Adaptations to hyperparasitism: Reviewing the evidence for evolutionary impacts of the 4th trophic level on primary parasitoids

Over the last several decades, much research has supported the hypothesis that parasitoids are important selective agents impacting host morphology, behavior, physiology, and life history. Mortality selection by primary parasitoids is believed to have resulted in an array of host adaptations to avoid, defend against, or resist parasitism, which have been particularly well studied in herbivorous lepidopteran and hemipteran hosts. An array of counter-adaptations in various species of primary parasitoids suggest that coevolutionary dynamics may be important in these systems. There is growing evidence indicating that parasitoids occupying the 4th trophic level (hyperparasitoids and pseudo-hyperparasitoids) exert similarly strong mortality selection on their primary parasitoid hosts, resulting in intriguing adaptations, including sequestration of secondary defenses from defended herbivorous hosts and 'host manipulation' (e.g., use of bodyguards) to minimize hyperparasitism. In this talk, I will use case studies to review the evidence supporting the selective impacts of hyperparasitoids on their 3rd trophic level hosts and highlight some potentially important differences in hyperparasitoid biology, including host specificity, body size plasticity, and life history strategies.