Studies on the High Temperature Induced Stress on the Biochemical Profile and Fecundity of Daba and Laria Ecoraces of Tropical Tasar Silkworm Antheraea mylitta Drury (Lepidoptera: Saturniidae)

Abstract

Tropical tasar silkworm Antheraea mylitta Drury experiences extreme temperature stress conditions during its life cycle particularly during diapauses and first crop. The present study witnessed the impact of high temperature on some biochemical profiles and egg production (fecundity) of semi-domesticated Daba and Shorea robusta (Sal) based wild ecorace Laria during seed cocoon (pupa) preservation. Cocoons of Daba and Laria were treated with high temperature at <TEX>$40^{\circ}C$</TEX> for 10 days in a BOD incubator. The protein profile and carbohydrate content in the hemolymph and fat body and total haemocyte count (THC) in the hemolymph of pupa were investigated. Further, the fecundity and fertility of egg was assessed. Significant increase in the protein concentration was observed in the hemolymph with reduction in the fat body (p<0.05). The difference in protein concentration was highly significant between the semidomesticated Daba and wild ecorace Laria (p<0.05). High pupal mortality (20%) and reduced fecundity (10-15%) in Daba was noticed compared to wild Laria. Also an increased THC (>28000) was recorded in Laria. The study infers the potentials of wild ecoraces in sustaining the extreme temperature conditions and need of adopting suitable package of practices for the preservation of diapause seed cocoons during extreme summer conditions. There is possibility to introgression thermal stress resistant traits in the semi-domesticated races of tasar silkworm by resorting to conventional breeding plans with wild races and keeping the thermal stress induced response as markers.