By Sharon Atieno

Insect pests such as fruit flies have resulted in huge losses for farmers across Africa as they reduce the quality and quantity of the marketable fruit. The situation is so bad that it is estimated that around two billion US dollars are lost yearly in Africa due to fruit fly infestations.

“When the fruit flies attack the fruits, they lay eggs in them. These eggs develop in to maggots and eat the fruit flesh. As a result, the infested fruits quickly become rotten and inedible, eventually falling off the tree,” explains the International Centre of Insect Physiology and Ecology (ICIPE).

The odour bait trap on a mango tree

In a bid to solve the problem of fruit flies, ICIPE in collaboration with other partners developed integrated pest management (IPM) packages for exotic and native fruit flies.

Some of these techniques include: baiting and male annihilation techniques; biological control with biopesticides and parasitoids; cultural control through field sanitation and minimal use of pesticide in localised bait stations of spot spray.

“Before the biocontrol techniques were developed, we used to use a lot of pesticide to spray the fruits. The effort in most cases was futile because by the time you spray most of the fruit flies are in hiding,” says Kioko  Mutinda, a Kenyan farmer in Machakos County, “by the time they come back, the pesticide has waned off and it is no longer effective.”

Mutinda has a portion in his farm where he grows mangoes. It is at this portion where he has set up two biological control traps for the fruit flies.

“This technique kills a lot of the male fruit flies. The trap has a scented block which attracts the males who think they are coming to mate but instead, the bait which contains poison ends up killing them,” he adds.

Dead Fruit flies inside the trap

Mutinda says that the odour bait covers up to 500m, hence being a small scale farmer, he does not have to use so many for his mango farm though he plans on adding one or two more.

The project was at its preliminary stages when socio-economic assessment studies were conducted in 2014 to determine the impact of the ICIPE IPM packages on mango production in Embu and Meru counties.

In Embu, the study found that there is an average reduction of 54.5 percent in the amount of mango produced being rejected by buyers, 46.4 percent decrease on insecticide expenditure and 22.4 percent increase in net income that farmers were getting from mango production.

Similarly, the study in Meru revealed that mango losses due to fruit fly infestations decreased by 17 percent while expenditure on pesticides reduced by 45 percent. Moreover, the net income of farmers using the ICIPE IPM packages in mango production had risen by about 48 percent, which was very high compared to that of other growers.

The biological control strategies have greatly improved yields not only in Kenya, but across different African countries with more plans of scaling up. Through such methods, smallholder farmers are assured of food security and are able to improve their living standards.