Non-pollinating Fig Wasps Research Articles

Among us: How to find an optimal clutch sex ratio when the clutch sex ratios of co-foundress wasps are not known beforehand?

A female-biased clutch sex ratio is selected under local mate competition since it reduces competition between male sibs and provides extra mating opportunities for sons. Theoretical models predict that the brood sex ratio of fig wasps becomes less female-biased as the number of wasps laying eggs in the same fig increases. Empirical data have demonstrated that pollinator females lay most of their male eggs first, followed by the female ones in an oviposition bout (males first rule). As oviposition sites are limited in the fig, the brood sex ratio is positively correlated with the number of wasps laying eggs. To understand the strategy of sex ratio adjustment of Sycobia hodites, a non-pollinating fig wasp associated with Ficus benjamina, we compared observed and simulated data. The female wasp starts oviposition shortly after landing on the fig. This process involves the insertion of the ovipositor through the fig surface and into the flower's ovary via the stigma/style. The brood sex ratio of S. hodites did not significantly correlate with the fig brood size. Brood simulations supported the notion that the sex ratio of S. hodites is automatically determined by the male-first rule, involving no control by the mothers. The simulation model best fitting empirical data considered that: (1) females lay few eggs per fig (six or less) and distribute their eggs among several figs, and (2) the probability of an egg producing a male wasp decreases with its position in the egg sequence. Empirical and simulated data showed a wide variation in both brood size and sex ratio, suggesting that selection for an optimal clutch sex ratio is possibly weak. We argue that when selective pressure for sex ratio adjustment is weak, evolution favors male polymorphism as a strategy to cope with mate competition.

How to be a fig nematode

Fig (Moraceae: Ficus) species host vast communities of organisms that are bound together by complicated ecological networks that have influenced community structure and dynamics over evolutionary timescales. Much attention has been paid to the mutualism between figs and their specialized pollinating fig wasps, as well as with often antagonistic non-pollinating fig wasps. Equally ubiquitous to fig systems, but much less understood are the multitude of nematode groups that have independently evolved obligate associations with pollinating fig wasps and proliferate inside fig syconia. In this review we describe what is currently known (and unknown) about these numerous and increasingly studied nematode taxa and how they interact with the fig systems they inhabit. We identify the groups that are currently understood to associate with fig pollinators and outline their known species distributions and evolutionary history, where possible. Special attention is paid to the life history of these nematode groups, especially which features of nematode biology are generalizable across groups and what idiosyncratic peculiarities exist within individual genera. We outline key biological features including host choice, dispersal, disembarkation, diet, mating, and proliferation within figs. We address biological conundrums that have been raised following observational work such as, why do nematodes sometimes infect the wrong host? What adaptations were required for nematodes to successfully adapt and coexist with figs and their pollinators for millions of years? How do nematodes overcome the constraints of low mating group size? Finally, we outline key considerations, gaps in the knowledge, and limitations to expand this field forward towards promising areas of future research. Through better understanding of fig nematodes, we stand to not only know more about Ficus communities, but also more about the evolution and maintenance of interspecific interactions, development, adaptation, and co-evolution in general.

Parasitism Features of a Fig Wasp of Genus Apocrypta (Pteromalidae: Pteromalinae) Associated with a Host Belonging to Ficus Subgenus Ficus

Non-pollinating fig wasps (NPFWs), particularly long-ovipositored Sycoryctina wasps, exhibit a high species specificity and exert complex ecological effects on the obligate mutualism between the plant genus Ficus and pollinating fig wasps. Apocrypta is a genus of NPFWs that mostly interacts with the Ficus species under the subgenus Sycomorus, and the symbiosis case between Apocrypta and F. pedunculosa var. mearnsii, a Ficus species under subgenus Ficus, is unique. As fig's internal environments and the wasp communities are distinct between the two subgenera, we addressed the following two questions: (1) Are the parasitism features of the Apocrypta wasp associated with F. pedunculosa var. mearnsii different from those of other congeneric species? (2) Is this Apocrypta species an efficient wasp that lives in its unique host? Our observation revealed that this wasp is an endoparasitic idiobiont parasitoid, as most congeneric species are, but developed a relatively long ovipositor. Furthermore, the relationships of the parasitism rate versus the pollinator number, the fig wall, and the sex ratio of the pollinator, respectively, showed that it possessed a higher parasitism ability than that of other congeners. However, its parasitism rate was low, and thus it was not an efficient wasp in its habitat. This difference between parasitism ability and parasitism rate might be a consequence of its oviposition strategy and the severe habitat conditions. These findings may also provide insights into the mechanism to maintain the interaction between the fig tree and the fig wasp community.

