Seasonal Variations of Body Weight, Lipid Reserves, Blood Volumes, and Hemocyte Population of Antheraea assama (Lepidoptera: Satumiidae)

Abstract

Performance of Antheraea assama Westwood, a multivoltine sericogenic insect, as a commercial silk producer varies during different seasons in Assam, India. This study was done to determine seasonal variation of larval period, body weight, lipid reserves, water content, blood volumes, and quantitative hemocyte compositions of the fourth (penultimate) and fifth (ultimate) instars of this species during the winter, spring, summer, and autumn. Larval period was longest (51.50 ± 0.25 d) during winter (December-February) and shortest (25.00 ± 0.29 d) during summer (May–July). Greatest larval dry body weight (19.40% and 16.77% of fresh body weight of the fourth and fifth instars, respectively) occurred during winter and autumn (October-February) whereas larvae reared during spring and summer (March-August) were characterized by lowest body weight. Similar patterns of variation of lean dry weights, lipid reserves, and total hemocyte counts were also observed. Correspondingly, spring- and summer-reared larvae showed significantly higher levels of blood volume and total water as well as cellular and gut water content in comparison with those reared during the autumn and winter seasons. This study shows that lipid reserves may enable survival of larvae during seasonal adversity.