Native generalist natural enemies and an introduced specialist parasitoid together control an invasive forest insect

Specialized natural enemies have long been considered a major force driving the population dynamics of outbreaking forest insects. While research has traditionally focused on the role of specialist parasitoids, recent studies and reviews reflect an appreciation of complex interactions among many regulatory factors. The sources suggest that specialist parasitoids and generalist predators can each inflict strong top‐down effects and that specialists and generalists can interact to regulate insect herbivore populations. Here we use the model study organism winter moth (Operophtera brumata) in its invasive range in the northeast United States to investigate interactions between the introduced, host-specific tachinid parasitoid Cyzenis albicans and native, generalist pupal predators. Prior research in Canada showed that predation of winter moth pupae increased after C. albicans establishment. To explain this phenomenon, the following hypotheses have been suggested: (1) parasitoids suppress t...