Seven Sycoryctine Fig Wasp Species (Chalcidoidea: Pteromalidae) Associated with Dioecious Ficus hirta Inhabiting South China and Southeast Asia.

Simple SummaryThe non-pollinating fig wasps are essential components of fig wasp communities, negatively impacting mutualism. However, this group of fig wasps has received less taxonomic attention than pollinating fig wasps. This study presents seven new non-pollinating fig wasp species associated with Ficus hirta fig trees inhabiting South China and Southeast Asia. The presence of a long ovipositor sheath characterizes this group of fig wasps. An identification key is provided to distinguish between them, and the relationships with their host fig trees are discussed. The type specimens and examined materials are deposited in the South China Botanical Garden, Chinese Academy of Sciences, China.Even though non-pollinating fig wasps are essential components in tropical and subtropical habitats, yet they are poorly described in the Oriental communities. This study presented seven new sycoryctine fig wasp species associated with Ficus hirta fig trees inhabiting South China and Southeast Asia. These new sycoryctine species belong to the genera Philotrypesis, Sycoryctes, and Sycoscapter. They can be easily distinguished by their adaptive morphologies such as face sculpture, body-color, and ovipositors. An identification key is provided to differentiate between them, and the relationships with their host fig trees are also discussed. The holotypes and paratypes are both deposited in the South China Botanical Garden, Chinese Academy of Sciences, China.

Description of a new species of the genus Walkerella (Pteromalidae: Otitesellinae) from Kerala, India

ABSTRACT Walkerella is an Old World genus of non-pollinating fig wasps in the subfamily Otitesellinae (Chalcidoidea: Pteromalidae) with only nine known species worldwide. This paper describes one new species, Walkerella talboti Shilpa & Santhosh sp. nov., from Ficus talboti belonging to subsection Dictyoneuron of section Conosycea, subgenus Urostigma in Kerala, India. Available species level diagnostic key is supplemented to facilitate identification of both sexes of the new species. http://zoobank.org/urn:lsid:zoobank.org:pub:69216971-B68E-43EA-96AC-2D2F25B3D3C1

Genome-Wide Identification and Analysis of Lipases in Fig Wasps (Chalcidoidea, Hymenoptera).

Simple SummaryLipases are a large family of enzymes involved in lipid metabolism. Lipids play diverse roles in insect growth and responses to environmental stimuli. Fig wasps are a polyphyletic assemblage of Chalcidoidea that develop in the inflorescences of fig trees. Based on whether they can pollinate, they are separated into pollinator fig wasp (PFW) and non-pollinating fig wasp (NPFW). In this study, we conducted a genome-wide screening of lipases in the 12 fig wasp genomes using bioinformatics tools, including seven PFWs and five NPFWs. In total, 481 lipase genes were identified with the neutral and acid lipases as the most numerous families. NPFWs had significantly more lipases than PFWs. Tandem duplication accounted for the expansion of the gene family. Phylogenetic analysis indicated that the lipase genes were conserved. This study provided evidence of insect metabolism to understand the obligate mutualism between figs and fig wasps. Our results will facilitate the understanding of the molecular mechanism of how lipase proteins contribute to the distinctions of life histories between PFWs and NPFWs.Lipases are the main enzymes involved in lipid metabolism. However, the characteristics of lipases in insects were scarcely investigated. Here, we screened the recently sequenced genomes of 12 fig wasp species consisting of seven pollinator fig wasps (PFWs) and five non-pollinating fig wasps (NPFWs) for the six major lipase gene families. In total, 481 lipase genes were identified, and the two most numerous families were the neutral and acid lipases. Tandem duplication accounted for the expansion of the gene family. NPFWs had significantly more lipases than PFWs. A significant gene family contraction occurred in the clade of PFWs. The difference of lipases between NPFWs and PFWs might contribute to their distinction in life histories and feeding regimes. Phylogenetic analysis showed that the lipase genes of each fig wasp species was almost equally distributed in each clade, indicating that the lipase genes were conserved. The gene structures were similar within each clade, while they were different among clades. Most of the neutral and acid lipases were signal peptides and located extracellularly. The pathways of lipases involved were predicted. This genome-wide study provides a systematic analysis of lipase gene families in 12 hymenopteran insects and further insights towards understanding the potential functions of lipases.

