Coincidental intraguild predation among natural enemies of a key pest of tomato crop

Abstract

Studying how natural enemies interact within a tri-trophic system is fundamental to understand the mechanisms that promote coexistence and community stability. Coincidental intraguild predation (IGPc)—where predators consume prey parasitized by parasitoids—can disrupt trophic structure and compromise parasitoid persistence. Yet, the extent to which predators discriminate parasitized from unparasitized hosts remains unclear, particularly in generalist predators. In this study, we examine IGPc in a tritrophic system involving the omnivorous mirid predator Tupiocoris cucurbitaceus, the larval endoparasitoid Pseudapanteles dignus, and their shared herbivore host Phthorimaea absoluta. Mirid bugs are increasingly used in integrated pest management due to their efficiency and versatility as biological control agents, but their potential for intraguild predation raises concerns about their compatibility with parasitoids. Using no-choice and choice predation assays, we found that T. cucurbitaceus consumed significantly fewer parasitized larvae, particularly when parasitism was advanced, and required longer handling times for parasitized prey.Olfactometer assays revealed that females preferred volatiles from plants infested with unparasitized or recently parasitized larvae, but showed no attraction to plants with hosts parasitized for 72 hours. These findings indicate that predator foraging is shaped by bothdirect cues from prey and indirect cues mediated by herbivore-induced plant volatiles (HIPVs), and that discrimination improves as the parasitoid develops. By selectively avoiding older parasitized hosts, T. cucurbitaceus reduces antagonistic intraguild interactions, which may facilitate the stable coexistence of predators and parasitoids exploiting the same herbivore resource.