Chemical characterization and insecticidal activity of leaves and flowers of Ageratum conyzoides
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
Ageratum conyzoides (Asteraceae) is an invasive herb widely distributed in tropical and subtropical
parts of the world. The plant is widely studied due to its wide diversity in chemical
composition. In the present investigation, the evaluation of insecticidal activity of leaves and
flowers of methanol extract and its petroleum ether, chloroform and ethyl acetate fractions
were studied against second and fourth instar larvae of Spodoptera litura. The compound βcaryophyllene
was isolated from the methanol leaves extract by column chromatography. The
larval mortality of both the instars was studied after exposure to various extract and
compound at different concentrations (5, 10 and 15%) after regular interval of 24, 48 and 72 h
of treatment. It was found that methanol flowers extract exhibited the highest larval mortality
of 57.33±0.115% at 15% concentration after 72 h of treatment. Further it was observed that
the fourth instar larvae were more susceptible than second instar larvae. Therefore, parameters
like consumption index, growth index and morphological deformities were also studied for
fourth instar larvae of S. litura. It was observed that the consumption index exhibited a direct
relation with concentration and time whereas inverse relation was found with growth index.
The lowest consumption index was found in β-caryophyllene (0.030±0.034 mg mg-1day-1)
followed by methanol flowers (0.045±0.039 mg mg-1day-1) and methanol leaves
(0.057±1.417 mg mg-1day-1) extract. Various morphological deformities in larval and pupal
stages were observed. The adults emerged were reduced in size and exhibited wings
deformities. Overall, β-caryophyllene exhibited a highest insecticidal activity and has the
potential to be developed as botanical pesticide. These findings might have important
implications for environment friendly control of pests by using botanical pesticides.
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Citation
Gurdeep Kaur (2021). Chemical characterization and insecticidal activity of leaves and flowers of Ageratum conyzoides (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.