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The global invasion of Tephritidae (fruit flies) attracts a great deal of attention in the field of plant quarantine and invasion biology because of their economic importance. Predicting which one in hundreds of potential invasive fruit fly species is most likely to establish in a region presents a significant challenge, but can be facilitated using a self organising map (SOM), which is able to analyse species associations to rank large numbers of species simultaneously with an index of establishment. A global presence/absence dataset including 180 economically significant fruit fly species in 118 countries was analysed using a SOM. We compare and contrast ranked lists from six countries selected from each continent, and also show that those countries geographically close were clustered together by the SOM analysis because they have similar fruit fly assemblages. These closely clustered countries therefore represent greater threats to each other as sources of invasive fruit fly species. Finally, we indicate how this SOM method could be utilized as an initial screen to support prioritizing fruit fly species for further research into their potential to invade a region.

Azadirachtin exhibits excellent bioactivities against several hundred arthropods. However, current knowlege of its biochemical effect on B . dorsalis larvae is not deep enough. In this study, integrated LC-MS and GC-MS-based untargeted metabolomics were used to analyze the changes of endogenous metabolites and the biochemical effects of azadirachtin on B . dorsalis larvae. Azadirachtin has excellent bioactivities against B . dorsalis larvae in this study, leading to a longer developmental duration, lower survival rate, and low pupa weight. The effect of azadirachtin was investigated on a total of 22 and 13 differentially abundant metabolites in the LC–MS and GC–MS-based metabolomics results, are selected respectively. Pathway analysis indicated that 14 differentially enriched metabolic pathways, including seven influential pathways, are worthy of attention. Further integrated key metabolic pathway analysis showed that histidine metabolism, d -glutamine and d -glutamate metabolism, biotin metabolism, ascorbate and aldarate metabolism, pentose and glucuronate interconversions, and alanine, aspartate and glutamate metabolism in B . dorsalis larvae are significantly relevant pathways affected by azadirachtin. Although extrapolating the bioactivity results in this study to the practical project of B . dorsalis pest management in the field has limitations, it was found that azadirachtin has a significant effect on the primary metabolism of B . dorsalis larvae.

Abstract Bactrocera dorsalis (Hendel, 1912), a major invasive pest, survives under extreme climates through molecular and tissue-specific cold stress adaptations. In this study, we investigated the tissue-specific impacts of cold stress on the survival and molecular response of B. dorsalis. Results showed that cold stress had a significant effect on survival rates. The Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that signaling and metabolic pathways were activated by cold stress in the head and fat body during a transcriptome analysis. Under cold stress, 184 and 365 genes were differentially expressed in the head and fat body, respectively. RNA interference (RNAi)-mediated knockdown of transposon Ty3-I Gag-Pol polyprotein (Ty3-I) and Ty3-G Gag-Pol polyprotein (Ty3-G) in the head and fat body, significantly reduced the larval survival. Relative expression analysis revealed that expression of the Ty3-I and Ty3-G Gag-Pol polyprotein was greatly reduced in the head of cold treated larvae relative to controls (dsGFP) and that the expression level of Ty3-I Gag-Pol polyprotein in the fat body was not significantly reduced by cold stress. These results highlight the tissue-specific response of Ty3-I and Ty3-G Gag-Pol polyproteins in mediating cold stress responses and aid in understanding their importance in survival and stress adaptation. Additionally, the identification of important stress-responsive genes provides a foundation for the development of RNAi-based strategies for pest control using the targeted disruption of stress adaptation gene pathways for more effective control of B. dorsalis populations.

A major cause for biodiversity may be biodiversity itself. As new species form, they may create new niches for others to exploit, potentially catalyzing a chain reaction of speciation events across trophic levels. We tested for such sequential radiation in the Rhagoletis pomonella (Diptera: Tephritidae) complex, a model for sympatric speciation via host plant shifting. We report that the parasitic wasp Diachasma alloeum (Hymenoptera: Braconidae) has formed new incipient species as a result of specializing on diversifying fly hosts, including the recently derived apple-infesting race of R. pomonella. Furthermore, we show that traits that differentially adapt R. pomonella flies to their host plants have also quickly evolved and serve as ecological barriers to reproduction, isolating the wasps. Speciation therefore cascades as the effects of new niche construction move across trophic levels.

The oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae), is a widespread pest in Bangladesh. Sterile Insect Technique (SIT) offers a solution for effectively suppressing this fruit fly species. However, SIT involves mass rearing of fruit fly species in a laboratory where a standardized artificial rearing diet is crucial for ensuring uniform growth, development, and reproduction. In this study, we assessed efficacy of a new formulated gel-based meridic larval diet as well as protein and carbohydrate rich adult diets for the rearing of B. dorsalis in laboratory conditions. Proximate analysis was conducted for our formulated rearing diets to determine the content of moisture, protein, fat, carbohydrate, and ash. For our formulated diets, several key biological parameters, including egg hatching rate, pupation rate, pupal weight, adult emergence, adult growth, sex ratio, and flight capacity, were assessed. Statistical analysis using Tukey box plots revealed a significant improvement for the laboratory reared body parameters of adults while maintained in meridic diets, as compared to their wild counterparts. Adults fruit flies reared on our formulated meridic adult diets exhibited sufficient longevity, especially when compared to those provided with only water. In addition, our study presents survival analysis using non-parametric Kaplan–Meier estimator and Weibull parametric model. Our findings indicate that the formulated diets presented in this study can be effectively incorporated into B. dorsalis laboratory mass-rearing, meeting the required standard quality parameters outlined in the FAO/IAEA/USDA mass-rearing guideline of tephritid fruit flies.

Fruit flies belonging to Tephritidae family are highly destructive agricultural pests, posing a significant threat to various fruits and vegetables grown in Bangladesh. A comprehensive year-round survey was conducted at Atomic Energy Research Establishment (AERE) campus located in the central region of Bangladesh. Three types of male lures (methyl eugenol, cue-lure and zingerone) were used to detect and assess the diversity of pest fruit fly species. A total of seventeen species of Tephritidae fruit flies were detected in this survey. The Bactrocera carambolae fruit fly has been discovered for the first time in our survey area, indicating spread of its range towards the north-west region from its previous detection sites (Chattogram and Sylhet Divisions) in Bangladesh. Among the detected pest species, we identified six abundant species: Bactrocera dorsalis , Zeugodacus cucurbitae , Zeugodacus tau , Bactrocera rubigina , Bactrocera zonata , and Dacus longicornis . The most abundant species was the polyphagous fruit pest B. dorsalis , comprising 76.83% of the total captured flies. The species Z. cucurbitae was the second most abundant, representing 13.82% of the total trapped flies. The fitted curve to survey data using Gaussian mixture model revealed the existence of overlapped subgroups in the temporal population distribution of B. dorsalis and Z. cucurbitae . In addition, our statistical analysis of the six abundant Tephritidae fruit fly species revealed correlation of population dynamics with several factors including temperature, rainfall, humidity, photoperiod, and fruiting time of host plant species in the selected area.

The gut microbiome of insects directly or indirectly affects the metabolism, immune status, sensory perception and feeding behavior of its host. Here, we examine the hypothesis that in the oriental fruit fly (Bactrocera dorsalis, Diptera: Tephritidae), the presence or absence of gut symbionts affects foraging behavior and nutrient ingestion. We offered protein-starved flies, symbiotic or aposymbiotic, a choice between diets containing all amino acids or only the non-essential ones. The different diets were presented in a foraging arena as drops that varied in their size and density, creating an imbalanced foraging environment. Suppressing the microbiome resulted in significant changes of the foraging behavior of both male and female flies. Aposymbiotic flies responded faster to the diets offered in experimental arenas, spent more time feeding, ingested more drops of food, and were constrained to feed on time-consuming patches (containing small drops of food), when these offered the full complement of amino acids. We discuss these results in the context of previous studies on the effect of the gut microbiome on host behavior, and suggest that these be extended to the life history dimension.

The oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most economically important pests in the world, causing serious damage to fruit production. However, lack of genetic information on this organism is an obstacle to understanding the mechanisms behind its development and its ability to resist insecticides. Analysis of the B. dorsalis transcriptome and its expression profile data is essential to extending the genetic information resources on this species, providing a shortcut that will support studies on B. dorsalis. We performed de novo assembly of a transcriptome using short read sequencing technology (Illumina). The results generated 484,628 contigs, 70,640 scaffolds, and 49,804 unigenes. Of those unigenes, 27,455 (55.13%) matched known proteins in the NCBI database, as determined by BLAST search. Clusters of orthologous groups (COG), gene orthology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations were performed to better understand the functions of these unigenes. Genes related to insecticide resistance were analyzed in additional detail. Digital gene expression (DGE) libraries showed differences in gene expression profiles at different developmental stages (eggs, third-instar larvae, pupae, and adults). To confirm the DGE results, the expression profiles of six randomly selected genes were analyzed. This transcriptome greatly improves our genetic understanding of B. dorsalis and makes a huge number of gene sequences available for further study, including both genes of known importance and genes of unknown function. The DGE data provide comprehensive insight into gene expression profiles at different developmental stages. This facilitates the study of the role of each gene in the developmental process and in insecticide resistance.

Insect mitogenome organisation is highly conserved, yet, some insects, especially with parasitic life cycles, have rearranged mitogenomes. Furthermore, intraspecific mitochondrial diversity can be reduced by fitness-affecting bacterial endosymbionts like Wolbachia due to their maternal coinheritance with mitochondria. We have sequenced mitogenomes of the Wolbachia -infected endoparasitoid Dipterophagus daci (Strepsiptera: Halictophagidae) and four of its 22 known tephritid fruit fly host species using total genomic extracts of parasitised flies collected across > 700 km in Australia. This halictophagid mitogenome revealed extensive rearrangements relative to the four fly mitogenomes which exhibited the ancestral insect mitogenome pattern. Compared to the only four available other strepsipteran mitogenomes, the D. daci mitogenome had additional transpositions of one rRNA and two tRNA genes, and a single nucleotide frameshift deletion in nad5 requiring translational frameshifting or, alternatively, resulting in a large protein truncation. Dipterophagus daci displays an almost completely endoparasitic life cycle when compared to Strepsiptera that have maintained the ancestral state of free-living adults. Our results support the hypothesis that the transition to extreme endoparasitism evolved together with increased levels of mitogenome changes. Furthermore, intraspecific mitogenome diversity was substantially smaller in D. daci than the parasitised flies suggesting Wolbachia reduced mitochondrial diversity because of a role in D. daci fitness.

Several insect lineages, including some fruit flies, have evolved mutualistic associations with primary symbiotic bacteria. Some species of Tephritinae, the most specialized subfamily of fruit flies (Diptera, Tephritidae) harbour co-evolved, vertically transmitted and non-culturable bacterial symbionts in their midgut, known as Candidatus Stammerula spp. (Enterobacteriaceae). While such associations have previously been reported in the Palearctic and Hawaiian Archipelago, their occurrence in Australasia had not been investigated. In this study we assessed the genetic diversity of eight Australian fruit fly’s species from six genera belonging to the Tephritini tribe using mitochondrial markers (16 S rRNA and COI–tRNALeu–COII genes) and compared their bacterial diversity using the 16 S rRNA gene. We detected the presence of specific symbiotic bacteria in all sampled species. Analysis of bacterial 16 S rRNA showed that, with one exception, all Australian symbionts clustered in a well-supported monophyletic clade with Ca. Stammerula detected in Palearctic and Hawaiian Tephritini. Distinct Stammerula lineages were identified in several taxa, while two species, Trupanea prolata and Spathulina acroleuca shared identical symbiont sequences and the same host plant. Notably, Australian and Palearctic Sphenella spp. harboured closely related symbionts. The cophylogenetic analysis revealed a substantial congruence between host and symbiont tree, supporting a history of cospeciation and suggesting biogeographic links between Australasian and Palearctic taxa. Overall, the results expand the geographic knowledge of Tephritini- Ca. Stammerula association and highlight a global pattern of co-diversification.