Conspecific egg consumption of Ephestia kuehniella neonates enhanced by Trichogramma evanescens parasitism: provoked cannibalism turns into a predation reversal in the host–parasitoid trophic system

BackgroundCannibalism directly affects the cannibal species and may indirectly influence its ecological interactions. However, its impact on trophic interactions remains underexplored, especially when cannibals consume parasitized conspecifics, potentially leading to predation reversal.ResultsThis study investigated whether parasitism of host eggs provokes cannibalism that could potentially trigger predation reversal and hinder the outcomes of biological control in an insect–insect model, particularly with a parasitoid as the secondary consumer and a lepidopteran host as the primary consumer. The density‐dependent feeding and orientation preferences of Ephestia kuehniella (Lepidoptera: Pyralidae) neonate larvae on unparasitized and/or Trichogramma evanescens (Hymenoptera: Trichogrammatidae)‐parasitized conspecific eggs were investigated in no‐choice and two‐choice experiments. The results demonstrated that E. kuehniella neonates exhibited a clear feeding and orientation preference toward parasitized conspecific eggs over healthy ones in both no‐choice and two‐choice experiments. The orientation preference was not different only in several cases, whereas the higher consumption of parasitized eggs supported a clear overall preference, indicating a predation reversal in the host–parasitoid trophic level. Neonate feeding on parasitized egg batches significantly reduced the number of emerged parasitoids. Artificially damaged conspecific eggs also were preferred by neonates indicating clear interest in damaged conspecific egg content, whereas the participation of parasitoid relevant cues in perception of parasitized eggs remains yet to be investigated.ConclusionPossible reasons underlying increased consumption of parasitized eggs are discussed. This study highlights that parasitism‐induced conspecific egg consumption, provoking cannibalism, causes a predation reversal in the host–parasitoid relationship which poses a bottleneck in the operation of biological control programs. © 2025 Society of Chemical Industry.