Larval Development of Spodoptera litura Fabricius in Relation to Castor Varieties and Biochemical Constituents

Abstract

The effect of biotic conditions, represented by different castor varieties, on the development and fecundity of Spodoptera litura was studied. Higher larval mortality occurred on GCH-4 and GCH-5 within two days, whereas lower mortality of first-instar larvae was observed on castor varieties VI-9 and GAUCH-1. None of the larvae survived or completed development on DCS-9, VP-1, Geeta, CO-1, JI-35, GCH-4, and GCH-5, whereas 40–56% larval survival was recorded on VI-9, GAUCH-1, 48-1, SKI-73, and SH-72. The larval period of S. litura was longer on SKI-73 and SH-72 than on GAUCH-1, VI-9, and 48-1, while the pupal period was longer on SH-72 than on VI-9 and GAUCH-1. Fecundity was higher on VI-9 than on SH-72, SKI-73, 48-1, and GAUCH-1. Biochemical analysis revealed that higher contents of total soluble sugars and amino acids in the leaves of VI-9 and GAUCH-1 enhanced the feeding activity of S. litura larvae compared with GCH-4 and GCH-5. In contrast, higher levels of peroxidase and polyphenol oxidase in the leaves of GCH-4 and GCH-5 made these varieties less favourable for S. litura compared with VI-9 and GAUCH-1.