The impact of fig wasps (Chalcidoidea), new to the Mediterranean, on reproduction of an invasive fig tree Ficus microcarpa (Moraceae) and their potential for its biological control

Abstract

Natural enemies that reduce plant reproductive success are often utilized for biological control of invasive species. Reproduction in fig trees depends on host-specific fig wasp pollinators that develop in galled ovules, but there are also many species of non-pollinating fig wasps (NPFWs) that reduce seed and pollinator numbers. Fig wasps associated with an invasive Asian fig tree, Ficus microcarpa (Moraceae), were surveyed around the Mediterranean. Eight NPFW species are now known from the area, three of which are newly-recorded. The impacts of the two most prevalent ovule galling NPFW species (both Pteromalidae, Epichrysomallinae) on the tree’s reproduction were compared: Odontofroggatia galili Wiebes is widely-introduced, whereas Meselatus bicolor Chen has not been recorded previously outside its native range. Both gall-forming NPFWs significantly reduce seed and pollinator production, but M. bicolor has a far greater impact, entirely preventing seeds and pollinators from developing in the figs it occupies. M.bicolor has only been recorded from F. microcarpa and has the potential to be a valuable biological control agent in other countries outside the Mediterranean where F. microcarpa has become invasive.