Bactrocera minax (Chinese citrus fly)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Vectors
- Plant Trade
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Bactrocera minax (Enderlein)
Preferred Common Name
- Chinese citrus fly
Other Scientific Names
- Bactrocera citri (Chen)
- Callantra minax (Enderlein)
- Dacus citri Chen
- Dacus minax (Enderlein)
- Mellesis citri Chen
- Polistomimetes minax Enderlein
- Tetradacus citri Chen
- DACUCT (Bactrocera minax)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Diptera
- Family: Tephritidae
- Genus: Bactrocera
- Species: Bactrocera minax
Notes on Taxonomy and NomenclatureTop of page B. minax belongs to subgenus Tetradacus and its name may therefore be cited as Bactrocera (Tetradacus) minax (Enderlein). Prior to the work of White and Wang (1992), some workers had erroneously listed B. citri as a synonym of B. tsuneonis and that confusion has caused some cataloguers to list B. minax and B. tsuneonis as synonyms.
DescriptionTop of page Adult
The genus Bactrocera belongs to the family Tephritidae, which is part of the superfamily Tephritoidea. In common with most species of Tephritoidea it has patterned wings, and the female has a long telescopic and pointed ovipositor; these features are hardly known outside the Tephritoidea. The family Tephritidae may also be separated from all other Diptera by the shape of the subcostal vein, which bends abruptly through a right-angle and fades to a fold before reaching the wing edge, combined with the presence of setulae along the dorsal side of vein R1. At the wing base, species of Bactrocera and Dacus have a very deep cell bm and a very long pointed extension of cell bcu (= cup). The genus Bactrocera, is separated from Dacus, by the terga (dorsal sclerites of the abdomen) not being fused into a single sclerotized plate.
B. minax belongs to subgenus Tetradacus, which lack postpronotal setae, prescutellar acrostical setae and basal scutellar setae; males have a pecten (row or comb of setae along each postero-lateral margin of tergum 3) and the posterior margin of the 5th sternite has a deep V-shaped emargination. Members of this subgenus are generally the largest members of the genus, with wing lengths of 9 mm or more.
B. minax is a predominantly orange-brown species; it has medial and lateral yellow vittae (stripes) on the scutum, including the unusual feature of lateral yellow stripes anterior to the suture (often hard to see in stained specimens). It lacks anterior supra-alar setae and the aculeus of the female (needs dissection) has a single rounded apical point.
A full description was provided by White and Elson-Harris (1994). However, the larva of B. tsuneonis remains unknown and the characters given may to a large extent also apply to that species, making larval identification unreliable.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 23 Apr 2020
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Bhutan||Present||Achterberg (1999); EPPO (2020)|
|China||Present, Localized||EPPO (2020)|
|-Guangxi||Present||Liang et al. (1993); EPPO (2020)|
|-Guizhou||Present||EPPO (2020); CABI (Undated)|
|-Hubei||Present||Liang et al. (1993); EPPO (2020); CABI (Undated);|
|-Hunan||Present||Liang et al. (1993); EPPO (2020); CABI (Undated)|
|-Jiangsu||Present||EPPO (2020); CABI (Undated)|
|-Shaanxi||Present||UK, CAB International (1991); EPPO (2020)|
|-Sichuan||Present||Liang et al. (1993); EPPO (2020); CABI (Undated);|
|-Yunnan||Present||UK, CAB International (1991); EPPO (2020)|
|India||Present, Localized||EPPO (2020)|
|-Sikkim||Present||Enderlein (1920); EPPO (2020)|
|-West Bengal||Present||UK, CAB International (1991); EPPO (2020)|
Risk of IntroductionTop of page B. minax has the potential to establish on Citrus in areas outside of Asia. The closely related B. tsuneonis was listed as an A1 quarantine pest by EPPO (OEPP/EPPO, 1983) and others at a time when the names of these two species were confused.
Hosts/Species AffectedTop of page B. minax is a specialist on Citrus and related genera of Rutaceae. It is a large powerful insect presumably adapted to oviposition through the thick skin of oranges, for example.
Host Plants and Other Plants AffectedTop of page
|Citrus aurantium (sour orange)||Rutaceae||Main|
|Citrus limon (lemon)||Rutaceae||Other|
|Citrus maxima (pummelo)||Rutaceae||Main|
|Citrus medica (citron)||Rutaceae||Other|
|Citrus reticulata (mandarin)||Rutaceae||Main|
|Citrus sinensis (navel orange)||Rutaceae||Main|
|Citrus x paradisi (grapefruit)||Rutaceae||Other|
|Fortunella x crassifolia (meiwa kumquat)||Rutaceae||Other|
|Poncirus trifoliata (Trifoliate orange)||Rutaceae||Other|
Growth StagesTop of page Fruiting stage
SymptomsTop of page The area around the oviposition puncture made by Bactrocera usually gets discoloured. Details are available for the closely related B. tsuneonis.
List of Symptoms/SignsTop of page
|Fruit / discoloration|
|Fruit / gummosis|
|Fruit / internal feeding|
|Fruit / lesions: black or brown|
|Fruit / lesions: scab or pitting|
|Fruit / obvious exit hole|
|Fruit / odour|
|Fruit / ooze|
Biology and EcologyTop of page B. minax is univoltine and and it overwinters as a puparium (Zhang, 1989); there is considerable cold tolerance in the puparium (Fan et al., 1994). Zhang (1989) noted that emergence began at the end of April in Sichuan Province, China, and before oviposition, the adults needed supplementary nutrients. Mating began 20 days after emergence, and oviposition 15 days later; the peak period for egg hatching was early September, there were three larval instars and pupation peaked in the period from the end of October to mid-November.
