Moderate parasitoidism on pollinators contributes to population oscillations and increases species diversity in the fig-fig wasp community

Whether species diversity contributes to the ecosystem stability has been one of the most heated arguments in community ecology. Potentially different contributions of different ecosystem species have not been explicitly taken into account. With fig species and their associated fig wasp community as model system, we bring community structure into the “diversity-stability” debate by establishing the fig-fig wasp food web model. The simulations of our model indicated that wasp diversity was promoted by population density of the parasitoids of the pollinating wasps, and that top-down control from the parasitoids regulated community diversity and stability. Moreover, only moderate parasitoidism on the pollinators resulted in the regular/irregular oscillatory coexistence in the fig-fig wasp community. Increases in the wasp diversity could increase community stability when biodiversity of fig wasps was low, while population chaos would maintain wasp diversity in the fig-fig wasp system. Our theoretical predictions are consistent with the newest experimental study on the fig-fig wasp system, which showed that loss of top-down control (parasitoidism on the pollinators) resulted in a change in the balance of reciprocal benefits, thereby changing food web complexity.