Source-sink dynamics assists the maintenance of a pollinating wasp.

Dispersal that unites spatially subdivided populations into a metapopulation with source-sink dynamics is crucial for species persistence in fragmented landscapes. Understanding such dynamics for pollinators is particularly urgent owing to the ongoing global pollination crisis. Here, we investigated the population structure and source-sink dynamics of a pollinating wasp (Wiebesia sp. 3) of Ficus pumila in the Zhoushan Archipelago of China. We found significant asymmetry in the pairwise migrant numbers for 22 of 28 cases on the historical timescale, but only two on the contemporary timescale. Despite a small population size, the sole island not colonized by a superior competitor wasp (Wiebesia sp. 1) consistently behaved as a net exporter of migrants, supplying large sinks. Comparable levels of genetic diversity, with few private alleles and low genetic differentiation (total Fst : 0.03; pairwise Fst : 0.0005-0.0791), were revealed among all the islands. There was a significant isolation-by-distance pattern caused mainly by migration between the competition-free island and other islands, otherwise the pattern was negligible. The clustering analysis failed to detect multiple gene pools for the whole region. Thus, the sinks were most probably organized into a patchy population. Moreover, the estimates of effective population sizes were comparable between the two timescales. Thus the source-sink dynamics embedded within a well-connected population network may allow Wiebesia sp. 3 to persist at a competitive disadvantage. This study provides evidence that metapopulations in the real world may be complicated and changeable over time, highlighting the necessity to study such metapopulations in detail.

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.

Conidarnes, a new oriental genus of Sycophaginae (Hymenoptera, Agaonidae) associated with Ficus section Conosycea (Moraceae).

The sycophagines are strictly associated with two subgenera of Ficus L. (Moraceae), namely Sycomorus and Urostigma. They mostly oviposit through the fig wall and lay their eggs within the fig flowers, being either gall-makers or parasitoids of other fig wasps. In this contribution, a new genus of Sycophaginae, Conidarnes Farache & Rasplus, gen. n., is described with seven new species: Conidarnes achterbergi Farache & Rasplus, sp. n.; Conidarnes bergi Farache & Rasplus, sp. n.; Conidarnes laevis Farache & Rasplus, sp. n.; Conidarnes santineloi Farache & Rasplus, sp. n.; Conidarnes subtectae Farache & Rasplus, sp. n.; Conidarnes sulcata Farache & Rasplus, sp. n.; and Conidarnes sumatranae Farache & Rasplus, sp. n. Illustrations, morphological diagnoses, dichotomous keys and multi-entry online keys to species are provided. Conidarnes species strictly occur in the oriental region, and their distribution does not overlap with the distribution of the two other genera belonging to the same clade. Due to their relative rarity, we encourage extensive sampling of Conosycea figs to improve our knowledge of the genus.

Revision of the Australasian genus Pseudidarnes Girault, 1927 (Hymenoptera, Agaonidae, Sycophaginae).

The species of Pseudidarnes are revised, and six species are described: P. acaudus Farache & Rasplus, sp. n.; P. astridae Farache & Rasplus, sp. n.; P. badiogeminus Farache & Rasplus, sp. n.; P. cooki Farache & Rasplus, sp. n.; P. kjellbergi Farache & Rasplus, sp. n.; P. laevis Farache & Rasplus, sp. n. Pseudidarnes minerva Girault, 1927 and P. flavicollis Boucek, 1988 are redescribed. A key to the species is provided as well as illustrations for all females and all known males (except the wingless male of P. minerva). We also provided further discussion on ecology, morphological patterns, and host taxonomy. Online dichotomous and multi-access interactive LUCID keys to all Pseudidarnes species are available at http://www.figweb.org/.

Pollinating fig wasp Ceratosolen solmsi adjusts the offspring sex ratio to other foundresses.

Local mate competition theory predicts that offspring sex ratio in pollinating fig wasps is female-biased when there is only one foundress, and increased foundress density results in increased offspring sex ratio. Information of other foundresses and clutch size have been suggested to be the main proximate explanations for sex ratio adjustment under local mate competition. Our focus was to show the mechanism of sex ratio adjustment in a pollinating fig wasp, Ceratosolen solmsi Mayr, an obligate pollinator of the functionally dioecious fig, Ficus hispida Linn., with controlled experiments in the field. First, we obtained offspring from one pollinator and offspring at different oviposition sequences, and found that offspring sex ratio decreased with clutch size, and pollinators produced most of their male offspring at the start of bouts, followed by mostly females. Second, we found that offspring sex ratio increased with foundress density, and pollinators did adjust their offspring sex ratio to other females in the oviposition patches. We suggest that when oviposition sites are not limited, pollinators will mainly adjust their offspring sex ratio to other foundresses independent of clutch size changes, whereas adjusting clutch size may be used to adjust sex ratio when oviposition sites are limited.