Community structure and specialization in fig wasps (Hymenoptera: Chalcidoidea) in a region of Cerrado

Ficus inflorescences host a species-rich chalcid wasp community, including pollinating fig wasps (Agaonidae: Tetrapusinae, Kradibiinae, and Agaoninae) and several species of non-pollinating fig wasps (NPFW), that show several life-history strategies, including gall-inducers, kleptoparasites (i. e. inquilines), and parasitoids. We analyzed the structure and degree of specialization of the fig wasp community associated with Ficus inflorescences in urbanized areas, agroecosystems, and on the edge of forest fragments in the state of Goiás (Brazil). We sampled 34 wasp species in four native Ficus tree species, from which four wasp species occurred in more than one host. Neotropical fig pollinators (Pegoscapus and Tetrapus) were the most abundant species, and they were host-specific, although two pollinator species were associated with Ficus obtusifolia. The Jaccard similarity index was higher in samples of fig wasps collected in the same host, indicating that the community composition was specific to each host species. Community structure indices indicate a specialized structure with low connectance, high bidimensional Shannon H2’ and low partner diversity. The communities present a modular web structure in which modules were represented by each host and its associated insect species. These results indicate that the fig wasp communities analyzed are highly specialized, despite a few not strictly host-specific species.

Pollinating and non-pollinating fig wasps (Hymenoptera: Chalcidoidea) from Ficus elastica, the living root bridge tree of Meghalaya in northeast India

The Indian rubber fig tree Ficus elastica Roxb. ex Hornem. Moraceae is the constituent of the iconic living root bridges (LRBs) in Meghalaya, India, and is characterized by a highly specific mutualism between the fig and its pollinating agaonid fig wasp, in which the wasps breed within fig inflorescences. F. elastica is restricted to south and southeast Asia in its distribution. We identified the pollinating fig wasp as Platyscapa clavigera (Mayr 1885) which was first described from F. elastica in Bogor in 1885 and from Singapore in 2017. This is the first record of the pollinator (family Agaonidae) from F. elastica in Meghalaya, northeast India, in the westernmost portion of the fig’s range. We also discovered and identified in F. elastica, a non-pollinating fig wasp of the genus Micranisa which appears close to Micranisa ralianga Mathew and Balakrishnan 1981 (Pteromalidae). This fig wasp has not been earlier reported anywhere from the closed urn-shaped inflorescences (i.e. syconia) of F. elastica and was only described from the syconia of Ficus altissima Blume in 1981 from Meghalaya. Notes on the morphology of both fig wasps are provided and illustrated. The phenology and developmental cycle of F. elastica syconia are documented. Evidence of passive pollination was confirmed in F. elastica which sheds light on the evolution of character traits in figs and their wasps

Differential effects of nematode infection on pollinating and non‐pollinating fig wasps: Can shared antagonism provide net benefits to a mutualism?

