Post‐harvest disinfestation of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) in mango using hot‐water treatments

Abstract

AbstractMango, Mangifera indica L. (Anacardiaceae), is one of the most important fruits in Africa, providing household nutrition and economic development opportunities for millions of growers across the continent. In Kenya, over 80% of mango production is carried out by smallholders who produce this crop for both the domestic and the export markets. Despite its importance, mango production is hampered by several constraints, including infestation by fruit flies, especially the exotic Bactrocera dorsalis. In addition to its direct damage to fruits, the high quarantine status of the pest restricts the export of fruits and limits access to lucrative markets, impacting negatively on export earnings. To facilitate access to export markets, post‐harvest management measures such as hot‐water treatment are required to ensure quarantine security. Internationally, this level has been set as either 99.99% (Probit 8.7) or 99.9968% (Probit 9). In developing a protocol, the development of immature life stages of B. dorsalis in ‘Apple’ mango was established. Using this information, infested mangoes harbouring the different immature life stages were subjected to a hot‐water treatment of 46.1°C for four different times, and the egg mortality and larval mortality were determined. The third‐instar life stage was the most heat tolerant, followed by second‐ and first‐instar larvae and the egg stage, respectively. The immersion time of 81.47 min (95% CL 75.77–87.18) was established as the time required to achieve 99.99% security level. In the validation experiment, there were no survivors from the 51,101 third‐instar individuals treated in ‘Apple’ mango weighing 400–500 g. Furthermore, there were no survivors from the 44,651 third instars exposed to 46.1°C for 68 min. These results provide sound evidence that the shorter treatment duration is an effective post‐harvest disinfestations treatment against B. dorsalis, and should facilitate access to export markets for mango fruits from Africa.