Toxic and Antifeeding Activities of Certain Plant Extracts and Their Effects on Biological and Biochemical Aspects of the Cotton Leafworm Spodoptera Littoralis (Boisd.

Abstract

The present work aimed to study the toxic and antifeeding activities of certain plant extracts against Spodoptera littoralis (Boisd.) The extracts of lantana and lemongrass leaves were applied at 5 & 10% concentrations, against 2 nd and 4 th instars larvae of S. littoralis under laboratory conditions 27 ± 2 °C and 55 -65% relative humidity. Results showed that the lemongrass extract in water at 10% conc. on the 2 nd larval instar and lantana extract in water at 10% conc. on 4 th larval instar were the highest in efficacy as antifeedants. Regarding, conversion of ingested and digested food (ECI) & (ECD) lantana extract in water 10% had the least effect. The highest mortality percentage was attained from the lemongrass extract in acetone 10% and lantana extract in water 5% treatments against both the 2 nd and 4 th larval instars, respectively. Data showed that all the plant extracts caused significant reductions in respect of larval and pupal durations, pupal weight and % of adult emergence compared with the untreated check. The plant extracts had a clear effect on the carbohydrates hydrolysis enzymes as amylase and trehalse.