Egg Maturation and Daily Progeny Production in the Parasitoid, Gronotoma micromorpha (Hymenoptera: Figitidae: Eucoilinae)

An ovigeny index, which is the initial egg load divided by the potential lifetime fecundity, was developed for the parasitoid, Gronotoma micromorpha (Perkins), on the host Liriomyza trifolii (Burgess) (Diptera: Agromyzidae). The value obtained for the index was estimated to be 0.54, based on the initial egg load (mean ± SD: 41.0 ± 13.5) observed in the present study and the lifetime fecundity (75.6 ± 32.6) estimated in a previous study. Gronotoma micromorpha was previously regarded as being strictly pro-ovigenic based on daily progeny production data; however, the findings of the present study showed that this parasitoid is prosynovigenic. A 3-d cycle in daily progeny production was previously reported to occur during the lifetime of adult females (6.6 d) in this species. The present study showed that the initial egg load is nearly equal to the total number of eggs deposited in 3 d following adult emergence. Therefore, it is considered that the mature eggs stored during the pupal stage are deposited during the first 3 d after adult emergence and that egg maturation in the adult stage starts on day 1 and requires 3 d to complete in G. micromorpha. To clarify the relationship between the daily progeny production and the initial egg load, a reproductive cycle consisting of maturation, deposition, and depletion of eggs is proposed. In G. micromorpha, the reproductive cycle is considered to occur twice during the female lifetime. Furthermore, it is proposed that other prosynovigenic parasitoid species have a similar reproductive cycle.

Oviposition and Development in Gregopimpla kuwanae Viereck (Hymenoptera: Ichneumonidae), a Gregarious Ectoparasitoid Wasp Attacking the Rice Skipper Parnara guttata

Gregopimpla kuwanae is a gregarious ectoparasitoid wasp attacking mature larvae and prepupae of the rice skipper Parnara guttata (Lepidoptera: Hesperiidae), a major herbivorous pest in rice paddies. Here, the biology of G. kuwanae was investigated using Galleria mellonella as a laboratory host. Adult females accepted G. mellonella cocoons for oviposition, and larvae of G. kuwanae developed successfully to adulthood on this host. Females laid, on average, 3.5 eggs per host. Time required for oviposition was relatively long (mean = 14.2 min). Survival of parasitoid offspring decreased with the increasing number of eggs on each host. Females used 18.9% of hosts for host feeding, killing the hosts with no exception. Oviposition did not occur on hosts used for feeding purpose, indicating that the parasitoid was a nonconcurrent, destructive host feeder. Newly emerging adult females carried no eggs in the ovary; females started oogenesis only after they had destructively fed on hosts. This parasitoid thus was extremely synovigenic (ovigeny index = 0). Gregopimpla kuwanae laid typically yolk-rich, anhydropic eggs. Females carried on average 15 mature eggs with 20 immature eggs, and larger females had a greater number of eggs in the ovary. Life history characteristics of G. kuwanae were discussed.