Tungsten oxide, magnetic and Cu-doped magnetic nanoparticles mixtures with cyromazine as promising eco-friendly strategies to control of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)

Abstract

Abstract Excessive application of pesticides leads to contamination of the environment, which entails the necessity to seek solutions that employ substances which do not pose ecological hazards. So, the present study was conducted to explore the different effects of tungsten oxide (WRT), magnetic nanoparticles (MNPs), Cu-doped magnetic nanoparticles (MNP-Cu), the insecticide, cyromazine, and their binary mixtures against Spodoptera littoralis. The nanomaterials individually didn’t show any toxicity against S. littoralis stages. Cyromazine recorded the highest toxicity with LC50 values of 58.7, 45.6, and 70.5 mgL− 1 against eggs, 2nd, and 4th larvae, respectively. Nanoparticles showed an antagonistic effect which increased directly with concentrations. Cyromazine (100 mgL− 1) + MNP-Cu (500 mgL− 1) was the most repellent mixture for the 2nd and 4th larvae with feeding deterrence percent, 41.42% and 57.60%, respectively. Larval and pupal durations increased with increasing cyromazine and nanomaterial concentrations. Except for the cyromazine (25 mgL− 1) + WRT (500 mgL− 1) mixture, which recorded 27.3% adult emergence, no adult emergence was recorded by the 500 mgL− 1 nanomaterial mixtures. Some malformations were also recorded for S. littoralis stages after being treated with tested materials. Cyromazine/MNP-Cu mixtures gave the highest significantly increased in the enzyme activity of glutathione S-transferase and α-esterase compared to the control. Regarding the results obtained by the Q-PCR, the insect immune response for the treatments indicated a high immune response in all the treated insects compared to the control. In conclusion, the nanomaterial-cyromazine mixtures may be recommended as promising alternatives for S. littoralis control.