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Sugar sweet ants March 15th, 2015 by

It hardly seems fair that organic orange juice is sour, but there is a way to sweeten it, with ants!

In 2009, Professor Kwame Afreh-Nuama from Legon University in Ghana took me to the Coastal Outgrowers Association, an organic citrus-producing association in the Abura-Asebu-Kwamankese district in the Central Region. The outgrowers were enjoying top-notch international support. As early as 2006, a German-funded project (Market-Oriented Agriculture Programme) asked WAFF (West Africa Fair Fruit Company ) to help the outgrowers’ association prepare 1000 farmers for certification, which it did. Several thousand other farmers later joined to become organic producers.

WAFF is a social enterprise that organizes farmer groups into a supportive network of NGOs, grassroots organizations and fruit companies, and helps them to certify organic fruit.  The private Ghanaian fruit-buying company Coastal Grove Ltd. buys fruit from the Coastal Outgrowers Association to produce organic orange juice for local and export markets.

Organizing and training thousands of farmers to comply with organic standards was a huge challenge, and just as it was reaching what should have been a successful conclusion, victory was snatched away by a new species of fruit fly, recently arrived in West Africa. The invasive fruit fly causes devastating losses in many orchards.

To control the flies without chemicals, the organic farmers started to harvest their fruit earlier, but the unripe oranges had less sugar and their juice was not as sweet.

So I suggested a readily available solution; weaver ants could improve the sugar content in the juice by allowing farmers to harvest later.

Talking with various people in Ghana, I heard the same old story I had heard in Southeast Asia, and elsewhere in West Africa. Farmers and others in the value chain perceived weaver ants as a pest and systematically killed them. In part this is because the territorial ants will bite harvesters and other people who are working in the trees.

But weaver ants are a keystone natural enemy. They are fierce predators that kill many kinds of insect pests. The ants live in large colonies and are totally adapted to life in the trees, sewing leaves together to make nest chambers, and connecting parts of the colony with paths along the tree branches. Apart from being predators, weaver ants also protect fruit trees in other ways. While ants patrol the trees, they deposit marks on the branches, leaves and fruits which fruit flies are able to detect. Not wanting to risk their lives, fruit flies wisely look for other places to lay their eggs.

On the way back from Tamale we crossed the north of Togo and entered Benin to visit various radio stations. I was happy to learn that Radio Communautaire Ilèma at Dassa had made active use of the book Ants as Friends. The radio broadcaster had learned the importance of conserving weaver ants and said that one of the older mango plantation holders in a nearby village had successfully established weaver ant colonies and ‘ant bridges’ between his various trees.

Good communication tools require motivated people and channels to reach farmers. In the future, a series of training videos on how to deal with fruit flies would benefit farmers, fruit processors and consumers. After all, consumers love organic orange juice, but not if it is sour!

The training manual “Ants as Friends: Improving your Tree Crops with Weaver Ants” is downloadable for free in five languages:

English (2003, 2007)
French (2008)
Khmer (2010)
Vietnamese (2005)
Bahasa Indonesia (2004)

Other publications on weaver ants are downloadable from the Agro-Insight Resources Section.

Scientific names:

Weaver ant: Oecophylla smaragdina (Asian species), Oecophylla longinoda (African species).

Invasive fruit fly: Bactrocera invadens

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