Seed and Wasp Production in the Mutualism of Figs and Fig Wasps

Figs (Moracea: Ficus) and fig wasps (Hymenoptera: Chlocloids: Agaonideae) depend on each other to complete their reproduction. Monoecious fig species and their pollinating wasps are in conflict over the use of fig ovaries which can either produce one seed or one wasp. From observation on Ficus virens Ait., we showed that female flowers with outer layer of ovaries (near to the wall of syconium) had no significant difference from that with inner and interval layer of ovaries (near to the syconium cavity), in which most seeds and wasps were produced. This meant that fig tree provided the same potential resource for seed and wasps production. Observation indicated that there was usually only one foundress in syconium at female flower phase and no com- petition pollinators. Measurement of the style length of female flowers and the ovipositor of pollinators indicated that most ovaries could be reached by pollinator’s ovipositor. However, at the male flower phase, production of seeds was significantly more than that of wasps including non-pollinating wasps but there was no significant difference between seed and pollinating wasp production when without non-pollinating wasps produced. This result indicated that non-pollinating wasps competed ovaries not with seeds but with pollinating wasps for ovipositing. Bagged experiment showed that the sampling fig species was not self-sterile which was important for figs and wasps to survive bad season. Seed production in self-pollinated figs was not significantly different from total wasps in- cluding non-pollinating ones. This might be related with the weaker competition among wasps since bagged figs were not easy to reach by wasps from outside.

Disturbance effects on community structure of Ficus tinctoria fig wasps in Xishuangbanna, China： Implications for the fig/fig wasp mutualism

Fig trees are important components of tropical forests, because their fruits are eaten by so many vertebrates, but they depend on pollinating fig wasps to produce mature fruits. Disturbance to habitat structure can have a major impact on insect diversity and com- position, potentially reducing fruit yields. We investigated the impact of habitat disturbance on the fig wasp community associated with male figs ofFicus tinctoria in Xishuangbanna, China. The community comprised one pollinator species Liporrhopalum gibbosae and six non-pollinating wasp species： Sycoscapter sp. 1, Philotrypesis ravii, Philotrypesis sp. 1, Neosycophila omeomorpha, Sycophila sp.1, and Walkerella sp.1. More disturbed areas were characterized by higher temperatures, less shade, and more vehicle noise. The response of the fig wasp community was complex, with no simple relationship between intensity of disturbance and pollinator abundance. However, the sex ratios （proportion of male progeny） of pollinators increased significantly in more disturbed areas. We conclude that potential changes in fig wasp community composition brought about by disturbance, are unpredictable, with unclear consequences for tropical rainforest biodiversity.

Ultrastructural analysis of sperm from the genus Idarnes(Hymenoptera:Chalcidoidea,Sycophaginae)

In this study,the sperm ultrastructure of three species of Idarnes genus was investigated using light and transmission electron microscopy.Spermatozoon morphology of the three species was similar to that of most Chalcidoidea,with helicoidally twisted nucleus and flagellum.The head region consists of an acrosome and a nucleus;the nucleus-flagellum transition region characterized by the presence of mitochondrial derivatives and the centriolar adjunct;a flagellum region,which includes the axoneme with microtubular arrangement 9+9+2 and two mitochondrial derivatives.However,the sperm of these three species exhibit features that discriminate one species from each other:(1)only one species,Idarnes sp.2(carme group)exhibited an extracellular sheath surrounding the anterior portion of the nucleus,which extends to the anterior region of the flagellum,but it did not present filaments;(2)the acrosome in the three species was quite different,Idarnes sp.1 and Idarnes sp.2(carme group)has two compartments(acrosomal and subacrosomal vesicles)while Idarnes sp.3(flavicollis group)has a third compartment(perforatorium);(3)the centriolar adjunct elongated and its location among the mitochondrial derivatives is similar for the three species analyzed;(4)mitochondrial derivatives differ between the species,with triangular(Idarnes sp.1 and sp.3)and elongated or flat shaped(Idarnes sp.2)appearance.These data shows that sperm structure may differ within the same genus and confirms the potential of these cells in phylogenetic and taxonomic analyses in the Chalcidoidea superfamily,as well as in Hymenoptera in general.