Species pairs that form mutualistic associations are also components of broader organismal community networks. These interaction networks have shaped the evolution of individual mutualisms through interspecific interactions ranging from secondarily mutualistic to intensely antagonistic. Our understanding of this complex context remains limited because characterizing the impacts of species interacting with focal mutualists is often difficult. How is the fitness of mutualists impacted by the co-occurring interactive network of community associates? We investigated this context using a model interaction network comprised of a fig and fig wasp mutualist, eight non-pollinating fig wasp (NPFW) antagonists/commensals and a nematode previously believed to be associated only with the pollinator wasp mutualist. Through repeated sampling and field observations, we characterized the ecological roles of these mutualist-associated organisms to identify key antagonists. We then investigated how potential nematode infection of NPFWs could impact wasp survival across key life stages and, in turn, inferred how this influences the fitness of the fig-pollinator mutualists. Unexpectedly, we found all Ficus petiolaris-associated NPFWs to be the targets for nematode infection, with infection levels sometimes exceeding that of pollinators. Experimental data collected for the most abundant NPFW species suggest that nematode infection significantly reduces their longevity. Further, comparisons of nematode loads for emerging and successfully arriving NPFWs suggest that infection severely limits their dispersal ability. Through these observations, we conclude that this infection could impact NPFWs more severely than either mutualistic partner, suggesting a novel role of density-dependent facultative mutualism between figs, pollinator wasps and the nematode. This antagonist-mediated suppression of other network antagonists may present an ecologically common mechanism through which antagonists can present net benefits for mutualists' fitness.

Low host specificity and broad geographical ranges in a community of parasitic non-pollinating fig wasps (Sycoryctinae; Chalcidoidea).

Plants, phytophagous insects and their parasitoids form the most diverse assemblages of macroscopic organisms on earth. Enclosed assemblages in particular represent a tractable system for studying community assembly and diversification. Communities associated with widespread plant species are especially suitable as they facilitate a comparative approach. Pantropical fig-wasp communities represent a remarkably well-replicated system, ideal for studying these historical processes. We expect high dispersal ability in non-pollinating fig wasps to result in lower geographical turnover in comparison to pollinating fig wasps. The ability of non-pollinating wasps to utilise a number of hosts (low host specificity) is a key determinant of overall geographical range, with intraspecific competition becoming a constraining factor should diet breadth overlap among species. Finally, we expect conserved community structure throughout the host range. We aim to test these expectations, derived from population genetic and community studies, using the multi-trophic insect community associated with Ficus hirta throughout its 3,500km range across continental and insular Asia. We collect molecular evidence from one coding mitochondrial gene, one non-coding nuclear gene and multiple microsatellites across 25 geographical sites. Using these data, we establish species boundaries, determine levels of host specificity among non-pollinating fig wasps and quantify geographical variation in community composition. We find low host specificity in two genera of non-pollinating fig wasps. Functional community structure is largely conserved across the range of the host fig, despite limited correspondence between the ranges of non-pollinator and pollinator species. While nine pollinators are associated with Ficus hirta, the two non-pollinator tribes developing in its figs each contained only four species. Contrary to predictions, we find stronger isolation by distance in non-pollinators than pollinators. Long-lived non-pollinators may disperse more gradually and be less reliant on infrequent long-distance dispersal by wind currents. Segregation among non-pollinating species across their range is suggestive of competitive exclusion and we propose that this may be a result of increased levels of local adaptation and moderate, but regular, rates of dispersal. Our findings provide one more example of lack of strict codiversification in the geographical diversification of plant-associated insect communities.

Gene duplication and subsequent functional diversification of maltase in fig wasp (Chalcidoidea, Hymenoptera)

Maltase can catalyze the hydrolysis of α-1,4-glucosidic linkages and release α-d-glucoses that are used as a source of energy by insects. Maltase has been extensively studied in Lepidoptera and Diptera, while the characterization and evolutionary history of maltase are largely unknown in Hymenoptera. Here, we undertook a bioinformatics study and identified 105 maltase genes in 12 fig wasp species. Together with the maltase genes of Nasonia vitripennis and Apis mellifera, phylogenetic analysis showed that all the maltase genes were clustered into three clades. Clade I and III included maltase genes from all the fig wasp species, while clade II contained the maltase genes from non-pollinating fig wasps (NPFWs) only. Interestingly, the maltase genes located in clade II were intronless. Fig pollinators and NPFWs had lineage-specific gene expansion in clade I and II respectively, which were mainly derived from tandem duplications. The three clades displayed distinct gene structures. Furthermore, maltase showed significant functional divergence among the three clades and the critical amino acid sites were detected. These sites could be responsible for the ligand-binding preference and hydrolytic specificity. Overall, our results demonstrated that maltase might contribute to the discrepancy of life histories and feeding regimes between fig pollinators and NPFWs.

