Physical- and phytochemical analyses of some citrus peel extracts, and their activity against the cotton leafworm, spodoptera littoralis (boisd.)

peels of fresh navel orange (citrus sinensis) and lemon (citrus limon) fruits (Rutaceae) were extracted by absolute methanol (MeOH) and Hexane (Hex) as solvents differing in their polarities. The purpose was to detect some chemical and physicochemical characters of their crude extracts, and evaluate their bioactivity against 4th larval instar of the cotton leafworm, Spodoptera littoralis using different methods of treatments. MeOH proved to be significantly (P 4 for Hex and MeOH extracts, respectively. Toxicity of citrus peel crude extracts against S. littoralis larvae showed that treatment by contact method was more efficient than ingestion, and Hex extracts were more toxic than MeOH extracts in both treatments. Citrus peel extracts showed relatively strong contact action, moderate repellency, weak ingestion and antifeedant activity against the 4th instar larvae. It is suggested that Hex could extracts toxic substances more than MeOH, out of the studied phytochemicals. Citrus peel waste is promising as a natural biopesticide, and its activity is determined by the solvent used for extraction, citrus species and method of treatment.