The spotted wing drosophila, Drosophila suzukii Matsumura, is an insect pest of soft-skinned fruit, native to Eastern Asia. Since 2008, a world-wide dispersal of D. suzukii is seen, characterized by the establishment of the pest in many Asian, American and European countries. While the potential for invasion of continental Africa by D. suzukii has been predicted, its presence has only been shown for Morocco in Northern Africa. Knowledge about a possible establishment in other parts of the continent is needed as a basis for pest management. In 2019, we carried out a first survey in three counties in Kenya to monitor for the presence of D. suzukii using traps baited with a blend of apple cider vinegar and red wine. A total of 389 D. suzukii flies were captured in a fruit farm at Nakuru county, with more female flies being trapped than males. We confirmed the morphological identification of D. suzukii using DNA barcoding. In 2020, we performed a follow-up survey at 14 locations in six counties to delimit the distribution of D. suzukii in the main berry growing zones in Kenya. The survey indicated that so far D. suzukii is restricted to Nakuru county where it was initially detected. This is the first study to provide empirical evidence of D. suzukii in continental sub-Saharan Africa, confirming that the pest is expanding its geographic range intercontinentally. Given the high dispersal potential of D. suzukii, a concerted effort to develop management strategies is a necessity for containment of the pest.

The braconid wasp, Diachasmimorpha longicaudata (Ashmead), was introduced in Kenya from Hawaii for classical biological control of the invasive tephritid, Bactrocera dorsalis Hendel. Following reports that D. longicaudata had formed new associations with Ceratitis cosyra, laboratory experiments were conducted to assess the interaction between the introduced and the native parasitoid of C. cosyra; Psyttalia cosyrae (Wilkinson) under three scenarios: B. dorsalis only, C. cosyra only and mixed populations of the two species. Parasitoids were introduced to the host as sole, sequential and simultaneous releases. Host searching and probing events were five times higher for D. longicaudata than P. cosyrae with both hosts. Total parasitism was highest (78%) when D. longicaudata was released alone on C. cosyra, compared to 20% for P. cosyrae released on the same host. Releases of P. cosyrae on B. dorsalis resulted in 0% parasitism, compared to 64% parasitism by D. longicaudata. Specific parasitism for P. cosyrae was three times higher when P. cosyrae was released first in sequential releases on C. cosyra compared to when it was released after D. longicaudata. These findings suggest that the two parasitoids can both suppress C. cosyra but B. dorsalis acts as a reproductive sink for P. cosyrae. Our findings should form the basis of field investigations where options are much wider for both parasitoids.

Mango, 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.

No abstract