SUITABILITY OF AGE OFEXORISTA BOMBYCIS (LOUIS) FOR THE BREEDING OF THE PARASITOID, NESOLKVX THYMUS GIRAULT (HYMENOPTERA: EULOPHIDAE)

摘要

Detailed investigations were undertaken to understand the influence of host age on the developmental biology ofNesolynx thymus Girault, an ecto-pupal gregarious parasitoid of the tachinid (uzi) fty,Exorista bombycis (Louis), an endo-larval parasitoidof the silkworm, Bombyx mori L., using 3 -11 day-old pupae of E. bombycis. In the first generation, the parasitoid developmental duration significantly reduced when the host pupae close to adult eclosion (10 -11 day-old) were parasitized. Highly significant decrease in female and total parasitoid progeny produced per host pupa, sex ratio, and parasitoid female longevity was observed when the host pupae above the age of 6 -7 days were provided. By contrast, the male progeny increased significantly (P< 0.01) when the host pupae older than 6 -7 days were parasitized by AT. thymus. When the first generation parasitoid adults (emerging from 3-11 day old host pupae) parasitized 3 day-old host pupae, only those emerged from 9-11 day-old pupae showed significantly reduced developmental duration and sex ratio. However, such females produced significantly higher male progeny. Correlation analysis of the data for first generation indicated significant negative relationship between host age and number of pupae parasitized, female and total progeny, sex ratio, and female longevity. The results clearly demonstrate that E. bombycis pupae up to 6-7 days-old are ideal for enhancing the female progeny production with improved fitness characteristics in the mass multiplication of M thymus.