Genome-Wide Analysis of Chemosensory Protein Genes (CSPs) Family in Fig Wasps (Hymenoptera, Chalcidoidea).

Chemosensory proteins (CSP) are a class of acidic soluble proteins which have various functions in chemoreception, resistance and immunity, but we still have very little knowledge on this gene family in fig wasps, a peculiar insects group (Hymenoptera, Chalcidoidea) that shelter in the fig syconia of Ficus trees. Here, we made the first comprehensive analysis of CSP gene family in the 11 fig wasps at whole-genome level. We manually annotated 104 CSP genes in the genomes of the 11 fig wasps, comprehensively analyzed them in gene characteristics, conserved cysteine patterns, motif orders, phylogeny, genome distribution, gene tandem duplication, and expansion and contraction patterns of the gene family. We also approximately predicted the gene expression by codon adaptation index analysis. Our study shows that the CSP gene family is conserved in the 11 fig wasps; the CSP gene numbers in pollinating fig wasps are less than in non-pollinating fig wasps, which may be due to their longer history of adaptation to fig syconia; the expansion of CSP gene in two non-pollinating fig wasps, Philotrypesis tridentata and Sycophaga agraensis, may be a species-specific phenomenon. These results provide us with useful information for understanding the evolution of the CSP gene family of insects in diverse living environments.

An early gall-inducing parasitic wasp adversely affects the fitness of its host Ficus tree but not the pollinator

The fig tree-fig pollinator mutualism is one of the most tightly knit symbiotic systems. The research on the ecology of non-pollinators which exploit the mutualism without providing services to the host is very limited and conclusions about the role they play in the maintenance of this mutualism are full of contradictions. The non-pollinating fig wasps species are highly diverse in their feeding habit and ecological function, which may result in different consequences on the mutualism. Sycophaga testacea is an early-ovipositing galler hosted by Ficus racemosa, which is a potencial competitor to the pollinators as they use the same female flowers in the fig as their ovipositing sites. In this study, we investigate the effect of S. testacea on the production of both pollinator and fig tree with a field control experiment. Seed production is decreased significantly when the figs were parasitized, while the offspring production of the pollinator is not significantly affected, which indicates that this galler species has a harmful effect on the fitness of its host fig tree but not the pollinator. The overall development ratio of the galls is decreased significantly when the figs were parasitized, and we found that the intrinsic low development ratio of S. testacea is responsible for the decrease in the overall development ratio.

Community Structure and Undescribed Species Diversity in Non-Pollinating Fig Wasps Associated with the Strangler Fig Ficus petiolaris

Abstract Figs and their associated mutualistic and parasitic wasps have been a focus of intensive ecological and evolutionary research due to their diversity, unusual reproductive biology, and highly coevolved interspecific relationships. Due to the ecological dependence of their interactions, fig wasps were once considered to be fig-species specific and to cospeciate with their hosts, however, a growing body of evidence reveals mixed support for species specificity and the importance of additional evolutionary processes (e.g., host switching) structuring these long-term interactions. Our research on the genus Idarnes Walker, 1843 (Hymenoptera, Agaonidae), a common non-pollinating wasp of New World fig flowers, reveals a community in which multiple wasp species coexist on the same host in space and time. Using both molecular and morphological data, we identify five distinct Idarnes lineages associated with a single host fig species, Ficus petiolaris Kunth, 1817 (Rosales, Moraceae). A comprehensive phylogenetic analysis including Idarnes species from numerous host fig species reveals that the lineages associated with F. petiolaris do not form a monophyletic group but are distantly related, suggesting multiple independent colonization events and subsequent diversification. Morphological and ecological data provide support that the wasps are partitioning niches within the figs, explaining the coexistence of these diverse lineages on the same host fig. These results, coupled with a growing body of research on pollinating and non-pollinating fig wasps, bring into focus a more dynamic picture of fig and fig wasp coevolution and highlight how wasp lineage divergence and niche partitioning contributes to increased species diversity and community structure on a single fig host.

