DETERMINATION OF TEMPERATURE SENSITIVE DIAPAUSE TERMINATION STATE OF DABA TRIVOLTINE ECORACE OF ANTHERAEA MYLITTA DRURY

Abstract

The Daba trivoltine ecorace of tropical tasar silkworm Antheraea mylitta Drury is one ofthe most commercially exploited non-mulberry silkworms in tropical India. It is generally grown inthe latitude range of 20°N to 25°N in Eastern India, especially, in parts of West Bengal, Jharkhand,Orissa, Chhattisgarh and Andhra Pradesh. The pupae of this ecorace remain in facultative pupaldiapause state for five to six months (January-June). During this long period of diapause losses occurdue to un-seasonal and unsynchronised emergence of male and female moths which is estimated tothe tune of 25-30% leading to reduction of seed production in grainages. The losses become moreprevalent when dry conditions prevail soon after pre-monsoonal showers. This can be avoided byconsigning the pupae of diapause termination state to low temperature. In the present study, thespecific age of diapause termination state has been worked out on the basis of the presence ofhaemolymph biochemical constituents like glycerol, trehalose, glycogen, quantitative total proteinsand free amino acids and protein profile comparing them with non-diapausing pupae harvestedduring first and second crop. Among diapausing pupae, the trehalose concentration always remainedat its low level during diapause and an increase in concentration was observed at the fag end ofdiapause when pupae attained the age of 145 to 150 days. Contrary to this, the level of glycerol andglycogen was always higher through out the diapause period and a down surge in the concentrationwas noticed when pupae were 145 to 150 days old. The level of protein was higher in nondiapausinggeneration. However, the level of protein and amino acids showed a fluctuating trendthrough out diapause development. The haemolymph protein profile of the diapausing pupae showedthe presence of a diapause specific protein band of 16kD which remained in its full intensity till thepupae attained the age of 145-150 days, thereafter, its intensity went down and protein profile ofdiapausing pupae looked similar to non-diapausing pupae. Therefore, it is confirmed that the diapausetermination state in Daba pupae occurs when pupae become 145-150 days old. The diapausingpupae of this age can be further exploited by working out low temperature treatment schedule toavoid losses in grainages