Complex interactions in host-selection: decoding behaviour in Sclerodermus cereicollis for effective pest control

Sclerodermus cereicollis Kieffer (Hymenoptera, Bethylidae) is a potential biological control agent for wood-boring beetles. Initially recorded in Italy in association to the exotic Psacothea hilaris hilaris (Pascoe) (Coleoptera, Cerambycidae), this native parasitoid could also be used against other invasive longhorn beetles. To enhance its efficacy in biocontrol programs, experi mental trials were conducted to investigate S. cereicollis bioethology, focusing on developmental cycle, reproductive behaviour, and the feasibility of mass rearing this species on factitious hosts. Laboratory trials enhanced knowledge of quasi-social reproduction observed in Sclerodermus, where several female parasitoids paralyse a host and take care for their communally-produced offspring t ogether. Kinship among female foundresses and host quality both influence host selec tion. Controlled choice tests, progressively increasingly complexity in terms of host-parasitoid interactions (e.g. parasitoid-host ratios, offspring o rigin a nd k inship), s howed t hat foundress kinship, host quality and availability all influence host s election. Further, when multiple females emerge from the same brood, they tend to segregate, possible in order to parasitise as many hosts as possible. These findings improve our understanding of the behavioural-ecological inter actions among S. cereicollis and have implications for optimizing its application as a biological control agent.