen-3-ol, a volatile from mango, guides the oviposition behavior of female flies. Two odorant receptors (BdorOR7a-6 and BdorOR13a) are identified as key receptors for 1-octen-3-ol perception by qPCR analysis, heterologous expression in Xenopus laevis oocytes and HEK 293 cells followed by in vitro binding assays, as well as CRISPR/Cas9 genome editing in B. dorsalis. Molecular docking and site-directed mutagenesis are used to determine major binding sites for 1-octen-3-ol. Our results demonstrate the potential of 1-octen-3-ol to attract gravid females and molecular mechanism of its perception in B. dorsalis. BdorOR7a-6 and BdorOR13a can therefore be used as molecular targets for the development of female attractants. Furthermore, our site-directed mutagenesis data will facilitate the chemical engineering of 1-octen-3-ol to generate more efficient attractants.

Response of the braconid parasitoid Diachasmimorpha longicaudata (Ashmead) to fruits infested by oriental fruit fly, Bactrocera dorsalis (Hendel)

Biological control is an increasingly employed method in the management of tephritid pests because it is ecologically benign and target specific. The parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) is considered an effective biological control agent of tephritid pests, but there are few studies on its behavioral responses to the local host types. This information is necessary for the success of the post-release establishment of the parasitoid. The parasitoid’s behavior on oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) infested (1 and 4d old) and uninfested fruits were assessed to understand the efficacy and preference of D. longicaudata for different host fruits. The guava was considered reference fruit to compare with banana, carambola and apple. In olfactory bioassays, the parasitoid preferred banana and guava over apple and carambola, and guava that had been infested for a longer period of time. In no-choice and dual-choice bioassays, the parasitism rate, sex ratio, and fertility were compared and in dual-choice bioassays, the parasitoid exhibited significant differences of the above parameters in guava-banana and guava-carambola but not in the guava-apple trial. In the no-choice bioassays, nothing differs substantially between guava and other fruits except the parasitism rate of guava and banana which was significantly greater in guava. This study will help to understand the post-release behavior of the parasitoid to implement the integrated pest management programs of the oriental fruit fly.

Effects of Diet Composition on the Life-History Traits of Bactrocera Dorsalis (Hendel) (Diptera: Tephritidae)

Nutrient acquisition at the larval stage has significant impacts on the development, body weight, and fecundity of fruit flies. In this study, we examined the effects of diet composition on the life-history traits of the oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). We reared the flies on four larval diets, namely three artificial diets, which had the main ingredients of sugar, brewer’s yeast, and preservatives; and one fruit-based diet, which had the main contents of ground guava, brewer’s yeast, and preservatives. The three artificial diets had varied yeast-to-sugar ratios (Y:S) of 5:1 in the protein-rich diet, 1.67:1 in the standard diet, and 1:3 in the sugar-rich diet. Differences in development time, pupal weight, adult weight, and fecundity of B. dorsalis were investigated. It was found that the development times of fruit flies on the protein-rich and fruit-based diets were shorter than those on the sugar-rich and standard diets. Pupae and adults in the fruit-based and standard diets were heavier than those from the protein-rich and sugar-rich diets. There was a strong effect of diet on the per-day fecundity whereby the flies in the fruit-based diet had the highest per-day fecundity, while the lowest per-day fecundity was in the sugar-rich diet. The per-day fecundity of the fruit flies on the standard and sugar-rich diets increased gradually from day 1 to day 15, while it decreased in the protein-rich and fruit-based diets.

Genomes of the cosmopolitan fruit pest Bactrocera dorsalis (Diptera: Tephritidae) reveal its global invasion history and thermal adaptation

