The long-term and transient implications of multiple predators in biocontrol

Abstract

In this study, we explore the role of multiple predators on the transient and long-term dynamic outcomes of biological control. Consistent with previous theory, our results suggest that specialist predators ought to promote less stable long-term biological control than generalists, while generalists readily drive suppression of nontarget prey species. Interestingly, our results show that the combination of specialists and generalists act synergistically to promote well-behaved biological control. This occurs because generalists do not as readily drive nontarget suppression in the presence of specialist, as specialists shunt energy away from generalists, lowering generalists’ growth rates and so lessening their impact on nontarget species. Similarly, specialists have a less destabilizing (i.e., less variable) influence in the presence of generalists, as generalists shunt energy away from specialists, reducing their growth rates and muting boom and bust dynamics. Finally, our results suggest the intriguing potential that endemic generalist predators, not introduced generalist predators, may often be responsible for the suppression and elimination of nontarget species. This final result demands empirical attention.