Nauru Eradication
Thursday, 31 January 2013 13:51


The Republic of Nauru was home for four species of fruit flies – Oriental fruit fly (Bactrocera dorsalis), Pacific fruit fly (B. xanthodes), melon fly (B. cucurbitae), and mango fly (B. frauenfeldi). All four species were introduced, with melon fly and Oriental fruit fly being introduced in about 1985 and the other two species being present at or just after World War 2.


As Nauru did not have a quarantine service and had a national airline that flew to Fiji, FSM, Guam and Australia, there was a risk that these fruit fly species may be carried in fruit by passengers and be inadvertently introduced to other countries in the Pacific. For these reasons, the FAO/UNDP/AusAID/SPC Project on Regional Management of Fruit Flies in the Pacific (RMFFP) combined resources with the Crawford Fund for International Agricultural Research, the private sector in Australia (Bronson and Jacobs and Rhône Poulenc Rural (Australia)), and the Governments of Nauru, Australia and New Zealand, to eradicate all four species. The programme commenced in October 1998.


The techniques used to eradicate fruit flies consisted of a combination of male annihilation and protein bait spraying. The principle of male annihilation is to reduce the male population to such a low level that no mating occurs and, as a result, the fruit fly population crashes.


Male annihilation was achieved by distributing fibreboard blocks (50mm x 50mm x 12.7mm) soaked in male lures and an insecticide, called Fipronil, at intervals of 50 metres over all areas of Nauru accessible to ground teams. The male lures were methyl eugenol, which attracted male Oriental fruit flies and Pacific fruit flies, and Cue-lure, which attracted male melon flies and mango flies. Blocking was repeated every eight weeks, resulting in fourteen campaigns up to December 2000. Six ground teams supplied by the Nauru Government, National Phosphate Corporation and Buada Lagoon Council, were responsible for nailing the treated blocks to trees. Each campaign resulted in about 7,000-8,000 blocks being distributed.

Blocks are treated with a mixture of male lure to attract male flies and Fipronil to kill them (Photo: A. Allwood)

Block nailed to tree trunk (Photo: A. Allwood)

Protein bait spraying works on the principle that female flies require a feed of protein before they are able to lay viable eggs. A protein, called Mauri Pinnacle Protein Insect Lure, was combined with the insecticide Fipronil and was sprayed as large droplets onto leaf surfaces of fruit trees. Protein bait spraying was done by teams of youth, who applied about 180 litres of protein to most host fruit trees in Nauru once a week between October and December 1999. Since February 2000, protein bait spraying has been maintained by a team of maintenance workers from Nauru Phosphate Corporation (NPC).

Within twelve months, it was possible to declare that Oriental fruit fly and melon fly were eradicated from Nauru. The President of Nauru, His Excellency Mr. Rene Harris, made this official declaration at a public meeting in Nauru on Monday, 6 December 1999.


Pacific fruit fly has not been recorded since February 2000, so its eradication is also imminent. The population of mango fly has been reduced to a very low level – less than two flies per trap per week now compared to 1,500 per trap per week twelve months ago.


For the first time since 1985, people in Nauru are able to eat ripe mangoes. In October 1998, about 90% of mango fruits were infested with fruit fly maggots, mainly Oriental fruit fly. Now, fruit is virtually free from fruit fly infestation. Improved fruiting of breadfruit is also obvious as a result of eradication of Oriental fruit fly and the near eradication of Pacific fruit fly.

People of Nauru can enjoy ripe mangos again (Photo: A. Allwood)


The Nauru Government should be congratulated for its support of the programme and also for enacting a new Agricultural Quarantine Act, which now allows the Government to control the entry of fruits and vegetables from overseas. SPC and the RMFFP will provide training for Quarantine Officers in Nauru in 2000.

Through the eradication programme in Nauru, it has been possible to provide hands-on training and experience on eradication methods and the development of emergency response plans to cope with outbreaks of exotic fruit flies to 45 plant protection and quarantine officers from 19 Pacific Island countries and territories and from SPC.