Vol. 11, Issue 5 (2022)

Author(s):
Kumari Pragya and SB Das

Abstract:
Various morphological, biophysical and biochemical characters of host plant affects the growth and development of insects. In lepidopterous insects, the larval growth is completed through various numbers of moultings, resulting into various instars. These successive instars exhibits progressive growth in the size of body structures viz. head capsule width (HCW), body length (BL) and body width (BW) as defined by Dyar’s law (1890) and Przibram’s and Megusar’s rule (1912). The present study is mainly focused on the applicability of Dyar’s law and Przibram’s and Megusar’s rule on the progressive development of larval HCW, BW and BL of S. litura fed on highly and least susceptible genotypes (JS 22-05 and JS 21-71, respectively) of soybean to check the effect of susceptibility of genotypes on the progressive development of S. litura larvae. The results of present study revealed that the head capsule growth shown by different instars of S. litura larvae reared on highly and least susceptible genotype followed the geometrical progression as proposed by Dyar’s law (1890) whereas, successive increase in body length and body width did not follow the geometrical progression as proposed by Przibram’s and Megusar’s rule and there was no effect of susceptibility of genotypes on the progressive increase of the HCW of S. litura larvae.