- 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 neohumeralis (Hardy)
Other Scientific Names
- Chaetodacus humeralis Perkins
- Chaetodacus tryoni var. sarcocephali Tryon
- Dacus neohumeralis Hardy
- Dacus tryoni var. neohumeralis Hardy
Local Common Names
- Australia: lesser Queensland fruit fly
- BCTRNE (Bactrocera neohumeralis)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Diptera
- Family: Tephritidae
- Genus: Bactrocera
- Species: Bactrocera neohumeralis
Notes on Taxonomy and NomenclatureTop of page B. neohumeralis was originally described as Dacus humeralis, but that is a junior homonym to an African species called Dacus humeralis. Consequently, Hardy proposed the replacement name of Dacus neohumeralis. It is now placed in the subgenus Bactrocera of the genus Bactrocera and so its presently accepted name may optionally be cited as Bactrocera (Bactrocera) neohumeralis.
DescriptionTop of page Egg
The eggs of B. oleae are described in detail by Margaritis (1985), and those of other species are probably very similar. Size, 0.8 mm long, 0.2 mm wide, with the micropyle protruding slightly at the anterior end. The chorion is reticulate (requires scanning electron microscope examination). White to yellow-white in colour.
Tha larvae are 7-9.5 mm long. Their features are similar to other species in the region (for example, B. tryoni), and identification is therefore a specialist task. A detailed description is given by White and Elson-Harris (1994).
The puparium is barrel-shaped with most larval features being unrecognizable, with the exception of the anterior and posterior spiracles which are little changed by pupariation. White to yellow-brown in colour. Size is approximately 60-80% the length of the larva.
The genus Bactrocera belongs to the family Tephritidae, which is part of the superfamily Tephritoidea. As with most species of Tephritoidea, B. neohumeralis 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 presence of setulae along the dorsal side of vein R1, and the shape of the subcostal vein, which bends abruptly through a right-angle and fades to a fold before reaching the wing edge. At the wing base, Bactrocera and Dacus species 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.
As with most species in or close to the subgenus Bactrocera, the scutum has both anterior supra-alar setae and prescutellar acrostichal setae; there are two setae (apical pair) on the margin of the scutellum. The males have a deep V-shaped notch in the fifth sternite and a pecten (comb of setae) on each side of the third abdominal tergite.
Within the subgenus Bactrocera, B. neohumeralis belongs to a species group known as the B. tryoni species group (see key by Drew, 1989), which can be identified by the costal band colouration being extended basally to include the two basal costal cells (cells bc and c). In this group cell c is also unusual completely covered in microtrichiae, and the scutum is red-brown. Within the B. tryoni species group, B. neohumeralis can be recognized by its entirely dark postpronotal lobesm, which are the same colour as the scutum.
For a species level identification see White and Hancock (1997) or Drew (1989).
DistributionTop of page The distribution of B. neohumeralis is mapped by Drew (1982a). In Queensland, Australia, it is found in areas where the annual rainfall exceeds 760 mm (Drew, 1982a).
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.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Australia||Present||Present based on regional distribution.|
|-New South Wales||Restricted distribution||Hancock et al., 2000|
|-Queensland||Restricted distribution||Hancock et al., 2000|
|Papua New Guinea||Present||Tenakanai, 1997|
Risk of IntroductionTop of page Although B. neohumeralis is generally not regarded as being such a serious pest as B. tryoni (perhaps because it gets misidentified as B. tryoni), this species is found in a similar geographic and host fruit range, indicating that it too poses a serious risk to climatically suitable areas elsewhere. In New Zealand, rapid diagnostic techniques for detection are being developed (Armstrong et al., 1997).
HabitatTop of page Rainforest and areas where suitable hosts are cultivated.
Hosts/Species AffectedTop of page B. neohumeralis is a highly polyphagous species, with a host range similar to that of B. tryoni. The data presented in the host range table are derived from a recent host catalogue by Hancock et al. (2000). Major hosts include Psidium guajava, Psidium cattleianum (wild guava, little economic use), Coffea arabica (but causes no damage) and Terminalia catappa (little economic use).
