Reproductive performance of Chouioia cunea Yang (Hym.: Eulophidae) parasitizing fall webworm, Hyphantria cunea Drury (Lep.: Arctiidae)

The fall webworm, Hyphantria cunea Drury (Lep.: Arctiidae), is an important pest of forest and cultivated plants in Guilan Province, Iran. The reproductive performance of Chouioia cunea Yang (Hym.: Eulophidae), a gregarious pupal parasitoid of H. cunea was studied at 24±1°C, 70±5% (RH), and a photoperiod of 14:10 (L:D) hours. The pupal hosts were exposed to 1, 2, 4, 8, 12, 16 newly emerged adult parasitoids. The parasitoids remained in contact with host pupae for 24 hours in Petri-dishes (10x1 cm) until the death of all parasitoids. The results showed that parasitoid density influenced offspring production, as the higher parasitoid densities resulted in the lowest mean number of offspring per female (179.06± 6.29). The sex ratio was not influenced by parasitoid density, but the age of parasitoid affected sex ratio as a higher sex ratio (0.92±0.001♀) was observed in the progeny produced by younger parents. Rate of parasitism was higher at density of 4 wasps (33.33%). The mean percent parasitism by 1, 2 and 3 day-old female parasitoids were 21, 13 and 9, respectively (P<0.05). Maximum number of offspring produced per female was obtained at host/parasitoid ratio of 15 to 4. The female parasitoids survived 1-3 days after oviposition. The searching efficiency of the parasitoid decreased from 0.18 to 0.009h-1 with increasing its density. The survival rate for C. cunea was not significantly different at all densities of male or females, but a statistical difference was observed with increasing parasitoid age. It was concluded that the performance of C. cunea was mainly affected by its density and age