MALE ANNIHILATION TECHNIQUE TO CONTROL FRUIT FLIES IN 
PACIFIC ISLAND COUNTRIES AND TERRITORIES

Male Annihilation Technique (MAT) involves the use of a high density of bait stations consisting of a male lure combined with an insecticide (usually technical malathion, and more recently fipronil), to reduce the male population of fruit flies to such a low level that mating does not occur.  This is achieved by distributing cordelitos (lengths of 6-ply cotton string about 30-45 cm) or caneite (compressed fibreboard) blocks (50 mm x 50 mm x 12.7 mm), or coconut husk blocks (50 mm x 50 mm x 10 mm) impregnated with the lure/insecticide mixture.  These are distributed from the ground or air in densities of at least 400 per km².  This treatment is repeated every eight weeks.  There are several examples of the successful use of methyl eugenol in the technique.  Oriental fruit fly (Bactrocera dorsalis) was eradicated from Guam and the Commonwealth of the Northern Mariana Islands in the 1960s by Steiner and his colleagues.  The insecticide used during the eradication was naled.  Outstanding successes using this method have been recorded for eradicating oriental fruit fly from California and from the Amami Islands of Japan.

Caneite blocks and coconut husk blocks for male annihilation (Photos: Allan Allwood).

More recently, this method, using lengths of string or cord soaked in methyl eugenol and malathion, was successful in eradicating Asian papaya fruit fly (Bactrocera papayae) from several Torres Strait Islands, in an effort to keep this species out of Cape York in Queensland.  A similar method, using caneite blocks nailed to trees instead of using string, was used to successfully eradicate Asian papaya fruit fly from the Cairns area of northern Queensland during the late 1990's.

In the Pacific Island Countries and Territories (PICTs), eradication programmes have been carried out against oriental fruit fly in Tahiti and Moorea, and four species [oriental fruit fly, Pacific fruit fly (B. xanthodes), melon fly (B. cucurbitae), and mango fly (B. frauenfeldi)] on Nauru.  Impregnated coconut husk blocks treated with methyl eugenol and malathion were distributed by ground teams and from the air by helicopter in Tahiti and Moorea six times in 1997, in an attempt to eradicate oriental fruit fly.  Hot spots of breeding fly populations were not completely eradicated, and from these, fly populations spread again over the two islands.  MAT to eradicate the species was resumed in 1999.  In Nauru, oriental fruit fly and Pacific fruit fly were eradicated in early 1999 and early 2000, respectively, with caneite blocks (50mm x 50mm x 12.7mm) treated with methyl eugenol and using fipronil instead of malathion.

The effectiveness of using Cue-lure for male annihilation of species attracted to it is not as great as that using methyl eugenol.  Therefore, past attempts at using Cue-lure to eradicate melon fly populations have been unsuccessful.  During 1998-1999, though, melon fly was eradicated from Nauru, using caneite blocks treated with Cue-lure and fipronil.  The prolonged drought and the resultant reduction in cucurbit host availability were favourable conditions that facilitated its eradication.  Mango fly (Bactrocera frauenfeldi) is the only species remaining in Nauru, and the application of Cue-lure-treated blocks, in combination with protein bait spraying, has reduced populations to very low numbers.

 

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