Fighting injuries, fig exit, and dimorphism in two species of sycoryctine fig wasp (Chalcidoidea, Pteromalidae)

Similar to many vertebrate and invertebrate species, many fig wasp species are fighting other members of their species for mates. Fighting between the males of many non-pollinating fig wasp species involves injuries and fatalities. Studies have shown that large males fight for mates, whereas conspecific small males tend to adopt nonfighting, sneaky behaviors. To analyze male morphs in two non-pollinating fig wasps (Philotrypesis taida Wong & Shiao, 2018 and Sycorycteridea taipeiensis Wong & Shiao, 2018) associated with the fig tree Ficus benguetensis, the head and mandible allometry and injuries were examined as well as the morphologies of their heads and mandibles. Male fig wasps of these two nonpollinating species can be divided into two morphological groups according to their head and mandible shapes. Approximately 88% of the Philotrypesis and 62% of the Sycorycteridea males were injured and no males belonging to largest morphs were decapitated. Moreover, nearly 31% of the Philotrypesis and 45% of the Sycorycteridea males left their natal figs. No difference in injury level or male exit rate between the male morphs was observed. This study reveals slight morphological and behavioral differences that may hint towards different mating strategies among morphs.

Complex effects of nonpollinating wasps on the relationship between pollinating wasp and seed production in Ficus andicola

Mutualisms are evolutionarily unstable because an imbalance in benefits obtained by the two partners may make the interaction exploitative. In the Ficus-Agaonidae system, it is advantageous for pollinating wasps (PW) to lay eggs in as many flowers as possible within a fig, to maximize offspring production. From the tree's perspective, however, a balance is expected between seed and wasp production, as wasps represent the tree's male function. The key to the system's stability requires explaining why PW mainly use internal flowers for egg-laying, leaving those closer to the fig's wall for seed production. An hypothesis proposes that nonpollinating fig-wasps (NPFW), which exploit the system by laying eggs in figs but not pollinating, help stabilize the mutualism. We compared seed and PW production in figs of F. andicola with and without NPFW. In unexploited figs, seed and PW numbers were negatively correlated, and the PW/seeds proportion was 3:1. In exploited figs, seed and PW numbers were positively correlated, and the PW/seed ratio was approximately 1:1. This pattern may result from an indirect effect of Idarnes gr. flavicollis on PW. This species of NPFW lays before or simultaneously with PW in the same kind of flowers, causing PW to spend more time searching for free ovaries, thus reducing their laying rate. Alternatively, PW may reject some flowers to reduce the risk of exploitation by NPFW. In unexploited figs, PW use more flowers at the expense of seed production. In exploited figs, NPFW restrict flower use by PW, favoring a balance in the seeds/PW ratio. This effect only occurs at low exploitation levels. The absence of NPFW favors PW, whereas high exploitation levels are detrimental for both seeds and PW. A high spatial and temporal variability in exploitation rates seems required to avoid directional selection favoring PW or NPFW, thus stabilizing the mutualism.

The unknown followers: Discovery of a new species of Sycobia Walker (Hymenoptera: Epichrysomallinae) associated with Ficus benjamina L. (Moraceae) in the Neotropical region

Biotic invasion in mutualistic communities is of particular interest due to the possible establishment of new relationships with native species. Ficus species are widely cultivated as ornamental plants, and they host specific communities of chalcid wasps that are strictly associated with the fig inflorescences. Some introduced fig species are capable of establishing new relationships with the local fig wasps, and fig wasp species may also be concomitantly introduced with their host plants. Ficusbenjamina L. is widely cultivated across the world, but the associated fig wasps are not reported outside of the species native range. We describe for the first time a non-pollinating fig wasp associated with F.benjamina inflorescences outside its native distribution. Sycobiahodites Farache & Rasplus, sp. n. is the third known species of the genus and was recorded in populations of F.benjamina introduced in the Neotropical region throughout several localities in Argentina, Brazil and Colombia. Sycobia is a gall-inducing non-pollinating fig wasp genus associated with fig trees in the Oriental and Australasian regions. This species competes with pollinators for oviposition sites and may hinder the future establishment of the native pollinator of F.benjamina, Eupristinakoningsbergeri Grandi, 1916 in the New World. However, the occurrence of a gall inducing species in this host plant may open ecological opportunities for the establishment of species belonging to other trophic levels such as cleptoparasite and parasitoid wasps.

