Pollination syndrome of the African custard apple (Annona senegalensis Pers.) reveals reliance on specialized brood-site weevil pollinators in Annonaceae

The pollination syndrome of the African custard apple (Annona senegalensis Pers.; Annonaceae) was investigated to gain insights into reproductive strategy this multipurpose wild shrub. Flower visitors were collected and frequently surveyed in morning on 30 flowers plants per site, at four sites across Sudanian Sudano-Sahelian climatic zones Burkina Faso during flowering season, from May June. A total nine species insects including Coleoptera (Curculionidae, Scarabeidae), Hymenoptera (Formicidae) Diptera (Tephritidae) observed visiting flowers. Among recorded insects, two sympatric weevil (Curculioninae, Ochyromerini, Endaeus castus Schoenherr floralis Marshall) by far most abundant (97% specimens) all 120 sampled. Both fleshy petals cantharophilous Annona that they use as substrate for development larval stages. These observations echo with ever-growing number researches highlighting major role weevils pantropical Annonaceae. Our study provides first evidence brood-site mutualism between an Annonaceae its specialized pollinators.