Background Sucking insects are major threat to agricultural and horticultural crops. Indiscriminate application of chemical insecticides for the control of pests leads to the development of resistance, harmful to non-target organisms, consumers’ health, the environment, etc. Therefore, botanical insecticides are alternate to synthetic pesticides for the control of sucking pests. In the present investigation, chemical constituents, metabolic profile, and insecticidal activities of Rosmarinus officinalis L. (Lamiaceae) ethanolic aqueous extract (EAE), fractions and compounds were screened against Aphis craccivora Koch (Hemiptera: Aphididae) and Planococcus lilacinus Cockerell (Hemiptera: Pseudococcidae). Results Gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) analysis showed that linolenic acid (24.97%), 1,8-cineole (14.26%), myrcene (10.67%), hexadecenoic acid (9.91%), and camphene (7.12%) were the major constituents in the n-hexane fraction. UHPLC–ESI-QTOF-IMS analysis of ethanolic aqueous extract (EAE) showed the presence of palmitoleic acid, 4-ethoxy ethyl benzoate, 7-methylrosmanol, and diosmin as major metabolites. Among extract and fractions, EAE was found more effective to A. craccivora (lethal dose to kill 50% of test insect i. e., LD50 = 1.84 µL/nymph) after 96 h followed by n-hexane fraction (LD50 = 2.22 µL/insect). In P. lilacinus, n-hexane fraction displayed highest toxicity (LD50 = 1.46 µL/crawler) followed by ethyl acetate and n-butanol fraction (LD50 = 2.01–2.29 µL/crawler). All combinations of the EAE and fractions exhibited synergetic action. Amongst compounds, linolenic acid was found superior to A. craccivora (LD50 = 0.59 µL/nymph) and P. lilacinus (LD50 = 0.99 µL/crawler). EAE and its fractions also showed significant reproductive inhibition and deterrence to target pests. Further, EAE significantly inhibited in vivo enzyme acetylcholinesterase (AChE), glutathione-S-transferase (GST), and mixed function oxidase (MFO) in A. craccivora after 24 and 48 h. In P. lilacinus, only GST showed inhibition but AChE and carboxylesterase (CES 1) were induced after 24 h. SEM study revealed notable aberrations in the structure of the peritoneum, setae, and thoracic legs of A. craccivora after ingestion of EAE. Under greenhouse conditions, the higher dose of R. officinalis EAE (20 g/L) reported higher reduction of A. craccivora on leaf (82.28 to 89.36%) and twigs (70.68 to 85.72%) of cowpea after 3, 5 and 7 days of second spray. Conclusion Based on our greenhouse study results, EAE of R. officinalis may be recommended for the control of A. craccivora in crop plants. Graphical Abstract

Metabolic profiling and insecticidal activities of Rosmarinus officinalis L. for the management of Aphis craccivora Koch and Planococcus lilacinus Cockerell

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2025年4月10日

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Urvashi Kashyap,
S. G. Eswara Reddy

摘要

Background

Sucking insects are major threat to agricultural and horticultural crops. Indiscriminate application of chemical insecticides for the control of pests leads to the development of resistance, harmful to non-target organisms, consumers’ health, the environment, etc. Therefore, botanical insecticides are alternate to synthetic pesticides for the control of sucking pests. In the present investigation, chemical constituents, metabolic profile, and insecticidal activities of Rosmarinus officinalis L. (Lamiaceae) ethanolic aqueous extract (EAE), fractions and compounds were screened against Aphis craccivora Koch (Hemiptera: Aphididae) and Planococcus lilacinus Cockerell (Hemiptera: Pseudococcidae).

Results

Gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) analysis showed that linolenic acid (24.97%), 1,8-cineole (14.26%), myrcene (10.67%), hexadecenoic acid (9.91%), and camphene (7.12%) were the major constituents in the n-hexane fraction. UHPLC–ESI-QTOF-IMS analysis of ethanolic aqueous extract (EAE) showed the presence of palmitoleic acid, 4-ethoxy ethyl benzoate, 7-methylrosmanol, and diosmin as major metabolites. Among extract and fractions, EAE was found more effective to A. craccivora (lethal dose to kill 50% of test insect i. e., LD₅₀ = 1.84 µL/nymph) after 96 h followed by n-hexane fraction (LD₅₀ = 2.22 µL/insect). In P. lilacinus, n-hexane fraction displayed highest toxicity (LD₅₀ = 1.46 µL/crawler) followed by ethyl acetate and n-butanol fraction (LD₅₀ = 2.01–2.29 µL/crawler). All combinations of the EAE and fractions exhibited synergetic action. Amongst compounds, linolenic acid was found superior to A. craccivora (LD₅₀ = 0.59 µL/nymph) and P. lilacinus (LD₅₀ = 0.99 µL/crawler). EAE and its fractions also showed significant reproductive inhibition and deterrence to target pests. Further, EAE significantly inhibited in vivo enzyme acetylcholinesterase (AChE), glutathione-S-transferase (GST), and mixed function oxidase (MFO) in A. craccivora after 24 and 48 h. In P. lilacinus, only GST showed inhibition but AChE and carboxylesterase (CES 1) were induced after 24 h. SEM study revealed notable aberrations in the structure of the peritoneum, setae, and thoracic legs of A. craccivora after ingestion of EAE. Under greenhouse conditions, the higher dose of R. officinalis EAE (20 g/L) reported higher reduction of A. craccivora on leaf (82.28 to 89.36%) and twigs (70.68 to 85.72%) of cowpea after 3, 5 and 7 days of second spray.

Conclusion

Based on our greenhouse study results, EAE of R. officinalis may be recommended for the control of A. craccivora in crop plants.

Graphical Abstract