A nature-based solution is showing remarkable success in helping farmers in Kenya, Uganda, and South Sudan sustainably restore their papaya (pawpaw) production devastated by the papaya mealybug pest.
The papaya mealybug, Paracoccus marginatus, is a highly destructive pest that has spread rapidly across East Africa, slashing yields, shortening orchard lifespans, and threatening food security and livelihoods.
Dr. Selpha Miller, an Invasive Species Management expert, disclosed this in an interview with reporters during a visit to the Crop Protection Biological Control Laboratory in Kenya on Tuesday.
She explained that the intervention involves a classical biological control strategy using a parasitic wasp, Acerophagus papayae, which effectively targets and suppresses the papaya mealybug population. Miller noted that Nigeria is also not exempt from the pest’s threat.
The visit formed part of a pre-tour ahead of the World Congress of Agricultural Journalists (WCAJ) scheduled to take place from October 15 to 18 in Nairobi, Kenya.
According to her, papaya is a vital fruit in East Africa, serving both as a food source and a major cash crop for smallholder farmers.
She said the pest, originally from Central America, was first detected in Africa in 2010, reached Kenya in 2016, and later spread to Uganda in 2021.
“The pest can cause up to 91 per cent crop loss, estimated at about £2,223 per hectare annually,” Miller said.
She explained that Kenya, in partnership with the Centre for Agriculture and Bioscience International (CABI)—a global non-profit organization—initiated the biological control programme using the parasitic wasp to combat the pest in both coastal and inland regions.
“When all other control methods failed, the parasitoid became the most effective tool against the invasive pest,” she said.
Miller revealed that mass releases of the wasp began in December 2021, with over 1.8 million parasitoids distributed to 990 farmers across nine countries.
“So far, 3,679 farmers in all nine countries have been trained and sensitized on papaya mealybug control using Acerophagus papayae. The project has also built the capacity of 260 extension officers and 29 crop inspectors on biological control methods,” she said.
According to Miller, the parasitoid has successfully established itself in Kenya’s coastal region, achieving over 70 per cent parasitism.
“In just one year, papaya production returned to pre-infestation levels,” she said, adding that the withdrawal of chemical pesticides by participating farmers led to the resurgence of natural predators and beneficial insects in affected areas.
She said a full socio-economic assessment conducted in March, following an initial baseline in 2019, showed that the biological control intervention increased papaya yields by 19 per cent and farmers’ incomes by 57 per cent.
Miller warned that the papaya mealybug poses a threat not only to a key cash crop but also to regional food security and biodiversity.
She emphasized that CABI’s integrated approach—combining science, farmer participation, gender inclusivity, and cross-border collaboration—demonstrates that sustainable solutions are achievable.
“With Acerophagus papayae proving to be a powerful ally, smallholder farmers in Kenya, Uganda, and South Sudan are turning the tide against one of the region’s most destructive invasive pests,” Miller said.
