Biological Control Potential of Nesolynx thymus (Girault) against Uzi Fly Infesting Muga Silkworm, Antheraea assamensis Helfer

Aims: The present study was undertaken to evaluate the biological control potential of Nesolynx thymus (Girault) against the uzi fly, an important parasitoid of the muga silkworm, Antheraea assamensis Helfer. Particular emphasis was placed on the effects of host age and host density on parasitisation by Nesolynx thymus. Study Design: The study comprised a laboratory evaluation of the interaction between N. thymus and the uzi fly using uzi fly populations associated with the muga silkworm. Different host ages and host densities were evaluated to determine their influence on parasitisation and parasitoid performance. Place and Duration of Study: The study was conducted at the Department of Sericulture, College of Agriculture, Assam Agricultural University, Jorhat, Assam, from 2022 to 2023. Methodology: Uzi fly-infested muga silkworms were maintained under laboratory conditions, and the resulting uzi fly pupae were exposed to N. thymus under predetermined experimental conditions. Observations included host-age preference, percentage parasitisation, parasitoid emergence and other relevant parameters. The observations were summarised using mean values. Results: The parasitisation response of N. thymus varied among the host ages evaluated. The highest mean parasitisation (86%) was recorded in 1-day-old pupae, whereas the lowest value (14%) was observed in 5-day-old uzi fly pupae. Variation in parasitisation was also observed in response to host density, with the highest value (71%) recorded at a parasitoid-to-host ratio of 3:15. Progeny production also increased with increasing host density. Conclusion: The findings indicate that N. thymus has potential as a biological control agent against the uzi fly associated with the muga silkworm. Identifying suitable host stages and appropriate parasitoid–host combinations may assist in developing an effective biological control strategy for uzi fly management.