Evaluation of the insecticidal and antifeedant activities of some seaweed extracts against the Egyptian cotton leaf worm, Spodoptera littoralis, and the lesser grain borer Rhyzopertha dominica

Abstract

Environmental safety and agricultural sustainability are important for survival on the Earth. Spedoptera littoralis and Rhyzopertha dominica are among the most destructive pests for economic crops in Egypt. Indiscriminate use of chemical pesticides called for safe alternatives. seaweeds are among these alternatives Hence, it is imperative to evaluate the efficacy of (Sargassum acinarium, Turbinaria turbinata, Petrocladia capillacea, and Cystoseira myrica ) extracts against S. littorlais third and fifth instar larvae and R. dominica adults. The seaweed extracts-insect contact method was used. Also the antifeediant activities of the tested sea weeds were recorded. All tested seaweeds exhibited insecticidal and antifeediant activities with S.littoralis third instar larvae being more susceptible. T. turbinata and P. capillacea exhibited the highest insecticidal and antifeddiant effects, respectively. C. myrica showed the lowest insecticidal and antifeediant activities at all. There was a direct relationship between the percent mortalities and seaweed concentrations. Sea weeds gas chromatogra¬phy-mass spectrometry analyses revealed different bioactive compounds, which might be responsible for their insecticidal properties.. finally the tested seaweeds can be used as ecofriendly and safe biopes¬ticides for control of S. littoralis and R. dominica and we recommend them to be involved in integrated pest management program.