Host identity and quality drive parasitoid fitness and have implications for biocontrol

Abstract Augmentative biocontrol depends on mass‐rearing high‐quality parasitoids. Host size and quality directly influence parasitoid fitness and effectiveness, making host selection critical for pest control success. This study assessed the influence of two pyralid hosts on the fitness of Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae), an endoparasitoid of the carob moth Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae) utilizing the natural host, E. ceratoniae , and an alternative host, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). A type II functional response was observed on larval stages of both hosts, indicating similar behavioural responses to host density. No significant differences were found in attack rates, handling times, or life history and morphological traits between hosts. However, host stage significantly affected these parameters. L5 hosts produced parasitoids with the shortest development time, largest body size, longest lifespan and highest daily fecundity; traits central to effective biocontrol. Results indicate that E. kuehniella is a viable alternative host for mass‐rearing V. canescens .