|Wednesday, 16 January 2013 09:52|
Tonga (747 km²) has 170 islands, 36 of which are inhabited. The Kingdom is divided into four main island groups (from south to north): Tongatapu group to the South (includes the Capital Nuku'alofa), the Ha'apai group, the Vava'u group, and the isolated Niuas. The largest and most populated island is Tongatapu (259 km²).
Trapping and host fruit surveys for fruit flies in Tonga started in 1973-74, with the work of J.A. Litsinger. Other and subsequent surveys were done in 1973-76 (FAO/UNDP/SPEC), 1977-78 (by P.S. Crooker) and 1980-82 (by N. von Keyserlingk). Results from these early surveys are summarized in Litsinger et al (1991). Surveys were resumed in 1987 after fruit fly larvae were found in a watermelon exported to New Zealand, which resulted in a ban on watermelon imports.
The involvement of the Regional Fruit Fly Project (RFFP) in Tonga started in September 1990, with the appointment of a United Nations Volunteer, who trained the National counterpart staff until late 1995. Fruit fly activities in Tonga are coordinated by the Tonga Ministry of Agriculture, Forestry and Fisheries (MAFF). 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. A special ACIAR Project (No 7500) helped with the development of technology to convert brewery waste yeast into protein lure to control fruit flies, in cooperation with the RFFP and the USDA - Commercial Agricultural Development Project. The RFFP and USDA Agriculture Research Services, based in Hawaii were instrumental in developing forced hot air treatment technology in Tonga.
Fruit fly quarantine surveillance and research is critical in Tonga, which has a multi-million dollars squash export industry to Japan. Tonga must be kept free of destructive fruit fly pests of Cucurbitaceae (melon fly, pumpkin fly, B. atrisetosa, B. strigifinis, D. solomonensis, B. papayae, B. dorsalis).
The fruit fly research facility in Tonga is located at Vaini Research Station, 15 km away from Nuku'alofa. For more information, contact:
Dr. Viliame Kami, Quarantine and Quality Management Division,
Protein bait for fruit fly control is manufactured locally
FRUIT FLY SPECIES: There are six species. Bactrocera facialis is widespread in all Tonga except the Niuas. Pacific fruit fly (B. xanthodes), B. kirki and B. distincta are widespread on all four island groups. Bactrocera passiflorae is restricted to the Niuas. It may in fact be the sibling species with pale abdomen. Its correct identity requires confirmation. The non-economic B. obscura is common in the Niuas and very rare in the more southern groups of islands.
ECONOMIC IMPORTANCE OF FRUIT FLIES: Bactrocera facialis is an extremely damaging pest fruit fly. It destroys 97-100% of capsicum and 89-97% of chilli. B. facialis and B. kirki are collectively responsible for 90% infestation on guava.
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 Vaini Research Station. 2. Established permanent trapping sites on six islands of Tonga. Trap sites made up of one trap baited with methyl eugenol, one with Cue-lure and one Trimedlure trap (against Mediterranean fruit fly). 3. Collected and held in the laboratory for adult fly emergence commercial/edible and wild/forest fruit samples. 4. Determined that there are six species of fruit flies in Tonga (Tephritidae: Dacinae) 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 three species are of economic importance on Tongatapu – B. facialis, B. kirki and B. xanthodes. 6. Determined, by host surveys, the level of damage caused by fruit flies to guava (90%), chilli (89-97%) and capsicum (97-100%). 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 Tonga'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.
Laboratory colonies: 8. Established laboratory colonies of B. facialis, B. xanthodes and B. kirki reared on papaya-based diet. 9. Completed studies on the life cycles and rates of development of B. facialis and B. xanthodes.
Field control: 10. Developed a package for field control of fruit flies, based on sound crop hygiene and protein bait sprays. Adopted by farmers and exporters as a component of export pathways for papaya (NZD 47000 worth exports in 1998), watermelon (NZD 42000 in 1998) and "Bird Eye" or "Super" chilli to New Zealand. 11. Conducted research to modify waste yeast from the Royal Brewery of Tonga as an inexpensive source of protein for protein bait spray (with excess being available as protein additive for stock-feed). (more information) 12. Carried out extensive field trials to compare effectiveness of locally produced protein bait with Mauri's Pinnacle Protein Insect Lure imported from Australia, at controlling fruit flies on capsicum and chilli in Tonga. 13. Marketed Royal Tongalure since March 1998, produced from waste yeast by Royal Brewery. Saving in using local source of protein is substantial – TOP 2.00 per litre compared to TOP 30.00 for Mauri Pinnacle Protein Insect Lure imported from Australia.
Technology transfer: 14. Assisted with the transfer of technology on brewery waste yeast modification to Vanuatu Tusker Brewery.
Host status testing and export markets: 15. Used the laboratory and field tests to determine non-host status for fruits and vegetables developed by the RMFFP and the New Zealand Ministry of Agriculture and Forestry (MAF) Regulatory Authority. 16. Exported 'Candy Red' and 'Sugar Baby' watermelon varieties under non-host status quarantine treatment. Proved that cucumber, zucchini, "Bird eye" chilli are not susceptible to fruit flies in Tonga.
Heat treatments and export markets: 17. Generated and published data on the heat tolerances of early and late eggs, first instar and feeding and non-feeding third instars of B. facialis and B. xanthodes and had these data accepted by New Zealand. 18. Undertook commercial-scale confirmatory tests for export of papaya using forced hot air and submitted research reports to New Zealand MAF for approval of the treatment. Quarantine treatment uses forced hot air to raise the core temperature of the largest fruit placed in the coolest spot in the chamber, determined by thermal mapping, to 47.2°C and hold it at that temperature for 20 minutes before hydro-cooling. 19. In 1998, 7.5 tonnes of papaya (value of NZD 47,000) were exported to New Zealand, using the forced hot air treatment.20. The Tonga HTFA facility has been acredited by NZMAF in October 2004 for export of Breadfruit, Chilli, Eggplant, Mango, Papaya, Tomato and Avacoado under a Bilateral Quarantine Agreement (BQA) with NZ.
Development of National expertise: 21. Published in the ACIAR Proceedings No. 76 of the Symposium on the Management of Fruit Flies in the Pacific, five scientific papers on fruit flies in Tonga. 22. One Quarantine staff undertaking Masters Degrees at tertiary institution based in Apia. 23. Provided periodic training to farmers and exporters and government personnel of Tonga on the importance of fruit flies to production and national quarantine, identification, control methods, and quarantine treatments.
Emergency response planning: 24. 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 20 trapping sites on six islands: Tongatapu (7 sites), Vava'u Group (3), Ha'apai Group (3), Eua (2), Niuatoputapu (2), Niua Fo'ou (2). Each site has a Cue-lure trap, and methyl eugenol trap. There are 2 Trimedlure traps placed at the wharf and airport in Tongatapu. Regularly sampled fruits for research and quarantine surveillance are avocado, banana, chillies, sweet orange, custard apple, sour orange, devils apple, tangellos, mandarin, breadfruit, capsicum, chilli, eggplant, guava, mango, Pacific almond, papaya, soursop, Syzygium apples, Tahitian chestnut and tomato. All trapping and host fruit survey data are compiled on Excel spreadsheets. There are fruit fly posters at the airport and the wharf, as well as quarantine bins at the airport. There is a quarantine awareness program running on the radio every morning.
Download Pest Advisory Leaflet on Fruit Flies in Tonga in English (391 Kb)