Functional analysis of Caspase-1 in Cotesia chilonis via pupal microinjection and larval nanomaterial immersion-mediated RNA interference.

Cotesia chilonis, a dominant endoparasitoid of the striped stem borer, Chilo suppressalis, plays a crucial role in regulating the population of C. suppressalis in the field. RNA interference (RNAi) in C. chilonis is challenging due to the unique biological traits of endoparasitoids. In this study, dsRNA was delivered to C. chilonis by microinjection of pupae within cocoons (delivery outside the host) and nanomaterial-mediated immersion, which delivered dsRNA to larvae inside the host. Both systems were effective in silencing the target gene, Cccaspase-1, with microinjection achieving 41.34% RNAi efficiency in 4-d-old pupae, and nanomaterial immersion exhibiting a slightly higher efficacy (45.63%); furthermore, the results indicated a crucial role for Cccaspase-1 in the growth and development of C. chilonis. Delivery of dsRNA by microinjection offers a high level of precision and is suitable for small-scale genetic screening, whereas nanomaterial immersion enables high-throughput delivery of dsRNA and can be used to monitor silencing effects throughout the development of C. chilonis. This study provides key insights for optimizing RNAi techniques in endoparasitoid wasps.