Bactrocera dorsalis species complex

Taxonomy

This tool follows the monophyletic 12-species definition of the Bactrocera dorsalis complex of Doorenweerd et al. (2023b)Doorenweerd et al. (2023b):
Doorenweerd C, San Jose M, Geib S, Barr N, Rubinoff D, 2023. Genomic data reveal new species and the limits of mtDNA barcode diagnostics to contain a global pest species complex (Diptera: Tephritidae: Dacinae). Systematic Entomology: syen.12616. https://doi.org/10.1111/syen.12616, with as addition B. caryeae and B. verbascifoliae—which were not sampled in the Doorenweerd et al. (2023b)Doorenweerd et al. (2023b):
Doorenweerd C, San Jose M, Geib S, Barr N, Rubinoff D, 2023. Genomic data reveal new species and the limits of mtDNA barcode diagnostics to contain a global pest species complex (Diptera: Tephritidae: Dacinae). Systematic Entomology: syen.12616. https://doi.org/10.1111/syen.12616 study but published COI data suggests a very close relationship of B. caryeae with the B. kandiensis, and of B. verbascifoliae with B. dorsalis (Asokan et al. 2011Asokan et al. 2011:
Asokan R, Rebijith KB, Singh SK, Sidhu AS, Siddharthan S, Karanth PraveenK, Ellango R, Ramamurthy VV, 2011. Molecular Identification and Phylogeny of Bactrocera Species (Diptera: Tephritidae). Florida Entomologist 94: 1026–1035. https://doi.org/10.1653/024.094.0441). Species currently included in the B. dorsalis complex in this tool:

Valid name: Bactrocera (Bactrocera) dorsalis (Hendel, 1912)
Preferred common name: Oriental fruit fly

Valid name: Bactrocera (Bactrocera) carambolae Drew & Hancock, 1994
Preferred common name: carambola fruit fly

Valid name: Bactrocera (Bactrocera) musae (Tryon, 1927)
Preferred common name: banana fruit fly

Valid name: Bactrocera (Bactrocera) borneoensis Doorenweerd & San Jose, 2023
Valid name: Bactrocera (Bactrocera) incognita Doorenweerd & San Jose, 2023
Valid name: Bactrocera (Bactrocera) cacuminata (Hering, 1941)
Valid name: Bactrocera (Bactrocera) verbascifoliae Drew & Hancock, 1994
Valid name: Bactrocera (Bactrocera) caryeae (Kapoor, 1971)
Valid name: Bactrocera (Bactrocera) parafroggatti Drew & Romig, 2001
Valid name: Bactrocera (Bactrocera) pallida (Perkins & May, 1949)
Valid name: Bactrocera (Bactrocera) commensurata Drew & Romig, 2013
Valid name: Bactrocera (Bactrocera) occipitalis (Bezzi, 1919)
Valid name: Bactrocera (Bactrocera) kandiensis Drew & Hancock, 1994
Valid name: Bactrocera (Bactrocera) raiensis Drew & Hancock, 1994

Morphology-based identification

Based on morphology alone there are many species outside the 14-species complex that are superficially similar to B. dorsalis; some species that are commonly confused include B. thailandica and B. rubigina (cue lure attracted non-pest species), and B. ochroma (a category D pest distinguished by lighter sternite plates). Including lure attraction information and molecular data can greatly improve the identification reliability, or at least narrow the selection of candidate species down to the 14-species complex. Within the complex, a confident identification based on morphology alone is possible for B. cacuminata, B. parafroggatti, B. musae, and B. kandiensis.

