Suitability of pupae of the stem borer Chilo partellus (Swinhoe) (Lep., Pyralidae) of various ages for parasitism by Pediobius furvus (Gahan) (Hym., Eulophidae)

The influence of the age of host (Chilo partellus) pupae on parasitoid Pediobius furvus fecundity, developmental period, progeny production, and sex ratio is reported. The extent of parasitism was determined from the proportions of parasitoid emergence to host adults recorded. Host age was found to be an important factor in development of immature of P. furvus with greater emergence from younger hosts, and C. partellus pupae over 5-day-old being rejected by the gravid female parasitoid. The result showed that both acceptability and suitability of C. partellus pupae drop off after 2 days, and to zero after 4 days. However, the host ages that are accepted by the parasitoid appear to be fairly wide.