Mango farmers in Senegal are learning how used plastic water bottles and a few dollars could save hundreds of dollars they lose annually to a fruit-destroying fly.

Government agriculture officials and aid groups are training producers in the use of a trap made of local and recycled materials – far cheaper and more accessible than imported traps. In turn the producers will train other farmers.

The effort is expected to provide considerable relief to mango producers who for at least four years have seen the fly gut their livelihoods. Mangoes have become particularly important to many farmers in the embattled Casamance region since landmines have forced them to give up other crops.

“This is really a huge sigh of relief for the farmers of Casamance,” said Ibou Goudiaby, who has five hectares of mango trees just south of the Casamance capital, Ziguinchor.

“This will allow us to recover our plantations, which are our only source of revenue until demining is complete.” He called for stepped up efforts to train farmers in methods to kill off the fly, saying, “Without this effort all of Casamance would sink into misery because most of us are cultivators.”

Residents across Casamance are being hit by food shortages due to poor rains. And many families depend on mango crops because they grow during the rainy period – from July through September – the lean period for other crops. Farmers in Senegal live on the export of mangoes as well as their local sale.

Farmers told IRIN the method should be applied across the region as soon as possible, since mango trees start to flower in January.

Commercial traps are available, but they cost 7,800 to 12,000 CFA francs (US$17 to $27), according to Mamadou Dabo, crop protection engineer with the Agriculture Ministry, so agriculture experts and NGOs are showing producers how to make their own. Using recycled plastic water bottles and a few other local supplies the cost shrinks to about 2,500 CFA francs.

The method uses a substance that attracts the flies and then traps them in a specially designed receptacle. In trials in July and August, the trap captured an estimated 60,000 flies in 10 days.

“The key is to put the technique out there and get local farmers using it and teaching it – to help them take on this fight,” Dabo told IRIN.

The Agriculture Ministry and development NGOs had to study the biology of the fly to determine the best technique, Dabo explained. The female fly pierces a mango and lays eggs in the ripening fruit. In two to four days the eggs hatch, releasing maggots that cause the fruit to rot and fall to the ground. Once the infested mango falls the larvae bury themselves in the soil to mature then emerge, restarting the destructive cycle.

Experts note that keeping plantations clean and free of debris is the first line of defence. It is recommended that farmers bury fallen fruits at least 50cm deep.

Experts continue to study the biology of the fly, so as to tackle the problem and stave off infestations of other crops, Dabo said, adding that there have been reports of the flies attacking tomatoes and other fruits.