Diversification in the use of resources by Idarnes species: bypassing functional constraints in the fig-fig wasp interaction

Abstract

Mutualisms such as the fig-fig wasp mutualism are generally exploited by parasites. We demonstrate that amongst nonpollinating fig wasps (NPFWs) parasitic on Ficus citrifolia, a species of Idarnes galls flowers and another species feeds on galls induced by other wasps killing their larvae. The galling wasp inserts its ovipositor through the fig wall into the fig cavity.The ovipositor then follows a sinuous path and is introduced through the stigma and style of the flower. The egg is deposited between the integument and nucellus, in the exact location where the pollinating mutualistic wasp would have laid its egg. Gall induction is a complex process. In contrast, the path followed by the ovipositor of the other species is straightforward: attacking a larva within a developed gall poses different constraints. Shifts in feeding regime have occurred repeatedly in NPFWs. Monitoring traits associated with such repeated evolutionary shifts may help understand underlying functional constraints.

Mechanisms of ovipositor insertion and steering of a parasitic wasp

“…The presence of multiple curves in single insertions indicates a degree of steering similar to that observed in previous studies on wasps (25,37). Furthermore, the insertion trajectory pattern in a probing session (Fig.…”

“…The second challenge during oviposition is that the wasps need to steer the ovipositor tip in the direction of the desired target (25). To do so, the ovipositor needs flexibility and a steering/bending mechanism that adjusts the tip direction during probing.…”

“…The proposed theories of probing are based on morphological data, with only a few studies focusing on the ovipositor inside the substrate (25,37), but no one has ever analyzed the dynamics of probing inside the substrate. In this work, we aim to quantify the ovipositor use (range, speed, and curvature of probing) in relation to substrate density and to determine which of the proposed methods of insertion and steering are used by parasitic wasps.…”

How to be a fig wasp parasite on the fig–fig wasp mutualism

“…The molecular mechanism of galling is completely uninvestigated; secretions of the poison gland may be involved [25]. Gallers, particularly the large gall inducers, may inject cytokine-like compounds that manipulate plant tissue as in other systems [26].Some NPFWs are kleptoparasites [27] incapable of inducing galls but ovipositing into existing galls; their larvae feed on galled tissue, starving the gall occupant. How such larvae out-compete existing gall inhabitants is unknown but is important to understand because developing fig wasps are confined to their own galls from which they must derive all nutrition [28 ].…”

Sistemática e biogeografia de besouros curculionídeos (Curculionoidea; Coleoptera) associados a figueiras (<i>Ficus</i>; Moracae)

“…Although they adopted diverse feeding strategies (Compton, 1993;Elias et al, 2012), these wasps generally have a long ovipositor that can be inserted from outside the fig through its wall, allowing them to compete with the pollinating wasps for female flowers (Cook & Rasplus, 2003). The intricate relationship between fig trees, pollinating wasps and nonpollinating-wasps have been largely scrutinized, showing that the syconium has a long history of diversification with an extremely diverse and specialized community of wasps (Kerdelhué et al, 2000;Jousselin et al, 2003;Weiblen, 2004;Cook & Segar, 2010;Cruaud et al, 2011).…”