species’ initial parasitism rates was not sufficient to predict their changes in abundance (Fig. 5f, Supplementary Table 10), but rather the predictions based on apparent competition were necessary. Summary of most important results We found that for each host species in the community, we could predict both the final parasitism rate, and with even greater accuracy, the change in abundance between time steps for that species. This prediction required information on the initial parasitism rate for that species, the extent to which that host species shares parasitoids with ‘normal’ all other host species in the region, plus the change in abundance between time steps of other host species. These predictions could equally be made for hosts in either native forest or adjacent exotic plantation forest, and for large or small changes in abundances of other host species in the system. These predictions even held when they were made for hosts in one habitat, but based only on data from the other habitat, regardless of whether the host’s habitat was native or plantation forest. Discussion Our finding that apparent competition is a structuring force strong enough to determine up to 31% of the variation in forest herbivore abundances has great potential utility in biological control and invasive species management, which often face poor predictive ability due to indirect effects among species26. Both these fields face the challenge of predicting potential impacts of introduced species or control agents before their arrival or release30,31. Our results show that apparent competition is an important
species’ initial parasitism rates was not sufficient to predict their changes in abundance (Fig. 5f, Supplementary Table 10), but rather the predictions based on apparent competition were necessary. Summary of most important results We found that for each host species in the community, we could predict both the final parasitism rate, and with even greater accuracy, the change in abundance between time steps for that species. This prediction required information on the initial parasitism rate for that species, the ‘normal’ extent to which that host species shares parasitoids with all other host species in the region, plus the change in abundance between time steps of other host species. These predictions could equally be made for hosts in either native forest or adjacent exotic plantation forest, and for large or small changes in abundances of other host species in the system. These predictions even held when they were made for hosts in one habitat, but based only on data from the other habitat, regardless of whether the host’s habitat was native or plantation forest. Discussion Our finding that apparent competition is a structuring force strong enough to determine up to 31% of the variation in forest herbivore abundances has great potential utility in biological control and invasive species management, which often face poor predictive ability due to indirect effects among species26. Both these fields face the challenge of predicting potential impacts of introduced species or control agents before their arrival or release30,31. Our results show that apparent competition is an important
NCOMMS-16-01466B_main%20text_AMK_CFFinal.docx