Biogeographic Distribution and Host Specificity of Hymenopteran Parasitoids of Tephritids (Diptera) Infesting Mangoes in Cameroon, Central Africa

Tephritid fruit flies (Diptera) represent a major threat to mango production and food security across Sub-Saharan Africa. Up to date, the species diversity and ecological roles of their natural enemies remain underexplored. This study provides the first comprehensive analysis of hymenopteran parasitoid communities associated with tephritids infesting mangoes in two agroecological zones (AEZs) of Cameroon: the Sudano-Sahelian savannah (AEZ 1) and the High Guinean savannah (AEZ 2). From 2,795 mangoes sampled between 2020 and 2021 across seven orchards, a total of 27,654 tephritids (representing four species) and 1,008 parasitoids (belonging to six species from three families) adults emerged. A marked biogeographic partitioning of parasitoid communities was observed: Braconidae (Fopius caudatus, Diachasmimorpha fullawayi, Psyttalia concolor) were exclusively recorded in AEZ 1, particularly in the orchard of Lagdo which belong to the dry zone, whereas Figitidae (Ganaspis sp., Ealata saba) and Diapriidae (Trichopria sp.) dominated in the more humid AEZ 2 orchards. Notably, Ganaspis sp. was found in both AEZs. Host specificity varied: Ganaspis sp. and Trichopria sp. exhibited a broad host range, primarily parasitizing Bactrocera dorsalis, while E. saba showed a high specificity for Ceratitis cosyra. Importantly, the exotic parasitoid Fopius arisanus, previously introduced as a biological control agent, was not detected. Parasitism rates were high in cultivar with thin pericarp (e.g., ‘Palmer’). However, in Djefatou and Ngong (AEZ 1), premature fruit harvesting for livestock feed limited parasitism assessment, as fruits were removed from the orchards before parasitoid infestation could occur. These findings underscore the importance of managing indigenous parasitoids through the selection of suitable ecological conditions and plant resources. Indeed, elucidating host-parasitoid dynamics, as demonstrated in this study, could support the development of practical and sustainable strategies for mango pest management in Central Africa.