Kenya Steps Up Action against Papaya Pest

By Bellah Conte

In an effort to fight the devastating papaya mealybug infestation in Kenya, authorities are planning to roll out small parasitic wasps in Machakos, Makueni, Tharaka Nithi and Embu counties.

The release of these wasps is part of a collaborative initiative involving the Centre for Agriculture and Bioscience International (CABI), the Kenya Agricultural and Livestock Research Organisation (KALRO), the National Museums of Kenya, and Kenya Plant Health Inspectorate Services (KEPHIS).

The wasp,  Acerophagus papayae, destroys the pest, which resembles cotton-like masses, by laying its eggs on it.

Studies have shown that more than half of Kenya has been invaded by papaya mealybug and its impact has led some papaya farmers to abandon farming the fruit altogether. CABI, KALRO and KEPHIS have seen crop losses ranging from 53-100% and economic losses of 2,224/ha annually.

“The papaya mealybug is a significant pest which can devastate a whole crop if left unmanaged. This not only has a severe impact on the livelihood of a smallholder farmer but also the ability to contribute to local, national and global food security,” Dr Ivan Rwomushana, Senior Scientist, Invasive Species Management at CABI, said.

“It is hoped that following the releases of A. papayae, Natural Enemies Field Reservoir (NERF) technology, pioneered by the late CABI scientist Riaz Mahmood in Pakistan, will also prove fruitful in mass-rearing the parasitoid against papaya mealybug in Kenya.”

Before the release, the efficiency of A. papayae was evaluated under controlled laboratory conditions. The parasitic wasp demonstrated a high level of parasitism, with rates of 77.5%, 72.5%, and 47.5% in adult females, third, and second instars, respectively.

Following these findings, a dossier on the laboratory performance of the parasitoid was submitted to the Kenya Standing Committee on Imports and Exports for approval before its field release.

Additionally, the successful implementation of Natural Enemies Field Reservoir (NERF) technology, pioneered by the late CABI scientist Riaz Mahmood in Pakistan, is anticipated in mass-rearing the parasitoid to combat the papaya mealybug in Kenya.

There are plans for future releases of these waps in other papaya-growing counties, such as Meru, Murang’a, Kitui, Homabay, Busia, and Baringo, to ensure comprehensive coverage across the ten major papaya-producing regions in Kenya.