Background Botanical extracts are emerging as sustainable, multi-mechanistic alternatives to synthetic fumigants for controlling stored grain pests like the Angoumois grain moth (Sitotroga cerealella). This study investigated six locally available plants—Dysphania ambrosioides (Mexican tea), Calotropis procera (calotrope), Moringa oleifera (moringa), Nerium oleander (oleander), Lawsonia inermis (henna), and Acacia nilotica (acacia)—to evaluate their phytochemical composition, antioxidant potential, pesticidal efficacy, grain protection capacity, and impacts on insect physiology. Results Phytochemical screening revealed strong variation among extracts, with A. nilotica having the highest phenolic content. Quantitative assays confirmed that phenolic levels were closely linked to antioxidant capacity, as reflected by the lowest DPPH-IC50 value (59.43 µg mL− 1). Bioassays demonstrated dose-dependent insecticidal effects. Adult mortality was particularly rapid with D. ambrosioides and N. oleander, with LT50 ≈ 0.38–0.39 days at 10 mg g-1, whereas emergence reduction exceeded 90% at the highest concentrations across most extracts. Dysphania ambrosioides consistently demonstrated the highest efficacy, with emergence suppression of up to 98.26%, minimal grain weight loss (0.69%), and the lowest percentage of insect-damaged grains (3.00%). Acacia nilotica and C. procera also produced strong protective effects at elevated concentrations, whereas L. inermis and M. oleifera were generally less effective. Biochemical assays revealed that all the extracts significantly reduced aspartate aminotransferase (AST) levels, whereas the C. procera and L. inermis extracts increased superoxide dismutase (SOD) and reduced glutathione (GSH) levels, indicating diverse mechanistic responses. Correlation analysis revealed that phenols were negatively associated with AST and alkaline phosphatase, flavonoids were negatively correlated with SOD, and carbohydrates showed strong negative associations with alanine aminotransferase and SOD, as well as positive associations with grain damage indices. Conclusion This study demonstrated that plant extracts, particularly D. ambrosioides, N. oleander, and A. nilotica, exhibit strong bioefficacy against S. cerealella, substantially reducing moth development and grain damage. M. oleifera and L. inermis provided complementary but weaker protection. The observed phytochemistry–bioefficacy correlations suggest that phenolics underpin both antioxidant strength and enzyme suppression, whereas carbohydrate-rich extracts contribute to weaker performance. Collectively, these findings highlight the potential of local botanicals as scalable, safer alternatives to chemical fumigants, supporting sustainable postharvest pest management strategies. Graphical Abstract

Phytochemistry and insecticidal activity of six local plant extracts against Sitotroga Cerealella (Oliv.) (Lepidoptera: Gelechiidae) in stored wheat

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2025年12月29日

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Ahmed M. A. Salman,
Nessma M. Abdeen,
Fatma S. Ahmed

摘要

Background

Botanical extracts are emerging as sustainable, multi-mechanistic alternatives to synthetic fumigants for controlling stored grain pests like the Angoumois grain moth (Sitotroga cerealella). This study investigated six locally available plants—Dysphania ambrosioides (Mexican tea), Calotropis procera (calotrope), Moringa oleifera (moringa), Nerium oleander (oleander), Lawsonia inermis (henna), and Acacia nilotica (acacia)—to evaluate their phytochemical composition, antioxidant potential, pesticidal efficacy, grain protection capacity, and impacts on insect physiology.

Results

Phytochemical screening revealed strong variation among extracts, with A. nilotica having the highest phenolic content. Quantitative assays confirmed that phenolic levels were closely linked to antioxidant capacity, as reflected by the lowest DPPH-IC₅₀ value (59.43 µg mL^− 1).

Bioassays demonstrated dose-dependent insecticidal effects. Adult mortality was particularly rapid with D. ambrosioides and N. oleander, with LT50 ≈ 0.38–0.39 days at 10 mg g-1, whereas emergence reduction exceeded 90% at the highest concentrations across most extracts. Dysphania ambrosioides consistently demonstrated the highest efficacy, with emergence suppression of up to 98.26%, minimal grain weight loss (0.69%), and the lowest percentage of insect-damaged grains (3.00%). Acacia nilotica and C. procera also produced strong protective effects at elevated concentrations, whereas L. inermis and M. oleifera were generally less effective. Biochemical assays revealed that all the extracts significantly reduced aspartate aminotransferase (AST) levels, whereas the C. procera and L. inermis extracts increased superoxide dismutase (SOD) and reduced glutathione (GSH) levels, indicating diverse mechanistic responses.

Correlation analysis revealed that phenols were negatively associated with AST and alkaline phosphatase, flavonoids were negatively correlated with SOD, and carbohydrates showed strong negative associations with alanine aminotransferase and SOD, as well as positive associations with grain damage indices.

Conclusion

This study demonstrated that plant extracts, particularly D. ambrosioides, N. oleander, and A. nilotica, exhibit strong bioefficacy against S. cerealella, substantially reducing moth development and grain damage. M. oleifera and L. inermis provided complementary but weaker protection. The observed phytochemistry–bioefficacy correlations suggest that phenolics underpin both antioxidant strength and enzyme suppression, whereas carbohydrate-rich extracts contribute to weaker performance. Collectively, these findings highlight the potential of local botanicals as scalable, safer alternatives to chemical fumigants, supporting sustainable postharvest pest management strategies.

Graphical Abstract