Nagwa AL-Nagar - Academia.edu (original) (raw)

Papers by Nagwa AL-Nagar

Research paper thumbnail of Antifeedant growth regulatory and bioche

Research paper thumbnail of Effect of monoterpenes, phenylpropenes and sesquiterpenes on development, fecundity and fertility of Spodoptera littoralis (Boisduval)

International Journal of Tropical Insect Science, 2021

Monoterpenes, phenylpropenes and sesquiterpenes are the major constituents of essential oils of m... more Monoterpenes, phenylpropenes and sesquiterpenes are the major constituents of essential oils of many aromatic plants and possess a wide spectrum of biological activities. In this study, the effect of eleven monoterpenes, phenylpropenes and sesquiterpenes on larval and pupal duration, pupation, pupal weight, adult emergence, fecundity and fertility of Spodoptera littoralis were evaluated. Results showed that larvae fed on the treated diet at 500, 1000 and 2000 mg/kg developed slower than those fed on untreated diet. trans - Cinnamaldehyde (500 mg/kg) was the most effective compound in increasing larval duration of 20.4 days compared to 13.5 days in control, followed by1,8-cineole and ( −)-citronellal. Also, treatment with ( −)-carvone, ( −)-citronellal, eugenol, p -cymene and α-pinene prolonged pupal duration by 1 to 3 days compared to control. On the other hand, the tested compounds significantly reduced pupation percentage and pupal weight of S. littoralis . trans -Cinnamaldehyde was more effective than a reference insect growth regulator, pyriproxyfen, in pupation percent reduction at 500 mg/kg. Furthermore, the tested compounds strongly decreased adult emergence of S. littoralis with 1,8-cineole being the most effective compound as it lowered adult emergence to 23.3, 16.7, and 13.3% at 500, 1000, and 2000 mg/kg, respectively, compared to 90.0% in control. In addition, oviposition and eclosion were significantly reduced by the tested compounds. trans -Cinnamaldehyde, ( −)-citronellal, 1,8-cineole, ( −)-carvone and ( Z,E )-nerolidol were the most effective compounds on oviposition and egg hatching reduction.

Research paper thumbnail of Antifeedant, growth regulatory and biochemical effects of terpenes and phenylpropenes on Spodoptera littoralis Boisduval

International Journal of Tropical Insect Science, 2020

Screening the biological activities of plant secondary metabolites on economic pests can lead to ... more Screening the biological activities of plant secondary metabolites on economic pests can lead to discovery new ecofriendly biopesticides. The aim of this work was to evaluate the antifeedant, growth inhibitory and toxic activities of seven monoterpenes, two phenylpropenes and two sesquiterpenes on 2nd larval instar of Spodoptera littoralis. The tested compounds induced a significant antifeedant effect at various concentrations (500, 1000 and 2000 mg/kg), particularly after 6 and 9 days of exposure. Among the tested compounds, trans-cinnamaldehyde, α-terpinene, (−)-citronellal and 1,8-cineole were the most potent antifeedants after the three exposure periods. In general the tested compounds showed remarkable antifeedant activity after 9 days of exposure as their antifeedant indices ranged between 44.0 and 80.1%. On the other hand, the tested compounds drastically inhibited the growth of S. littoralis larvae at the tested concentrations. The larval growth inhibition ranged between 21.4 and 100% with cuminaldehyde, 1,8-cineole and eugenol being the most potent growth inhibitors. Some of the tested compounds caused significantly higher antifeedant and growth inhibitory effects than a reference insecticide, pyriproxifen. In general, the tested compounds showed higher growth inhibition than antifeedant effect. The tested compound also induced S. littoralis larval morality which improved with increasing exposure time and concentration. Cuminaldehyde, 1,8-cineole and (−)-carvone showed highest toxicity with 100.0, 97.0 and 77.0% mortality, respectively, at 2000 mg/kg after 9 days of exposure. Biochemical studies revealed that trans-cinnamaldehyde (IC 50 = 0.03 mM), farnesol (IC 50 = 0.04 mM) and eugenol (IC 50 = 0.06 mM) are potent α-amylase inhibitors. These three compounds also caused significant inhibition of total proteases activity. This is the first report on antifeedant, growth inhibitory and insecticidal activities of the tested compounds on S. littoralis. Moreover, the strong bioactivity reported in this study indicated that these compounds have a potential to be used as bioinsecticides.

Research paper thumbnail of Comparative toxicity, growth inhibitory and biochemical effects of terpenes and phenylpropenes on Spodoptera littoralis (Boisd.)

Journal of Asia-Pacific Entomology, 2019

Full length article Comparative toxicity, growth inhibitory and biochemical effects of terpenes a... more Full length article Comparative toxicity, growth inhibitory and biochemical effects of terpenes and phenylpropenes on Spodoptera littoralis (Boisd.

