Data from:Parasites and investment to host inflorescences in a fig tree-fig wasp mutualism
Data files
Abstract
Most mutualisms are parasitized by third-party species that inflict costs on the mutualists. How such parasites affect mechanisms that help maintain mutualism stability is poorly understood, even in well-studied systems. Angiosperm plants tend to invest most resources in tissue that yields high net benefits. In mutualisms with plant hosts, a reduction in such investment can function as a key stability-promoting mechanism, such as in fig-wasp mutualisms. Here, uncooperative symbiont wasps that fail to pollinate incur ‘sanctions’ via reduced host investment to unpollinated figs, realized via fig abortion, killing all wasp offspring, or via elevated offspring mortality within unaborted figs. We experimentally exposed host Ficus racemosa figs to parasitic wasps Sycophaga fusca, which convert fig flowers into offspring without benefitting host trees, with or without uncooperative (pollen-free) or cooperative (pollen-laden) symbiont pollinator wasps Ceratosolen fusciceps. Pollen-free C. fusciceps were still able to convert fig flower ovaries into wasp offspring, whereas those naturally pollen-laden were prevented from reproducing by experimental manipulation. Independent of the effects of pollination and reproduction by pollinators, increased exposure to S. fusca parasites resulted in reduced rates of fig abortion and gall failure in unaborted figs. Although S. fusca converts flower ovaries that could otherwise become beneficial pollinator offspring or fig seeds into parasite offspring, figs with intermediate levels of parasite exposure received high levels of investment. Our results suggest that S. fusca parasite oviposition/larval activities can result in host trees boosting investment in figs, even when this may counter the tree’s interests. We suggest that oviposition/larval activity by these parasites may mimic the biochemical pathways of pollinator gall formation and seed production.
Dataset DOI: 10.5061/dryad.q83bk3jv5
Description of the data and file structure
This study shows that in the fig–wasp mutualism, parasitic wasps (Sycophaga fusca), which don’t benefit the host tree, can still trigger increased investment by the fig tree in developing figs. Surprisingly, this happens even when cooperative pollinators are absent, suggesting that the parasites may mimic signals usually produced by beneficial partners, potentially undermining the tree’s mechanisms for maintaining mutualism stability. All missing data indicated as NA.
Chen et al. 2025. Data sheet column headings: Column headings are the same for all three data sheets: Ex_1.csv, Ex_2.csv and Ex_3.csv, data for experiments 1, 2 and 3, respectively.
- Row – arbitrary row number. Data for each row are from a single fig.
- Treatment – experimental treatment to individual figs (see methods in publication for details).
- Tree – tree on which the experimental fig resided (see methods and Appendix s1. Table S1 for details).
- SF – the number of parasite wasps S. fusca to which each experimental fig was exposed.
- Poll – the number of C. fusciceps foundresses experimentally introduced into each fig.
- Pollen – whether experimental figs received pollen or not.
- SF_gall – whether flower ovary galling by parasites occurred or not
- Poll_gall – whether flower ovary galling by pollinator foundresses occurred or not.
- Abort – whether a fig aborted or not prior to maturity.
- Abortcode – binary code of whether a fig aborted (1) or not (0).
- N_SF_M – number of S. fusca male offspring produced in a fig
- N_SF_F – number of S. fusca female offspring produced in a fig
- N_pol_M – number of pollinator C. fusciceps male offspring produced in a fig.
- N_pol_F – number of pollinator C. fusciceps female offspring produced in a fig
- Galls – number of flowers in a fig converted into wasp galls (S. fusca + C. fusciceps).
- Seeds – number of seeds produced in a fig
- Vacant – number of flowers that failed to produce either a seed or to be converted into a wasp gall.
- Tot_flowers – total number of flowers within a fig
- Tot_SF – the total number of S. fusca offspring produced in a fig.
- Tot_poll – the total number of pollinator C. fusciceps offspring produced in a fig.
- Totwasps – the total number of wasps (S. fusca + C. fusciceps) produced in a fig.
- Gall_rate – the proportion of all flowers galled by wasps.
- Gall-failure – the proportion of all flowers galled by wasps that failed to produce an adult wasp offspring (see methods for details).
- Occupancy – the proportion of all flowers that were either galled by wasps or produced seeds (see methods for details).