Evaluating the persistence and insecticidal effects of emulsifiable concentrate containing Cananga odorata essential oil on survival and enzymatic activity of Spodoptera littoralis

Abstract The essential oil of Cananga odorata was prepared as an emulsifiable concentrate formulation and examined for its insecticidal activity against Spodoptera littoralis larvae. The effectiveness of C. odorata oil in both pure and EC formulations was investigated in terms of enzymatic activity and survival. In addition, their persistence effect was studied in semi-field conditions. Benzyl benzoate (18.86%), benzyl acetate (9.18%), β-Maaliene (15.53%), alloaromadendrene (6.41%), cis-Thujopsene (6.16%), cedrene (5.35%), and benzyl alcohol (5.98%) were the most abundant compounds found in C. odorata oil by gas chromatography-mass spectrometry analysis. The EC formulation exhibited the highest toxicity and produced LC values of 0.47, 1.02, and 3.78% for LC 40 , LC 50 , and LC 90 , respectively, compared to 1.05, 1.70, and 4.96%, respectively, resulted from pure oil after 72 h of exposure. Following EC application, the mean survival time was only 3.60 ± 0.57 days, compared to pure oil treatment (7.70 ± 1.11 days) and control (14.0 ± 0.0 days). The LC 40 of EC formulation induced a more potent inhibitory effect for the detoxification enzyme carboxylesterases (CarE; α- and β-esterase) and the oxidative stress enzyme superoxide dismutase (SOD). Under semi-field conditions, the cumulative mortality of S. littoralis larvae increased by increasing the exposure time to LC 90 of both formulations. The EC formulation had the highest mortality rates for the total exposure period (7 days). According to these results, C. odorata EC formulation demonstrated enhanced toxicity and persistence effects, and it can be utilized as a green bio-insecticide for the management of S. littoralis larvae.