Natural pest control boosts fruit farmer fortunes in southern Africa

Mango farmers in southern Africa are adopting natural pest control methods to thwart the oriental fruit fly, Bactrocera dorsalis. 

This destructive pest, first detected in Africa in 2003, can ruin a farmer’s entire harvest. Costly pesticides have been largely ineffective at reducing infestations, leading farmers to throw away thousands of tonnes of mangoes and other fruit each year. However, integrated pest management techniques are improving the odds for fruit farmers and increasing their yields and incomes. 

Fighting the fly 

With financial support from the Cultivate Africa's Future Fund (CultiAF), a partnership between IDRC and the Australian Centre for International Agricultural Research (ACIAR), scientists at the  International Centre of Insect Physiology and Ecology in Nairobi developed the fruit fly integrated pest management package. Under the CultiAF project, researchers have produced and promoted their innovations. These include baiting and trapping the flies and releasing the fruit fly’s natural enemies to control populations.  

Since 2019, the project “Alien invasive fruit flies in southern Africa” has been working across Malawi, Mozambique, Zambia and Zimbabwe to scale up the adoption of integrated pest management. It has targeted 4,000 farmers in the region with the goal of improving food security and nutrition by protecting mango yields, providing income-generating opportunities by providing training in fruit drying and preservation and, ultimately, reducing poverty among small- and medium-scale mango growers in southern Africa, particularly women and youth. 

So far, more than 9,000 men and women farmers have been trained in integrated pest management  technologies — more than double the project target. The farmers have since implemented some of the tools, particularly the male-annihilation technique, which involves mass trapping the male fruit flies using attractants such as Methyl eugenol, Curelure and Trimedlure, combined with insecticide. The tool reduces male populations and therefore significantly reduces mating among the flies.  

The project has also provided farmers with ”bait stations” — small plastic containers that hold food bait for fruit flies. Inside the bait is an insecticide that kills the flies. The stations can be hung on mango trees or placed around the orchard.  

Another integrated pest management technology that has helped farmers fight the fruit flies is a tent-like structure called an augmentorium, which is fashioned out of plastic or netting and used by farmers to store fallen, infested fruits. The augmentorium traps fruit flies because they are too large to pass through the netting holes, but it allows parasitoids (small insects and natural enemies of the fruit fly) to escape. The parasitoids lay their eggs on the bodies of fruit flies and as the eggs mature and emerge as adult insects, the process kills the fruit flies. 

Insect-free incomes 

Sailor Chimbwali, a farmer from Chilanga District, 40 km from Zambia’s capital city, Lusaka, received training in integrated pest management approaches in 2020. Previously he had poor yields and low sales because he had to throw away a lot of mangoes without knowing the cause of the rot, but the tools have helped him control fruit fly populations at his farm.   

“I learned that fruit flies destroy mangoes, resulting in a loss of income for me. I now use lures to attract male flies to a poison, eliminating fly reproduction. integrated pest management is effective and helpful,” said Chimbwali, who has increased his mango income by Zambian kwacha (ZK) 3,900 (approximately CAD$280).  

Morris Chiwala, a farmer from Lusaka Province, said that using integrated pest management techniques has improved his livelihood because he has been able to earn enough money to send his children to school and to build a better house. Before he started using the integrated pest management approaches in 2019, most of the mangoes from his trees were dropping before ripening.  

“My yield has increased from 60 to 115 baskets [at 15 kg each] per season,” Chiwala enthused, explaining that his income from selling fresh mangoes has nearly doubled since adopting the integrated pest management package (from ZK 6,000 to 11,500 (approximately CAD$430 to CAD$824). In addition, he and his family are enjoying a more balanced diet now that he can afford to buy more varied foods. His higher income has also allowed him to venture into other agricultural projects such as poultry rearing and selling produce from a small vegetable garden.  

According to Linda Muzungaire, one of eight agricultural extension officers trained by the project, many farmers were unaware of fruit flies prior to the CultiAF project but can now identify their presence in rotting fruit.  

“Last year, we trained farmers on integrated pest management and the lead farmers — influential and successful farmers in the community — have been able to demonstrate the benefits of the approaches to other farmers and convince them to use integrated pest management,” Muzungaire remarked. She works with more than 300 farmers and said they have reported less rotten fruit and therefore more orders from customers. 

“Initially, we had the challenge of convincing farmers about the benefits of integrated pest management for mangoes because many believed that they could only generate income from other crops,” Muzungaire noted. She further explained that before integrated pest management methods were introduced, farmers were eating or giving away unrotten mangoes because  they didn’t realize their value. Since the training, farmers appreciate mango growing as a business and the importance of maintaining healthy trees and fruit. 

A new market for dried mango 

Chiwala also started producing dried mangoes using a drying-basket innovation provided by the project. The baskets, which 28 farmers have been trained to make, are fashioned out of woven polyester cloth wrapped around wire frames. Each has between three and seven compartments to dry the fruit, which takes half a day to dry on warm days.  

“I place ripe mangoes cut into small pieces inside the baskets for drying. This has improved my income since dried mangoes fetch more money than fresh ones,” said Chiwala. He explained that a basket of fresh mangoes fetches ZK 100 (approximately CAD$7.10) while a basket of dried mangoes costs ZK 800 (approximately CAD$57). Last season he earned ZK 4,000 (approximately CAD$287) from five baskets of dried mangoes. 

Thus far, 27 women and one man in Zambia have learned how to make the mango driers and a total of 450 women have benefitted from using the driers, Muzungaire said. On average, each farmer dried about 4 kg of mangoes during the 2021 fruiting season. The women are also drying vegetables such as sweet potatoes, pumpkin leaves, cowpeas and tomatoes for later use, which increases household food security. These preserved foods can also be sold to earn an income.  

The project has also provided mango-drying training to more than 800 farmers in the Mutoko, Murehwa and Zvimba districts of Zimbabwe. Despite it being their first time to dry the fruit, and during the rainy season no less, the farmers produced 216 kg of dried mango in 2022 from approximately 270 baskets.  

For farmer Emily Chakanyuka from Murehwa District, the training has paid dividends: “I dried a good quantity of mangoes in February and was able to realize up to 2,545 Zimbabwean dollars [approximately CAD$192] from what I sold,” she said. “I am happy to have learned how to dry mango because it is a tasty food!” 

Nyepudzai Kamundi from Mutoko District agreed: “My family loves mangoes and I feel sad that I have denied them this delicacy because I prepared very little of it previously. I have also taught other farmers how to dry mangoes and those who have tasted them really enjoyed them.”  

Kamundi, who has 40 mango trees, explained that she harvests her mangoes, then washes and cuts them into wedges. After that, she dips them into water with lemon, which speeds up the drying process while keeping flies at bay, and places them in the basket dryer. 

“Drying can take a week or two depending on the weather,” Kamundi said, noting that the farmers had dried the mango during the rainy season. She dried 5 kg of mango and sold seven 1 kg packets at the local shops at 180 Zimbabwean dollars (approximately CAD$0.65) and showcased some of it at a local food fair. “People love the dried mango and I am convinced I will be able to make more this coming season and gain more income. I am thankful for the training I got,” she said.