Exploration for olive fruit fly parasitoids across Africa - regional distributions and dominance of co-evolved parasitoids

The olive fruit fly, Bactrocera oleae , has been a key pest of olives in invaded regions Europe and North America. We conducted the largest modern exploration for the fly’s co-evolved parasitoids across Sub-Saharan Africa (Kenya, Namibia, and South Africa) and some of the fly’s expanded regions (Canary Islands, China, India, Morocco, Pakistan, Réunion Island and Tunisia). From Sub-Saharan regions, four native braconids, Psytallia lounsburyi , P. humilis , Utetes africanus and Bracon celer were collected. Principal Component Analysis showed that the regional dominance of these parasitoid species was related to climate niches, with P. lounsburyi the dominant species in the more tropical areas of Kenya, P. humilis dominant in the hot semi-arid areas of Namibia and U. africanus prevalent in Mediterranean climates of South Africa. Psytallia concolor was found in the Canary Islands, Moroccan and Tunisian, and the Afrotropical braconid Diachasmimorpha longicaudata in Réunion Island. In South Africa, seasonal monitoring of B. oleae showed consistently low infestation in unripe or ripe fruits. Multivariate analyses suggest that fruit maturity, seasonal climates and interspecific interactions shape the local parasitoid diversity that effectively regulates fly populations at low levels. The results are discussed with regard to ecological adaptations of co-evolved parasitoids, and how their adaptations impact biocontrol.