Host Plants and Other Plants AffectedTop of page
Growth StagesTop of page Fruiting stage
SymptomsTop of page Fruit which have been attacked by B. neohumeralis usually show signs of oviposition punctures around which necrosis may occur.
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|
|Whole plant / plant dead; dieback|
Biology and EcologyTop of page The eggs of Bactrocera species are laid below the skin of the host fruit. These usually hatch within a day and the larvae feed for 10-35 days, depending on the season. There are three larval instars. Pupariation occurs in the soil under the host plant for 7-30 days. Adults occur throughout the year and begin mating after approximately 1-2 weeks, and may live up to 1-3 months depending on the temperature (Christenson and Foote, 1960).
Most Bactrocera species (whose behaviour has been observed) mate at dusk, including the very closely related B. tryoni, but B. neohumeralis mates at midday (Smith, 1979).
Natural enemiesTop of page
Notes on Natural EnemiesTop of page Predation of larvae as a result of vertebrates eating infested fruit and predation of puparia in the soil (for example, by ants), are generally regarded as major causes of fruit fly mortality (White and Elson-Harris, 1994). Recent surveys in the South Pacific have indicated that levels of larval parasitism are low, generally less than 10% (Allwood, 1997). Wharton (1999) has recently described a new species of Braconid from B. neohumeralis but it is almost certainly also attacked by a similar range of species to B. tryoni. The adults are also attacked by Stylops species (Drew and Allwood, 1985).
Means of Movement and DispersalTop of page Adult flight and the transport of infested fruit are the major means of movement and dispersal of this pest to new areas.
Pathway VectorsTop of page
|Aircraft||With fruit cargo||Yes|
|Clothing, footwear and possessions||Fruit in case or handbag.||Yes|
|Containers and packaging - wood||Of fruit cargo.||Yes|
|Land vehicles||Lorries, with fruit cargo.||Yes|
|Fruit in post.||Yes|
|Ship structures above the water line||With fruit cargo||Yes|
|Soil, sand and gravel||Risk of puparia in soil.||Yes|
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 B. neohumeralis is a major pest of commercial fruit crops in Queensland, Australia, and in some crops it occurs in equal abundance to B. tryoni (Drew, 1982a).
Detection and InspectionTop of page
The males of this species are attracted to a cue lure which is usually mixed with an insecticide and used as a bait in a trap based on the Steiner trap (White and Elson-Harris, 1994). However, both sexes may be monitored using protein bait traps (either protein hydrolysate or protein autolysate) (Drew, 1982b). Flies may also be attracted to coloured sticky traps, and bright yellow traps appear to be preferred (Hill and Hooper, 1984). Field monitoring is largely carried out using traps within the areas of infestation. However, there is evidence that some fruit flies have different host preferences in different parts of their range, and host fruit surveys should also be considered as part of the monitoring process.
Many countries that are free of Bactrocera species, such as the USA (California and Florida) and New Zealand, maintain a grid of methyl eugenol (a male attractant for many other species) and cue lure traps in high-risk areas (for example, ports and airports). These traps may also be placed within other regions with a potential climate for infestation.
Fruit which are grown locally or samples of fruit imports, should be inspected for puncture marks and any associated necrosis. Suspect fruit should be cut open and checked for larvae. Larval identification is difficult, mature larvae should be transferred to sawdust (or a similar dry medium) to allow pupariation. Upon emergence, adult flies must be fed with sugar and water for several days to allow hardening and full colour to develop, before they can be identified.
Similarities to Other Species/ConditionsTop of page The B. tryoni species group (see Morphology Section) also includes B. aquilonis in northern areas of Australia and B. tryoni, which has a very similar distribution to B. neohumeralis. However, these species both have yellow postpronota.
Prevention and ControlTop of page
When detected, it is important to gather all fallen and infected host fruits, and destroy them. Baited traps should be continuously used to monitor the population size and spread. One of the most effective control techniques against fruit flies is to wrap the fruit, either in newspaper, paper bags or polythene sleeves. This is a simple physical barrier to oviposition but it must be applied well before the fruit is attacked. Early harvesting is also an effective control, because very few Bactrocera species attack the fruit prior to ripening.