High incidences and similar patterns of Wolbachia infection in fig wasp communities from three different continents

Wolbachia are endosymbiotic bacteria that infect numerous arthropod species. Previous studies in Panama and Australia revealed that the majority of fig wasp species harbor Wolbachia infections, but that similar patterns of incidence have evolved inde- pendently with different wasp species and Wolbachia strains on the two continents. We found Wolbachia infections in 25/47 species （53%） of fig wasp associated with 25 species of Chinese figs. Phylogenetic analyses of Wotbachia wsp sequences indicated that very similar strains are not obviously found in either closely related or ecologically linked fig wasps species. The extremely high prevalence of Wolbachia in fig wasps （over 50% of species infected） is not constrained by geographical origin and is a recurrent theme of fig wasp/Wolbachia interactions.

Fragmentation Effects on Diversity of Wasp Community and Its Impact on Fig／Fig Wasp Interaction in Ficus racemosa L.

Abstract: Habitat fragmentation usually results in alteration of species composition or biological communities. However, little is known about the effect of habitat fragmentation on the fig/fig wasp system. In this study, we compared the structure of a fig wasp community and the interaction between figs and fig wasps of Ficus racemosa L. in a primary forest, a locally fragmented forest and a highly fragmented forest. Our results show that, in the highly fragmented forest, the proportion of pollinator wasps is lower and the proportion of non-pollinator wasps is higher compared with the primary forest and locally fragmented forest. The proportion of fruits without pollinator wasps in mature fruits is also greatly increased in the highly fragmented forest. The proportion of galls in all female flowers increases in the highly fragmented forest, whereas the proportion of viable seeds does not change considerably. The disruption of groups of fig trees results in a decrease in pollinator wasps and even might result in the extinction of pollinator wasps in some extreme cases, which may transform the reciprocal interaction between figs and fig wasps into a parasite/host system. Such an effect may lead to the local extinction of this keystone plant resource of rain forests in the process of evolution, and thereby, may change the structure and function of the tropical rain forest.

Isolation of microsatellite loci in the pollinating fig wasp of Ficus hispida, Ceratosolen solmsi

Microsatellite loci were isolated for Ceratosolen solmsi, pollinator of the dioecious Ficus hispida. We developed nine polymorphic microsatellite loci based on the method of polymerase chain reaction isolation of microsatellite arrays （PIMA）. Enrichment of genomic libraries was performed by random amplified polymorphic DNA （RAPD）. A subset of 38 positive clones was sequenced; 15 clones showed microsatellite loci. We tested 15 designed primer pairs and nine of them produced polymorphic amplification in 48 individual wasps collected from different fruits of the dioecious host fig Ficus hispida in China. Among the 48 individuals, 49 alleles were obtained at the nine loci. The observed heterozygosity ranged between 0.357 and 0.634.

N:P stoichiometry in Ficus racemosa and its mutualistic pollinator

Aims Nitrogen(N)and phosphorus(P)are limiting nutrients to life across a variety of ecosystems.N:P stoichiometry,concerning the balance of these two elements,has recently received great attention.However,little is known about the nature of N:P stoichiometry in obligate mutualism.Methods N:P stoichiometry of Ficus racemosa and its pollinating wasp Ceratosolen fusciceps,an example of coevolving obligate mutualism,was investigated,and the N:P stoichiometric traits of male versus female wasps were compared.Important Findings Nutrient concentrations in C.fusciceps were much higher than in its host.N enrichment in fig wasp was evidently stronger than phosphorus.N concentrations of male fig wasps were significantly higher than those of females,while P concentrations of female fig wasps were remarkably higher than those ofmale ones.Therefore,N:P ratios inmale fig wasps were significantly greater than in female fig wasps.N:P ratio in fig-pollinating wasp displayed linear functions to fig N contents,suggesting that N limitation in fig wasps may dominate the nutritional relationship between fig pollinator and its host.Fig wasp population size had significant influences on N concentrations in host fig and female wasp per se.Driven by the nutritional stress of pollinating and parasite insects,fig fruit preferred increasing its diameter first but not nutrient richness.Values forNand P contents of fig pollinators showed seasonal differenceswith greater N:P ratios in dry season than in rainy season.The observations suggest that tropical climate change would result in more severe N limitation to fig-pollinating wasp and may further influence the stability of fig–fig wasp mutualism.