HOW TO BE A GOOD NON-POLLINATING FIG WASP: GALLING WASPS (Idarnes group flavicollis) DO NOT INTERFERE WITH THE FLORAL RECEPTIVITY

Mutualistic relationships are open to exploitation by non-cooperative species that can reduce the fitness of one or both cooperating partners. In addition to their obligate agaonid pollinators, a diverse community of non-pollinating fig wasps (NPFW) also uses the figs as a resource for the development of their broods. Some species of NPFW are gall makers and compete with the pollinators for the same pool of pistillate flowers. We experimentally demonstrated that the oviposition of the galling wasp Idarnes sp. group flavicollis at the beginning of anthesis does not interfere with stigma receptivity or the fig attractiveness of Ficus citrifolia . However, in situations of high Idarnes sp. infestation, the time window during which pollinators can enter the figs is shortened approximately by half. The enlargement of the Idarnes gall compresses the ostiole bracts, leading to an early closing of the fig ostiole, although the figs are still attractive. This negative effect on fig pollination seems to be more important in severely fragmented habitats where heliophilous fig tree species such as F. citrifolia are more abundant, favoring population of NPFWs, making over-infestation more frequent.

Oogenesis and ovarian morphology in pollinating and non-pollinating fig wasps: evidence from adult and immature stages

Hymenopteran insects have meroistic polytrophic ovaries characterised by trophocytes associated with oocytes inside the follicles. In pro-ovigenic species, all oocytes mature before emergence and no trace of oogenesis is visible in adult females. Pro-ovigeny is a rare condition among Hymenoptera, but common in pollinating fig wasps. In the present investigation, we studied adult and pupa females of three fig wasp species with different trophic strategies. We demonstrated that females of Pegoscapus aerumnosus and Idarnes spp. have an unusual ovarian organisation (i.e. each ovariole has only one mature egg and no oocyte) that has led to misleading interpretation of fig wasp reproductive anatomy. The ovaries of these studied species have several ovarioles, recognisable by the presence of nuclei of tunica propria cells surrounding them. Each adult wasp ovariole had one mature egg. None of the pupae had mature eggs, but all of them had follicles with oocytes in different developmental stages. The studied fig wasps are pro-ovigenic, irrespective of their trophic strategy, since there were no signs of ovigeny in adult females. We discuss ecological and phylogenetic factors that could play a role in fig wasps reproductive strategies.

Figs, pollinators, and parasites: A longitudinal study of the effects of nematode infection on fig wasp fitness

Mutualisms are interactions between two species in which the fitnesses of both symbionts benefit from the relationship. Although examples of mutualism are ubiquitous in nature, the ecology, evolution, and stability of mutualism has rarely been studied in the broader, multi-species community context in which they occur. The pollination mutualism between figs and fig wasps provides an excellent model system for investigating interactions between obligate mutualists and antagonists. Compared to the community of non-pollinating fig wasps that develop within fig inflorescences at the expense of fig seeds and pollinators, consequences of interactions between female pollinating wasps and their host-specialist nematode parasites is much less well understood. Here we focus on a tri-partite system comprised of a fig (Ficus petiolaris), pollinating wasp (Pegoscapus sp.), and nematode (Parasitodiplogaster sp.), investigating geographical variation in the incidence of attack and mechanisms through which nematodes may limit the fitness of their wasp hosts at successive life history stages. Observational data reveals that nematodes are ubiquitous across their host range in Baja California, Mexico; that the incidence of nematode infection varies across seasons within- and between locations, and that infected pollinators are sometimes associated with fitness declines through reduced offspring production. We find that moderate levels of infection (1–9 juvenile nematodes per host) are well tolerated by pollinator wasps whereas higher infection levels (≥10 nematodes per host) are correlated with a significant reduction in wasp lifespan and dispersal success. This overexploitation, however, is estimated to occur in only 2.8% of wasps in each generation. The result that nematode infection appears to be largely benign – and the unexpected finding that nematodes frequently infect non-pollinating wasps – highlight gaps in our knowledge of pollinator-Parasitodiplogaster interactions and suggest previously unappreciated ways in which this nematode may influence fig and pollinator fitness, mutualism persistence, and non-pollinator community dynamics.