Recipe for African farmlands

Damage by cassava green mite
Damage by cassava green mite. Photo by IITA

A natural enemy, capable of tackling the green mite menace, has been helping millions of Africans whose livelihoods depend on cassava.

The natural enemy, Typhlodromalus aripo, has proven to be an ideal candidate in controlling the cassava green mite (Mononychellus tanajoa) after 7 years of studies, says Dr Alexis Onzo, IITA entomologist based in Cotonou.

Back in the 1970s when the pest entered Africa, cassava green mite wreaked havoc on African cassava farms, depleting yields, in some cases, up to 80%.

Onzo says the neotropical spider mite attacks cassava—a major crop in Africa—by damaging the photosynthetically active leaf surface area of the plant.

The good news, however, is that the biocontrol option which saw the introduction of T. aripo in Africa has substantially reduced the population of green mites, as evident in studies carried out by scientists in southwestern Bénin and in many other countries in the African cassava belt. The results indicate that the introduction of T. aripo has helped in ensuring farms with healthier cassava plantations in Africa.

The predatory mite, T. aripo, was introduced by IITA and partners from Brazil, South America for the control of the cassava green mite. It resides primarily in the apices of the cassava plant, feeding on and reducing the populations of green mites not only in the apices but also in the upper part of cassava foliage.

Alexis Onzo inspects cassava leaves for pests
Alexis Onzo inspects cassava leaves for pests. Photo by IITA

Onzo says T. aripo was released in Africa by IITA and partners in the 1990s to contain the devastation caused by green mites. Since then the natural enemy has, on its own, been spreading to different parts of the continent, playing its role as a natural control agent against that cassava pest.

Unlike chemical control which wipes out the pests and other benevolent species, the biocontrol option reduces the population of the pest to a level that makes the pest’s impact on the crop economically insignificant. Besides, the pollution associated with chemical control is also avoided.

Onzo described the continuing success of green mite control in Africa as a welcome development and a victory for resource-poor farmers who will have the opportunity of cultivating healthier cassava farms.

With the prevention of the devastation by green mites and other pests, cassava has now become a cash crop in Africa, generating wealth and improving the food security of many Africans.

“Today we see cassava serving as a raw material in the flour, ethanol, and glucose industries. Even the governments are benefiting from these benefits,” he says.

As cassava green mite becomes less of a problem, Onzo says he intends to take up the fight against mites that are ravaging and depleting the production of coconuts and vegetables in Africa.