Molecular identification

COI sequence data can be used to identify a specimen as belonging to the 13-species B. dorsalis complex as a whole, and within the complex it can be used to identify B. borneoensis, B. cacuminata, B. parafroggatti, B. pallida, B. commensurata, and B. musae to species-level. Bactrocera carambolae can be identified by a single SNP in the EF1-alpha gene, or using a length polymorphism of ITS-1 when COI has narrowed the selection to B. dorsalis and B. carambolae (see Leblanc et al. 2019Leblanc et al. 2019:
Leblanc L, Hossain MA, Doorenweerd C, Khan SA, Momen M, Jose MS, Rubinoff D, 2019. Six years of fruit fly surveys in Bangladesh: a new species, 33 new country records and discovery of the highly invasive Bactrocera carambolae (Diptera, Tephritidae). Zookeys 876: 87–109. https://doi.org/10.3897/zookeys.876.38096). ITS-1 can also be used to distinguish B. occipitalis from B. dorsalis (Barr et al. 2018). Due to introgression of the mitochondrial DNA, genomic data is required for a confident identification of B. dorsalis, B. incognita, B. carambolae, B. occipitalis, and B. raiensis. See Doorenweerd et al. (2023b)Doorenweerd et al. (2023b):
Doorenweerd C, San Jose M, Geib S, Barr N, Rubinoff D, 2023. Genomic data reveal new species and the limits of mtDNA barcode diagnostics to contain a global pest species complex (Diptera: Tephritidae: Dacinae). Systematic Entomology: syen.12616. https://doi.org/10.1111/syen.12616 and San Jose et al. (2023)San Jose et al. (2023):
San Jose M, Doorenweerd C, Geib S, Barr N, Dupuis JR, Leblanc L, Kauwe A, Morris KY, Rubinoff D (2023) Interspecific gene flow obscures phylogenetic relationships in an important insect pest species complex. Molecular Phylogenetics and Evolution 188: 107892. for further details.

Distribution

The Bactrocera dorsalis complex is native to Southeast Asia. Bactrocera dorsalis has spread across the entire continent of Africa in less than a decade in the early 2000s, has since reached parts of southern Europe (Nugnes et al. 2018Nugnes et al. 2018:
Nugnes F, Russo E, Viggiani G, Bernardo U, 2018. First record of an invasive fruit fly belonging to Bactrocera dorsalis complex (Diptera: Tephritidae) in Europe. Insects 9: 1–11. https://doi.org/10.3390/insects9040182), and continues to expand north in Southeast Asia (Wan et al. 2011Wan et al. 2011:
Wan X, Nardi F, Zhang B, Liu Y, 2011. The Oriental fruit fly, Bactrocera dorsalis, in China: Origin and gradual inland range expansion associated with population growth. PLoS ONE 6. https://doi.org/10.1371/journal.pone.0025238). Bactrocera carambolae is found in part of the distribution of B. dorsalis in Southeast Asia, but has invaded the Guyanas, making it the only species of Dacini in South America. Molecular evidence revealed that B. raiensis has commonly been confused with B. dorsalis and has also invaded Africa (Doorenweerd et al. 2023bDoorenweerd et al. 2023b:
Doorenweerd C, San Jose M, Geib S, Barr N, Rubinoff D, 2023. Genomic data reveal new species and the limits of mtDNA barcode diagnostics to contain a global pest species complex (Diptera: Tephritidae: Dacinae). Systematic Entomology: syen.12616. https://doi.org/10.1111/syen.12616), its pest status likely needs to be revised. For further distribution maps see San Jose et al. (2023)San Jose et al. (2023):
San Jose M, Doorenweerd C, Geib S, Barr N, Dupuis JR, Leblanc L, Kauwe A, Morris KY, Rubinoff D (2023) Interspecific gene flow obscures phylogenetic relationships in an important insect pest species complex. Molecular Phylogenetics and Evolution 188: 107892., for many species the exact distributions remain unclear due to their taxonomic confusion.

Further information

Bactrocera dorsalis and B. carambolae are listed as "category A" pests in Vargas et al. (2015)Vargas et al. (2015):
Vargas RI, Pinero JC, Leblanc L, 2015. An overview of pest species of Bactrocera fruit flies (Diptera: Tephritidae) and the integration of biopesticides with other biological approaches for their management with a focus on the pacific region. Insects 6: 297–318. https://doi.org/10.3390/insects6020297. A category A pest is defined as "widespread invasive polyphagous generalists or highly destructive specialists that have become established outside of their native range".

Bactrocera caryeae, B. occipitalis, B. kandiensis, and B. musae are listed as "category B" polyphagous pests in Vargas et al. (2015)Vargas et al. (2015):
Vargas RI, Pinero JC, Leblanc L, 2015. An overview of pest species of Bactrocera fruit flies (Diptera: Tephritidae) and the integration of biopesticides with other biological approaches for their management with a focus on the pacific region. Insects 6: 297–318. https://doi.org/10.3390/insects6020297. A category B pest is there defined as "polyphagous fruit pests or destructive specialists more restricted in distribution, but at elevated risk of spreading to new locations".

Bactrocera incognita and B. borneoensis were described in 2023 and have an unclear pest status and host ranges.

Overall, the taxonomic confusion in the complex has severely compromised the distribution and ecological knowledge, and subsequent pest status assessments, of the individual species.