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 of the most commercially exploited non-mulberry silkworms in tropical India. It is generally grown i  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 pupal diapause state for five to six months (January-June). During this long period of diapause losses occur due to un-seasonal and unsynchronised emergence of male and female moths which is estimated to the tune of 25-30% leading to reduction of seed production in grainages. The losses become more prevalent when dry conditions prevail soon after pre-monsoonal showers. This can be avoided by consigning the pupae of diapause termination state to low temperature. In the present study, the specific age of diapause termination state has been worked out on the basis of the presence of haemolymph biochemical constituents like glycerol, trehalose, glycogen, quantitative total proteins and free amino acids and protein profile comparing them with non-diapausing pupae harvested during first and second crop. Among diapausing pupae, the trehalose concentration always remained at its low level during diapause and an increase in concentration was observed at the fag end of diapause when pupae attained the age of 145 to 150 days. Contrary to this, the level of glycerol and glycogen was always higher through out the diapause period and a down surge in the concentration was noticed when pupae were 145 to 150 days old. The level of protein was higher in nondiapausing generation. However, the level of protein and amino acids showed a fluctuating trend through out diapause development. The haemolymph protein profile of the diapausing pupae showed the presence of a diapause specific protein band of 16kD which remained in its full intensity till the pupae attained the age of 145-150 days, thereafter, its intensity went down and protein profile of pupae looked similar to non-diapausing pupae. Therefore, it is confirmed that the diapause termination state in Daba pupae occurs when pupae become 145-150 days old. The diapausing pupae of this age can be further exploited by working out low temperature treatment schedule to avoid losses in grainages