INSECTICIDAL ACTIVITIES OF CERTAIN MINOR NUTRIENTS AGAINST THE LARVAE OF THE EGYPTIAN COTTON LEAFWORM, SPODOPTERA LITTORALIS (BOISD.) NOCTUIDAE: LEPIDOPTERA

Abstract

The insecticidal effects of four micro- nutrients, Iron (Fe+++), Copper (Cu++), Manganese (Mn++) and Zinc (Zn++) against the second and fourth instar larvae of S. Iiitomis was evaluated In laboratory tests. Larvae were fed for 48h on castor leaves Rionus communis dipped in a solution of each element at different concentrations .Copper(Cu)was the most toxic nutrient against the second and fourth instar larvae( LCso value were330 and500 ppm, respectively ). While, Manganese (Mn) came next ;( LCso value were 350 and 660 ppm, respectively).While, Iron (Fe+++) was the least one (LCE0 value were 560 andI500 ppm, respectively) .The biological activities of the treated larvae with each of the four nutrients, were affected. Copper and Manganese treatments showed as higher effects than other treatments. However, the larval and pupal duration were prolonged, the pupation and adult emergence percent were decreased, the pupal weight was decreased and pupal and adult malformation percent were noticed. Also, the fecundity and eggs hatching% were inhibited. The sex ratio of the emerged adults was more affected as compared to control .Whereas, Iron treatment had a stronger effect on some biological parameters .This led to an increase in the pupal duration and malformations and decrease in adult emergence. While the larval treatment with Zinc had the strongest effects on adult longevity and sex ratios shifting of both males and females in respect to control.