Relation between two non-pollinating wasps oviposition and the fruit abscission on Ficus racemosa

In the fig-fig wasp obligate mutualism, parasitic wasps Platyneura testacea and Platyneura mayri coexist with pollinating wasps. Theses non-pollinating wasps only use the seeds of figs or compete with pollinating wasp for floral resources, bring no any benefits to figs. The parasitism of these non-pollinating wasps may result in the disruption of the cooperation between figs and fig wasps. The fruit abscission mechanism of plant is generally considered as one of the key factors maintaining system stability. However, our quantitative experiment and field observations of fig-fig wasp system showed that the figs did not abscise fruits oviposited by Platyneura mayri, but abscised fruits over-ovipisited by P. testacea. The observation showed that tree oviposited by more P. testacea will have higher proportion of abscission. The over- ovipositing of P. testacea is the main reason for selective abscission of syconium. Our results indicate that the plant can only abscise fruits oviposited by parasitic wasps before pollinating wasps in fig-fig wasp mutualism, but do not abscise the fruits parasitized by wasps ovipositing simultaneous or later than pollinating wasps, implying that abscission can not sufficiently maintain the fig-fig wasp mutualism.