Abstract:
Coccidohystrix insolita, a common plant pest, poses economic threats to agriculture and
horticulture, often requiring the use of synthetic insecticides for control. To address
environmental and health concerns, this research explored natural alternatives in the
form of methanolic leaf extracts from five plants: Vitex negundo, Cymbopogon citratus,
Cassia auriculata, Justicia adhatoda, and Ricinus communis. The mortality test was
conducted under laboratory conditions, using two concentrations (1% and 3%) over a
period of 3 days, with four replications. The results were, analyzed using Minitab
Statistical Software Package and, revealed that Cymbopogon citratus exhibited the
highest insecticidal activity, with a rating of 85.00±5.65 after 3 days at a 3%
concentration, while Cassia auriculata displayed the lowest activity, scoring
10.00±4.74 after 3 days at a 1% concentration among the plant extracts. The crude
extract of Cymbopogon citratus was fractionated through column chromatography
(length =110 cm, diameter = 8.0 cm), using silica gel (400 g, Merck Kieselgel 60,230
430 mesh ASTM). A solvent system with increasing polarity was employed, starting
with hexane and progressing through ethyl acetate, ultimately reaching methanol with
distilled water via ethyl acetate with methanol. This resulted in 9 distinct fractions,
further isolated through thin-layer chromatography. Stock solutions of each fraction
were prepared at a 1000 ppm concentration in methanol for insecticidal activity.
Contact bioassay was conducted, and fraction F4 displayed the highest insecticidal
activity against Coccidohystrix insolita.
