First record of an apparently rare fig wasp feeding strategy: obligate seed predation

Abstract

1. Fig trees require host‐specific agaonid fig wasps for pollination, but their figs also support numerous non‐pollinating fig wasps (NPFW) that gall fig tissues or develop as parasitoids. 2. Ficus microcarpa L. is widely naturalised outside its native range and the most invasive fig tree species. Seed predators are widely used for the biological control of invasive plants, but no obligate seed predatory (as opposed to ovule or fig wall galling) NPFW have been recorded previously from any fig trees. 3. Philotrypesis NPFW are usually regarded as parasitoids or ‘inquilines’ (parasitoids that also eat plant material) of pollinator fig wasps, but the present study provides evidence that Philotrypesis taiwanensis, a NPFW associated with F. microcarpa, is an obligate seed predator: (i) adults emerge from seeds of typical appearance, with a surrounding elaiosome; (ii) it shows no preference for figs occupied by fig wasp species, other than the pollinator; (iii) it only develops in figs that contain pollinated ovules, avoiding figs occupied by an agaonid that fails to pollinate; (iv) larvae are distributed in layers where seeds are concentrated and (v) it has a negative impact on seed but not pollinator offspring numbers. 4. Philotrypesis is a large genus, and further species are likely to be seed predators.

Host‐parasitoid relationships within figs of an invasive fig tree: a fig wasp community structured by gall size

“…Zhou et al ., ) and their known trophic diversity (e.g. Wang et al ., ), it is likely that some species are moderately flexible in their host relationships.…”

“…NPFW can be allocated into two trophic levels comprising phytophages with larvae that only feed on plant tissues and do not directly kill other fig wasps and parasitoids with larvae that develop at the expense of other species (Cook & Segar, 2010;Segar & Cook, 2012). Most species in Pteromalidae subfamilies Epichrysomallinae and Otitesellinae are believed to be gall formers, and Eurytomidae and Sycoryctinae (Pteromalidae) species are generally regarded as parasitoids of epichrysomallines and agaonids, respectively (Compton, 1993b;Segar & Cook, 2012;Suleman et al, 2013), but exceptions to broad taxonomic generalisations are likely (Pereira et al, 2007;Compton et al, 2009;Chen et al, 2013;Wang et al, 2014;Krishnan et al, 2015). Nevertheless, the exact extent of parasitoid host specificity within each fig wasp community associated with a particular fig tree is poorly understood.…”

Insect responses to host plant provision beyond natural boundaries: latitudinal and altitudinal variation in a Chinese fig wasp community

“…Philotrypesis taiwanensis Chen (Sycoryctinae) is the only obligate seed predator (Wang et al. ). In our analyses, we grouped the species associated with F. microcarpa into two trophic levels based on their feeding behavior: “phytophages” with larvae that feed exclusively on plant ovules or seeds and “parasitoids” with larvae that kill other fig wasp species.…”

“…Generally, species from subfamily Epichrysomallinae (family Pteromalidae) are the hosts of species from family Eurytomidae, and species from subfamily Sycoryctinae (family Pteromalidae) are parasitoids of both agaonids and species from subfamily Otitesellinae (family Pteromalidae). Philotrypesis taiwanensis Chen (Sycoryctinae) is the only obligate seed predator (Wang et al 2014). In our analyses, we grouped the species associated with F. microcarpa into two trophic levels based on their feeding behavior: "phytophages" with larvae that feed exclusively on plant ovules or seeds and "parasitoids" with larvae that kill other fig wasp species.…”

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

“…Only small-sized parasite males emerged from these seeds [29] indicating that seeds are not an adequate developmental resource. In another fig species which sustains a functional pollinator and a closely related cheater non-pollinator, obligate seed-eating NPFWs developed mostly within syconia occupied by the functional pollinator since only those syconia produced seeds [30].…”