抄録
The braconid wasp, Apanteles baoris, is a gregarious larval parasitoid of the rice-plant skipper, Parnara guttata guttata (Lepidoptera: Hesperiidae), which is an important insect pest of the rice plant in Japan. To investigate the developmental relationship of these species, host larvae experimentally parasitized by A. baoris at the 1st to 5th instars were reared at 25°C under 16L8D. A. baoris was able to parasitize all instars of larval P. g. guttata, and egression of A. baoris occurred in the late final instar of the host. The rate of hosts from which A. baoris egressed was 27–72% and there was no significant difference among the rates irrespective of the host instar. The number of A. baoris adults emerging per host, or “parasitoid brood size”, ranged 4–112 (mean, 51). The mean periods from oviposition to egression of A. baoris were 15–31 days, longer than the corresponding developmental periods of unparasitized hosts. Most parasitized hosts made a 5th larval molt and became 6th-instar larvae, while all unparasitized host larvae pupated after the 5th instar. The mean maximum weight of parasitized hosts was significantly less than that of unparasitized hosts when they oviposited at 1st–3rd instars. The maximum weight of parasitized hosts was significantly and positively correlated with parasitoid brood size, and the parasitoid brood size and weight of A. baoris adults emerging from hosts were negatively correlated in both sexes.