Research paper thumbnail of Antifeedant growth regulatory and bioche

Research paper thumbnail of Effect of monoterpenes, phenylpropenes and sesquiterpenes on development, fecundity and fertility of Spodoptera littoralis (Boisduval)

International Journal of Tropical Insect Science, 2021

Monoterpenes, phenylpropenes and sesquiterpenes are the major constituents of essential oils of m... more Monoterpenes, phenylpropenes and sesquiterpenes are the major constituents of essential oils of many aromatic plants and possess a wide spectrum of biological activities. In this study, the effect of eleven monoterpenes, phenylpropenes and sesquiterpenes on larval and pupal duration, pupation, pupal weight, adult emergence, fecundity and fertility of Spodoptera littoralis were evaluated. Results showed that larvae fed on the treated diet at 500, 1000 and 2000 mg/kg developed slower than those fed on untreated diet. trans - Cinnamaldehyde (500 mg/kg) was the most effective compound in increasing larval duration of 20.4 days compared to 13.5 days in control, followed by1,8-cineole and ( −)-citronellal. Also, treatment with ( −)-carvone, ( −)-citronellal, eugenol, p -cymene and α-pinene prolonged pupal duration by 1 to 3 days compared to control. On the other hand, the tested compounds significantly reduced pupation percentage and pupal weight of S. littoralis . trans -Cinnamaldehyde was more effective than a reference insect growth regulator, pyriproxyfen, in pupation percent reduction at 500 mg/kg. Furthermore, the tested compounds strongly decreased adult emergence of S. littoralis with 1,8-cineole being the most effective compound as it lowered adult emergence to 23.3, 16.7, and 13.3% at 500, 1000, and 2000 mg/kg, respectively, compared to 90.0% in control. In addition, oviposition and eclosion were significantly reduced by the tested compounds. trans -Cinnamaldehyde, ( −)-citronellal, 1,8-cineole, ( −)-carvone and ( Z,E )-nerolidol were the most effective compounds on oviposition and egg hatching reduction.

Research paper thumbnail of Antifeedant, growth regulatory and biochemical effects of terpenes and phenylpropenes on Spodoptera littoralis Boisduval

International Journal of Tropical Insect Science, 2020

Screening the biological activities of plant secondary metabolites on economic pests can lead to ... more Screening the biological activities of plant secondary metabolites on economic pests can lead to discovery new ecofriendly biopesticides. The aim of this work was to evaluate the antifeedant, growth inhibitory and toxic activities of seven monoterpenes, two phenylpropenes and two sesquiterpenes on 2nd larval instar of Spodoptera littoralis. The tested compounds induced a significant antifeedant effect at various concentrations (500, 1000 and 2000 mg/kg), particularly after 6 and 9 days of exposure. Among the tested compounds, trans-cinnamaldehyde, α-terpinene, (−)-citronellal and 1,8-cineole were the most potent antifeedants after the three exposure periods. In general the tested compounds showed remarkable antifeedant activity after 9 days of exposure as their antifeedant indices ranged between 44.0 and 80.1%. On the other hand, the tested compounds drastically inhibited the growth of S. littoralis larvae at the tested concentrations. The larval growth inhibition ranged between 21.4 and 100% with cuminaldehyde, 1,8-cineole and eugenol being the most potent growth inhibitors. Some of the tested compounds caused significantly higher antifeedant and growth inhibitory effects than a reference insecticide, pyriproxifen. In general, the tested compounds showed higher growth inhibition than antifeedant effect. The tested compound also induced S. littoralis larval morality which improved with increasing exposure time and concentration. Cuminaldehyde, 1,8-cineole and (−)-carvone showed highest toxicity with 100.0, 97.0 and 77.0% mortality, respectively, at 2000 mg/kg after 9 days of exposure. Biochemical studies revealed that trans-cinnamaldehyde (IC 50 = 0.03 mM), farnesol (IC 50 = 0.04 mM) and eugenol (IC 50 = 0.06 mM) are potent α-amylase inhibitors. These three compounds also caused significant inhibition of total proteases activity. This is the first report on antifeedant, growth inhibitory and insecticidal activities of the tested compounds on S. littoralis. Moreover, the strong bioactivity reported in this study indicated that these compounds have a potential to be used as bioinsecticides.

Research paper thumbnail of Comparative toxicity, growth inhibitory and biochemical effects of terpenes and phenylpropenes on Spodoptera littoralis (Boisd.)

Journal of Asia-Pacific Entomology, 2019

Full length article Comparative toxicity, growth inhibitory and biochemical effects of terpenes a... more Full length article Comparative toxicity, growth inhibitory and biochemical effects of terpenes and phenylpropenes on Spodoptera littoralis (Boisd.