Although cover sprays of the entire crop are sometimes used, bait sprays are both more economical and more environmentally acceptable. A bait spray consists of a suitable insecticide (for example, malathion), which is mixed with a protein bait (Roessler, 1989); practical details are given by Bateman (1982). Both male and female fruit flies are attracted to protein sources which emanate ammonia, and so insecticides can be applied to just a few spots in an orchard and the flies will be attracted to these spots. The protein most widely used is hydrolysed protein, but some supplies of this are acid hydrolysed which are highly phytotoxic. Smith and Nannan (1988) have developed a system using autolysed protein. In Tonga this has been developed into a very effective commercial product derived from brewery waste (Heimoana et al., 1997).
Many countries, such as the USA, forbid the import of susceptible fruit without a strict post-harvest treatment having been applied by the exporter. This may involve fumigation, heat treatment (hot vapour or hot water), cold treatments or insecticidal dipping (Armstrong and Couey, 1989; Armstrong, 1997). Heat treatment tends to reduce the shelf life of most fruits, and so the most effective method of regulatory control is to restrict imports of a given fruit to areas free of fruit fly attack.
ReferencesTop of page
Allwood AJ, 1997. Control strategies for fruit flies (family Tephritidae) in the South Pacific, In: Allwood AJ, Drew RAI, eds. Management of Fruit Flies in the Pacific. A Regional Symposium, Nadi, Fiji. ACIAR Proceedings, 76: 171-182.
Armstrong JW, 1997. Quarantine treatment options for fruit fly host commodities for Pacific island countries. In: Allwood AJ, Drew RAI, eds. Management of Fruit Flies in the Pacific. A Regional Symposium, Nadi, Fiji. ACIAR Proceedings, 76: 222-224.
Armstrong JW, Couey HM, 1989. Control; fruit disinfestation; fumigation, heat and cold. In: Robinson AS, Hooper G, eds. Fruit Flies; their Biology, Natural Enemies and Control. World Crop Pests. Amsterdam, Netherlands: Elsevier, 3(B):411-424.
Armstrong KF, Cameron CM, Frampton ER, 1997. Fruit fly (Diptera: Tephritidae) species identification: a rapid molecular diagnostic technique for quarantine application. Bulletin of Entomological Research, 87(2):111-118; 33 ref.
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.
Christenson LD, Foote RH, 1960. Biology of fruit flies. Annual Review of Entomology, 5:171-192.
Drew RAI, 1982. I. Taxonomy, 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,1-97.
Drew RAI, 1982. I. Taxonomy, In: Drew RAI, Hooper, GHS, Bateman MA, eds. Economic Fruit Flies of the South Pacific Region. 2nd ed. Brisbane, Australia: Queensland Department of Primary Industries, 1-97.
Drew RAI, 1982. IV. Fruit fly collecting. In: Drew RAI, Hooper GHS, Bateman MA, eds. Economic fruit flies of the South Pacific Region, ed. 2. Brisbane, Australia: Queensland Department of Primary Industries, 129-139.
Hancock DL, Hamacek EL, Lloyd AC, Elson-Harris MM, 2000. The distribution and host plants of fruit flies (Diptera: Tephritidae) in Australia. Department of Primary Industries, Queensland, Information Series Q199067: 1-75.
Heimoana V, Nemeye P, Langi T, Allwood AJ, 1997. Assessment of protein bait sprays for the control of fruit flies in chilli and capsicum crops in Tonga, In: Allwood AJ, Drew RAI, eds. Management of Fruit Flies in the Pacific. A Regional Symposium, Nadi, Fiji. ACIAR Proceedings, 76: 179-182.
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.
Tenakanai D, 1997, Fruit fly fauna in Papua New Guinea, In: Allwood AJ, Drew RAI, eds. Management of Fruit Flies in the Pacific. A Regional Symposium, Nadi, Fiji. ACIAR Proceedings, 76:87-94.
Wharton RA, 1999. A review of the Old World genus Fopius Wharton (Hymenoptera: Braconidae: Opiinae), with description of two new species reared from fruit-infesting Tephritidae (Diptera). Journal of Hymenoptera Research, 8(1):48-64; 33 ref.
Distribution MapsTop of page
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