|Wednesday, 16 January 2013 09:02|
Samoa (previously known as Western Samoa) is a Polynesian country formed of two large volcanic islands (Upolu and Savai'i) totaling 2935km². The highest point is Mount Silisili (1858m) on Savai'i.
In an early effort to control fruit flies, three parasitoid species were introduced into Samoa between 1935 and 1938, and one of them, imported from Fiji, became established.
In December 1990, full time fruit fly research started in Samoa, when the Regional Fruit Fly Project posted a United Nations Volunteer, who trained the National counterpart staff until late 1995. Fruit fly activities are coordinated by the Samoa Ministry of Agriculture, Forests, Fisheries and Meteorology. New Zealand has contributed funding and expertise for the development of heat treatment through the Horticulture and Food Research Institute of New Zealand. A parallel project was also conducted by the Australian Centre for International Agriculture Research (ACIAR) to support research on fruit fly surveys and protein bait spraying.
Fruit fly quarantine surveillance and research is critical in Samoa, where banana has replaced taro as main staple crop after the establishment of taro leaf blight in 1993. Samoa must be kept free of highly destructive fruit fly pests of bananas (B. musae, B. papayae and B. dorsalis).
The fruit fly research facility is located at Nu'u Research Station, on Upolu Island. For more information, contact:
Laisene Samuelu, Assistant Chief Executive Officer, Crops Research Division, Ministry of Agriculture and
FRUIT FLY SPECIES: There are seven species. The two main economic species are Pacific fruit fly (B. xanthodes) and B. kirki. Bactrocera distincta is a minor pest of star apple (Chrysophyllum cainito). The non-economic species are B. obscura, attracted to Cue-lure, and three others not attracted to male lures: B. aenigmatica (Malloch), B. samoae Drew, and B. new species near paraxanthodes.
ECONOMIC IMPORTANCE OF FRUIT FLIES: Pacific fruit fly (B. xanthodes) infests 19-37% of a local variety of papayas and 4-41% of Sunset variety papayas. Bactrocera kirki infests 45-99% of ripe guavas.
Surveys: 1. Established and maintained a fruit fly rearing laboratory and laboratories for holding fruit samples collected in the field and undertaking heat tolerance studies at Nu'u Crop Development Centre. 2. Established permanent trapping sites on the two islands in Samoa. Trap sites made up of one trap baited with methyl eugenol and one with Cue-lure. 3. Collected and held in the laboratory for adult fly emergence commercial/edible and wild/forest fruit samples. 4. Determined that there are seven species of fruit flies (Tephritidae: Dacinae) in Samoa and compiled host ranges for all species. Used this data as the basis for negotiations on quarantine protocols for export of fruits and vegetables.
Pest status: 5. Confirmed that only two species are on economic importance – B. kirki and B. xanthodes. 6. Determined, by host surveys, the level of damage caused by fruit flies to guava (45-99%) and papaya, (4-37%). Fleshy vegetables are virtually free from fruit fly infestation.
Quarantine surveillance: 7. Modified the initial fauna surveys into an early warning system as part of the Samoa's overall quarantine surveillance system. Trapping focused on high-risk locations, such as tourist resorts, urban areas, educational institutions for overseas students, markets, farming areas, diplomatic missions and ports of entry. 8. Fruit fly surveillance during the September 2007 South Pacific Games (SPG) involved placement of fruit fly traps in the Games Village with weekly monitoring and clearances carried out by the Samoa Quarantine Officers. To-date, there has not been any new fruit fly species found in the traps.
Laboratory colonies: 9. Established laboratory colonies of B. kirki, B. xanthodes and B. samoae reared on papaya-based diet and developed and adapted laboratory rearing techniques for three species of fruit flies, using various artificial diets and egging devices. 10. Completed studies on the life cycles and rates of development of B. kirki, B. xanthodes and B. samoae in artificial diet and in fruits such as papaya.
Field control: 11. Conducted preliminary tests of protein bait spraying in papaya orchards.
Host status testing and export markets: 12. Used the laboratory and field tests to determine non-host status test for fruits and vegetables developed by the RMFFP and the New Zealand Ministry of Agriculture and Forestry (MAF) Regulatory Authority. 13. Exported 152 tonnes of green bananas to New Zealand in 1998 under non-host status quarantine treatment. Proved that Tahitian and West Indian limes are not susceptible to fruit flies in Samoa.
Heat treatments and export markets: 14. Generated with the help of Hort + Research New Zealand, data on the heat tolerances of early and late eggs, first instar and feeding and non-feeding third instars of B. kirki and B. xanthodes and had these data accepted by New Zealand. 15. Samoa through its Stabex funds has purchased and installed a research/semi commercial HTFA unit. This unit is based at the Atele Horticultural Centre, currently run by the Ministry of Agriculture's Crops Division. The unit is able to carry out research on commodities destined for export and also treat fruit for export. The current commodities targeted for export are breadfruit and papaya. 16. First shipment of papaya exports to New Zealand took place on the 10th June 2004. 30 cartons of papaya were sent to New Zealand on this shipment. Since then the second shipment of papaya took place on the 17th June.17.First shipment of breadfruit exports to New Zealand took place on the 2nd of November 2004 and as required under the protocol, all registered breadfruit farms have been sprayed every fortnight with protein bait (Tongalure & Batrogel/Fipronil). 18. Export of eggplants (Black beauty variety) to New Zealand started in August 2006 and by November, a total of four shipments have already been exported.
HTFA unit in Samoa, with designer Dr. Michael Williamson (left) (Photo: Ema Tora Vueti)
Development of National expertise: 19. Published in the ACIAR Proceedings No. 76 of the Symposium on the Management of Fruit Flies in the Pacific, one scientific paper on fruit flies in Samoa. 20. Provided training to farmers and government personnel of Samoa on the importance of fruit flies to production and national quarantine, identification, control methods, and quarantine treatments.21. Three technical staff from the Ministry of Agriculture visited Fiji in April 2006 to study procedures involved in the Fiji BQA export system to New Zealand (Systems Approach). 22. Samoa's leading fruit fly scientist was funded by SPC Biosecurity to attend and make presentations on Samoa's fruit fly programs at the Sixth Annual Meeting & Review of the Hawaii Fruit Fly Area Wide Pest Management (AWPM) program. Apart from attending the meeting and making presentations, she also visited and studied the Area Wide field programs in Hilo, as well as the sterilization, parasites and fruit fly mass rearing facilities in Honolulu.
Emergency response planning: 23. Increased preparedness to detect quickly an incursion of an exotic fruit fly species and formulated an Emergency Response Plan to eradicate any introduction of a new unwanted species.
STATUS OF QUARANTINE SURVEILLANCE (as of October 2007): There are 25 trapping sites on Upolu and 10 in Savaii each with one Cue-lure and one methyl eugenol trap. Samples of the following commodities are regularly collected for quarantine surveillance: guava, breadfruit, mango, pacific almond, Tahitian chestnut, orange, capsicum, chillies, tomato, papaya, avocado, banana, soursop, mandarin, lemon, kumquat, eggplant, cucumber, bittergourd, melon, Syzygium apples, pumpkin and wild fruits. There are fruit fly posters at the wharfs and airports and quarantine bins at the airports.