Unleashing nature's defenders: Farmer-managed natural enemies field reservoirs (NEFRs) enhance management of the invasive papaya mealybug (Paracoccus marginatus) in coastal Kenya

Abstract

The papaya mealybug (PMB), Paracoccus marginatus, infests a wide range of plant species, including economically important crops, like papaya, citrus, cassava, and avocado, leading to significant economic losses. The parasitoid, Acerophagous papayae has been shown to manage the pest and was introduced in three coastal counties of Kenya from 2021. Natural Enemies Field Reservoirs (NEFRs), a technology that serves as in-situ production of A.papayae, were established in farmers’ fields in the three counties to assess their effectiveness in controlling the papaya mealybug in Kenya. Three treatments were set up including a. ‘No prior A. papayae release + NEFR’, b. ‘Prior A. papayae release + NEFR’, and c. ‘Prior A. papayae release but no NEFR’ (control). PMB populations decreased by 49.12 % and 62.8 % in treatments a and b, respectively, but increased by 37.6 % in the control. On the other hand, the absolute count of A. papayae increased by 456 %, 190 % and 51.6 % in treatments a, b and c, the control, respectively. Consequently, the parasitism rates increased by 116.7 % and 17.8 % in treatments a, and b, respectively but declined by 10.3 % in the control. The most abundant predators out of ten recovered genera were Cryptolaemus montrouzieri (44.0 %), Tenuisvalvae notata (23.9 %) and Exochomus sp. (19.9 %). The highest abundance and diversity of predators was recorded in treatment b ‘Prior A. papayae release + NEFR’ and the least abundance and diversity in the control. This study sheds light in the critical role of NEFRs in the management of PMB and its underscored potential as an effective, low-cost, farmer managed technology is discussed.