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Transient incursions of exotic Bactrocera species in Torres Strait

Publication Date
Fri, 11 Apr 2014, 00:00
Last Updated
July 6, 2023, 5:54 a.m.
Report Number
Pest Id
Bactrocera sp. - (BCTRSP)
Report Status
Potential fruit fly hosts on inhabited Torres Strait islands include: banana (Musa spp.), man (Mangifera indica), papaya (Carica papaya), citrus (Citrus spp.), pumpkin (Cucurbita moschata), watermelon (Citrullus lanatus), guava (Psidium guajava), custard apple (Annona reticulata), soursop (Annona muricata) and Indian almond (Terminalia catappa). On some islands, small numbers of tomato (Solanum lycopersicum), capsicum (Capsicum annuum), beans (Phaseolus vulgaris), passionfruit (Passiflora edulis) and other tropical fruits also grown
Pest Status (old values from ISPM 8 -1998 )
  • Transient: actionable, under eradication
Pest Status (ISPM 8 - 2021)
  • Present: transient
Geographical Distribution
Transient detections on several islands in Torres Strait during the monsoon season (between December-June) in small scale community gardens on the inhabited Torres Strait islands. The Torres Strait is located more than 600 km from the nearest commercial production area at Lakeland Downs, north of Cairns (see attached maps). The islands of the Torres Strait, while part of Australia, hold a special quarantine designation. Under the Quarantine Act 1908, no plant or animal material or soil can be moved from the islands to the Australian mainland without meeting quarantine regulations. This is in recognition of the additional risk posed by proximity to Papua New Guinea and the relative freedom of movement of indigenous people between Papua New Guinea and the Torres Strait Protected Zone.

There is a permanent, native population of the exotic pest fruit fly species including Oriental fruit fly (Bactrocera dorsalis), New Guinea fruit fly (Bactrocera trivialis) and melon fly (Bactrocera cucurbitae) in the Western Province of Papua New Guinea immediately adjacent to the Torres Strait islands. Patterns of detection of these fruit flies provide evidence of wind-mediated natural dispersal events into Torres Strait. A permanent network of fruit fly monitoring traps is maintained on every inhabited island and several key uninhabited islands in the Torres Strait (Torres Strait Protected Zone and on the two main islands in the Special Quarantine Zone (see attached map)) Response and eradication measures start immediately following any detection of Bactrocera dorsalis, B. curcubitae, B. trivialis or other exotic fruit fly species. These measures include a combination of bait-spraying of plant foliage throughout the affected communities and enhanced monitoring, including the installation of additional traps on the affected island. Where the number of flies detected exceeds set thresholds, male-annihilation blocking is initiated and response traps are installed on alternative nearby islands. Fruit rearing is also undertaken to monitor for other exotic fruit fly species, including non-lure responsive species. Male annihilation blocks are removed from the island/s 12 weeks after the last detection and response traps are immediately reinstalled for a further 12 weeks on those islands to provide confidence that the incursion has been eradicated.

These pest species are only transient in the Torres Strait islands as evidenced by the continued absence of detection from islands following eradication measures for extended periods that may be over 12 months. The closest commercial production area is more than 600 km away from the southern part of the Torres Strait, in Lakeland Downs (between Cooktown and Cairns).
Contact for info
Australian Chief Plant Protection Officer Australian Government Department of Agriculture GPO Box 858 Canberra ACT 2601 [email protected]
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