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Means of Movement and DispersalTop of page Adult flight and the transport of infested fruits are the major means of movement and dispersal to previously uninfested areas.
Pathway VectorsTop of page
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Fruits (inc. pods)||eggs; larvae||Yes||Pest or symptoms usually visible to the naked eye|
|Growing medium accompanying plants||pupae||Yes||Pest or symptoms usually visible to the naked eye|
|Plant parts not known to carry the pest in trade/transport|
|Stems (above ground)/Shoots/Trunks/Branches|
|True seeds (inc. grain)|
ImpactTop of page Wang et al. (1995) said 5% of oranges were attacked in an area of Guizhou, China.
Detection and InspectionTop of page Unlike most pest species of Bactrocera, the males of this species are not attracted to any known chemical lure. However, both sexes may be monitored using protein bait traps (either protein hydrolysate or protein autolysate) but these traps also collect large numbers of non-target insects; see Drew (1982) for further details.
Similarities to Other Species/ConditionsTop of page B. minax is very similar in general appearance to B. tsuneonis but differs in the absence of anterior supra-alar setae, and by the single point of the female aculeus. These features are described in the interactive key to pest species of Dacini. Lin et al. (2007) have developed a rapid molecular diagnostic technique for the identification of these two species.
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.The following general control measures for control of Bactrocera broadly apply to B. minax. When detected, it is important to gather all fallen and infested host fruits, and destroy them. Insecticidal protection is possible by using a cover or bait spray. Specific recommendations are few; spraying with trichlorphon in sugar solution before female oviposition affords satisfactory control in orchards (Zhang, 1989). Malathion is the usual choice of insecticide for fruit fly control and this is usually combined with protein hydrolysate to form a bait spray (Roessler, 1989); practical details were given by Bateman (1982). Bait sprays work on the principle that both male and female tephritids are strongly attracted to a protein source from which ammonia emanates. Bait sprays have the advantage over cover sprays in that they can be applied as a spot treatment so that the flies are attracted to the insecticide and there is minimal impact on natural enemies.
A sterile insect technique has been applied. In Guizhou, China, Wang et al. (1995) reduced attack on oranges from over 5% to around 0.1% by releasing 1,000,000 sterile males.
Consignments of fruits of Citrus and Fortunella from countries where B. minax occurs should be inspected for symptoms of infestation and those suspected should be cut open in order to look for larvae. EPPO recommends that such fruits should come from an area where B. minax does not occur, or from a place of production found free from the pest by regular inspection for 3 months before harvest. Fruits may also be treated, but specific treatment schedules have mostly not been developed for the Asiatic citrus fruit flies, since citrus is not much exported from the countries where they occur. Schedules developed for Ceratitis capitata on citrus will probably be adequate, for example, cold treatment in transit (such as 11, 12 or 14 days at 0.5, 1 or 1.5°C, respectively; USDA, 1994). Zhao et al. (1995) used gamma irradiation to as a post-harvest treatment to kill larvae in pummelo, tangerine and sweet orange.
Plants of citrus transported with roots from countries where B. minax occurs should be free from soil, or the soil should be treated against puparia. The plants should not carry fruits. Citrus plants are in any case prohibited from importation in many countries because of other quarantine pests.
ReferencesTop of page
Bateman MA, 1982. III. Chemical methods for suppression or eradication of fruit fly populations, In: Drew RAI, Hooper GHS, Bateman MA eds. Economic Fruit Flies of the South Pacific Region. 2nd edn. Brisbane, Australia: Queensland Department of Primary Industries, 115-128.
Drew RAI, 1982. Fruit fly collecting. In: Drew RAI, Hooper GHS, Bateman MA, eds. Economic Fruit Flies of the South Pacific Region, 2nd edition. Brisbane, Australia: Queensland Department of Primary Industries, 129-139.
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Ming Yue, 1985. Identification of two species of Chinese citrus flies. Plant Quarantine, 1:35-39.
Roessler Y, 1989. Control; insecticides; insecticidal bait and cover sprays. In: Robinson AS, Hooper G, eds. Fruit Flies. Their Biology, Natural Enemies and Control. World Crop Pests 3(B). Amsterdam, Netherlands: Elsevier, 329-336.
USDA, 1994. Treatment manual. Frederick, USA: USDA/APHIS.
Wang HuaSong, Hu JianGuo, Lu DaGuang, Kang Wen, Zhang HeQin, 1995. Control of Chinese citrus fly in large area by releasing irradiated sterile flies. Chinese Journal of Biological Control, 11(4):156-159; 5 ref.
Wang Xing-Jian, 1998. The fruit flies (Diptera: Tephritidae) of the East Asian region. Acta Zootaxonomica Sinica, 21(supplement):1-338.
Zhao XueQian, Fan JingAn, Xie ChengLun, Qin Zhen, Li Gang, Zhu Jun, 1995. A study of the influence of gamma irradiation (Co) on the larvae of Tetradacus citri (Chen). Journal of Southwest Agricultural University, 17(2):126-129
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Distribution MapsTop of page
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