IntroductionThe oriental fruit fly Bactrocera dorsalis is one of the most destructive agricultural pests worldwide, with highly debated species delimitation, origin, and global spread routes. ObjectivesOur study intended to (i) resolve the taxonomic uncertainties between B. dorsalis and B. carambolae, (ii) reveal the population structure and global invasion routes of B. dorsalis across Asia, Africa, and Oceania, and (iii) identify genomic regions that are responsible for the thermal adaptation of B. dorsalis. MethodsBased on a high-quality chromosome-level reference genome assembly, we explored the population relationship using a genome-scale single nucleotide polymorphism dataset generated from the resequencing data of 487 B. dorsalis genomes and 25 B. carambolae genomes. Genome-wide association studies and silencing using RNA interference were used to identify and verify the candidate genes associated with extreme thermal stress. ResultsWe showed that B. dorsalis originates from the Southern India region with three independent invasion and spread routes worldwide: (i) from Northern India to Northern Southeast Asia, then to Southern Southeast Asia; (ii) from Northern India to Northern Southeast Asian, then to China and Hawaii; and (iii) from Southern India toward the African mainland, then to Madagascar, which is mainly facilitated by human activities including trade and immigration. Twenty-seven genes were identified by a genome-wide association study to be associated with 11 temperature bioclimatic variables. The Cyp6a9 gene may enhance the thermal adaptation of B. dorsalis and thus boost its invasion, which tended to be upregulated at a hardening temperature of 38 °C. Functional verification using RNA interference silencing against Cyp6a9, led to the specific decrease in Cyp6a9 expression, reducing the survival rate of dsRNA-feeding larvae exposed to extreme thermal stress of 45 °C after heat hardening treatments in B. dorsalis. ConclusionThis study provides insights into the evolutionary history and genetic basis of temperature adaptation in B. dorsalis.

Early infestation volatile biomarkers of fruit fly Bactrocera dorsalis (Hendel) ovipositional activity in mango (Mangifera indica L.)

Infestation of agricultural commodities by insect pests results in significant economic, import and export, food safety, and invasive insect introduction issues for growers, consumers, and inspectors. The Oriental fruit fly (Bactrocera dorsalis) is considered a highly invasive insect pest with populations reported in more than 60 countries, with prevalent distributions in Asia and Africa. B. dorsalis is phytophagous with a host range encompassing hundreds of fruits and vegetables. Damage to the fruit or vegetable is inflicted through oviposition and subsequent larval feeding resulting in spoilage. Early detection of insect pest infestations is a critical component for ensuring food safety as well as controlling introduction and spread of invasive insects. However, detection of ovipositional activity and early larval development is visually difficult, thus rapid and non-destructive detection often relies on odors associated with infestation. We investigated the odors of mangoes (Mangifera indica L.) infested with B. dorsalis and compared the volatile profiles of infested mangoes to non-infested and mechanically damaged mangoes 24 h post-infestation. GC-MS and multivariate analyses provided the identification of eleven compounds unique to infested mangoes compared to mechanically damaged or non-infested fruit. Results indicated compositional and quantitative differentiation of volatile profiles among treatments for detection of infested fruit at quality checks or points of commerce.

Study on natural enemy composition and effectiveness to control pupa and adult of Oriental fruit fly (Bactrocera dorsalis) in star apple (Chrysophyllum cainito) using entomopathogenic fungi

Study on natural enemy composition and effectiveness to control pupae and adult of Oriental fruit fly (Bactrocera dorsalis) damage on star apple using entomopathogenic fungi conducted from August 2020 to August 2021 at Southern Horticultural Research Institute and star apple orchards in Chau Thanh district, Tien Giang province. The results research on natural enemy composition of fruit flies at 10 star apple orchards recorded that there were nine natural enemy species such as Paecilomyces lilacinus, big-headed ant (Pheidole megacephala), fire ant (Solenopsis invicta), and parasitoid wasp (Diachasmimorpha longicaudata) appeared commonly with the frequency of 32.20%, 37.14%, 39.28%, and 48.00%, respectively. Followed by black earwig (Chelisoches morio), jumping spider (Plexippus paykulli), Metarhizium sp. and weaver ant (Oecophylla smaragdina) occurred less commonly with a frequency of 7.86%, 12.86%, 15.40%, and 20.00%, respectively. Beauveria sp. was very rarely with a frequency of 3.40%. Experimentally evaluating the ability to control B. dorsalis pupae and adults by entomopathogenic fungi indicated that P. lilacinus, Metarhizium sp., and TKS - BTMET (Metarhizium sp. + Beauveria sp. + Paecilomyces sp.) product were equally effective to control fruit fly adults with effectiveness of 79.12%, 69.22%, and 66.30%, respectively.