Korbi is a sal fed ecorace of tropical tasar silk insect Antheraea paphia Linn. The insect is bivoltine, wild, eurythermic, polyphagous insect available naturally in Korba area of Chhattisgarh, India, especially in the Karela Hills up to a height of 992m AMSL. This race is endemic to Korba hills groups because all the ecological requirements of the race are at optimum level for the growth and survival. The nomenclature of the ecorace Korbi of the present investigation is also associated with the tribal community ‘Korwas” inhabiting in the area. Under the present investigation, 14 traits of male and female cocoons for 11 interim measures were analyzed and their significance was evaluated. In the present investigation, silk structure and variations in  silk associated quantitative traits of natural population of males and females of ecorace Korbi collected from Korba forest were studied. The male and female populations of ecorace Korbi of A. paphia presented a different structure and functional relation between the associates. The length of male cocoons adduced significant association with the breadth of cocoons (r=0.859**., P< 0.01., Df=13), length- breadth ratio of cocoons (r=0.587**., P<0.01., Df=13) and volume of cocoons (r=0.945**., P< 0.01., Df=13).The volume of cocoons in male population conferred significant increase with the increase in breadth of cocoons (r=0.963**.,P< 0.01., Df=13). The predictor variable ‘length-breadth ratio’ of male cocoons presented a control of 26.01 percent over criterion variable ‘horizontal circumference of male cocoons’ (r=0.510**., P<0.01., Df=13). The ‘cocoon weight’ in male surmised a positive and significant association with the ‘shell weight’ (r=0.763**., P < 0.01., Df=13) and ‘pupa weight’ (r=0.963**., P<0.01.,Df=13). Likewise, the increase in ‘shell weight’ of male population deduced a significant increase in ‘pupa weight’ (r=0.491**., P<0.05.,Df=13) and ‘shell percent’ (r=0.777**., P<0.01., Df=13).

                             The ‘length of peduncle’ in female cocoons exhibited significant association with the ‘thickness of peduncle’ (r=0.478*., P<0.05., Df=13) and ‘volume of cocoons’ (r=-0.480., P<0.05., Df=13).The fairly god thickness of peduncle in female cocoons acted as an indicator for significantly higher ‘length of cocoons’, ‘breadth of cocoons’, ‘horizontal circumference of cocoons’, ‘cocoon weight’, ‘shell weight’, ‘pupa weight’ and ‘volume of the cocoons’. The ‘length of cocoons’ in female population adjudicated significant positive association with the ‘breadth’, ‘length-breadth ratio’, longitudinal circumference, ‘horizontal circumference’ and ‘volume of the cocoons’. The increase in breadth of cocoons elucidated significant increase in’ longitudinal circumference’, ‘horizontal circumference’, ‘cocoon weight’  and volume of the cocoons. The increase in ‘length-breadth’ ratio of female cocoons conferred positive and significant influence on ‘longitudinal-horizontal circumference ratio’ of cocoons (r=0.585**., P<0.01., Df=13).The ‘longitudinal circumference’ of cocoons in female population showed mutual interdependence for increase in ‘horizontal circumference of cocoons’ (r=0.837**.,P<0.01., Df=13) and ‘volume of cocoons’ (r=0.907**.,P<0.01., Df=13). The increase in’ horizontal circumference’ of cocoons communicated positive increase in the volume of cocoons (r=0.930**., P<0.01., Df=13). The relation between ‘cocoon weight’ and ‘shell weight’ and ‘cocoon weight’ with ‘pupa weight’ were significant at 1 percent level of significance and that of ‘cocoon weight’ with ‘volume of cocoon’ was significant at 5 percent level of significance.

The Fisher’s ratios of variance between the sexes were significant for the ‘length of cocoons’, ‘breadth of cocoons’, longitudinal circumference of cocoons, ‘horizontal circumference of cocoons’, ‘longitudinal-horizontal circumference ratio’ of cocoons, ‘cocoon weight’, ‘shell weight’, ‘pupa weight’, ‘shell percent’ and ‘volume of the cocoons’ at 1 percent level of significance. The significance was further confirmed by DMRT at 5 percent level of significance. Chi square (X2) for the different traits between the sexes conferred no difference between the observed and expected frequencies and  thus, failed to reject the null hypothesis. Test of significance (t) between the sexes adduced significant variation in the ‘length of peduncle’, ‘thickness of peduncle’, ‘diameter of peduncle’, ‘length of cocoon’, ‘breadth of cocoon’, ‘longitudinal circumference of cocoons’, ‘horizontal circumference of cocoons’, ‘longitudinal-horizontal circumference ratio’ and ‘volume of cocoons’ ( P<0.01.,Df=13). The correlation between the sexes for the ‘diameter of peduncle’ and ‘horizontal circumference’ of cocoons revealed significant association at 5 percent level of significance. The regression function between both the sexes for ‘diameter of peduncle’ remained as Y=5.98352-0.414967X, where X is the diameter of peduncle of male population and Y is ‘diameter of peduncle’ of female population. The regression function between the sexes for horizontal circumference of cocoons remained as Y=19.23771-1.037262X.

Sal fed ecorace Korbi, Antheraea paphia, quantitative traits, structural and functional relations, regression function, cocoon associates